AU544112B2 - Logging a borehole while drilling - Google Patents

Description

j~j,

Naime MC

a U..LLA TENTY DO O'UAFIS 4§ DMktararitin

6112 0/8o COMMONWEALTH OF AUSTRALIA Patenu Aci 1952-1966

CONVENTION APPLICATION FOR A PATENT *INSTDI ofTON aplicauyt() Serge A. Scherbatskoy, a citizen of the U..S.A. pplicatio-1 was :It;dat~;%and full in'.s-) ide-sLandes in. denl' undannieldung geb ,clui:wirde, a'sDatumi n;idI derldie Ide, ,1Naende, MOf P. 0. Box 1936, 1100 Everrnan Road an e dc

4,550 Fort Worth, Texas 76101, U.S.A. Itine(s) of actual 6r(s). Name cdesider en Erfiadtr(s).

hereby apply for the grant of a Patent for an invention entitled BOREHOLE MEASUREMENT WHILE IDRILLING entinn. SYSTEMS AND METHODS .ssS)s of actual Which. is described in the accompanying comrplete specification. This application is a Convention or(sq). ,application, and is 'based on the'following application or applicE&ions for a patent or parents or s casrselbefl. similar protection made in the following country or countries. in,ncr in Nyilc :ant(s) derive(s) ross actua

L.S.A o Augmat 19 No. the assikneels) of :-tjon(s) was] -11inelfvntor(5i). ~date anrd iand Ic durch c~lchmn ind dc,rldic o 19 No I(Il bcf'ugt sinid den dcr Erindung cm -cigentlichen.

No.. DerX Awncider 'it cwollmtaechsigtc =r eigentlichen cr(.s),

Mx/~ address for ser-vice is care of R. K. I4ADDE.RN and ASSOCIATES, Potent Attorneys. raph 4.-strikc out

9Kng William Street, Adelaide, South Australia 5000. .3blce, ~p4 aus tihe v~enn

iedLby7 Da( cd this 2~ day Of 19 80 oet ufft

~EIY ATSerge A. Scherbatskoy '6W 11-3

APPLICATIN TO BE IN PIESONAL NAMES UNLESS 13Y BODIES INOPORATEI) BY LAW.

195242 I within

us in- (OkiGINAL) f said

mission FOR OFFICS.E by a

'a c~ien'of fle United States

~BOREHOLE~ MEASUWREMENT -,WHILE DRILLING SYSTEMS AND METHODS 'Serg e Scherbats-ko-y

P o -Ii .Box-1936, 1100 Everman Road -tW6th,,',Texas 7,611 U.S.A.

do~ 'sdemiilyand sincerely declare as follows:- L the appicant1.1 for the, patent/04tat-of- adun (orp, b ase of an application by a body corporate) (oder imi Falle' einer Anmeldung einer juristischen Person) m/W ar aul~iiied by- the ibz~ c /-patent of--addition

The basic applcation as defiedl by section 141 of the Act was/-were made in the following country or countries on the followving date(-f,) by the following applicant(-s) namel:- pplieatioii was i on August 21, 19 79 a te and full Serga A. 'SchErbatskoy facs Landes in de in .undarimcih Lng b d.,s Datuni A~t;iird derldie i14amnen dts/der in sameder.by of -tual or~s).3. I am/Aze- the actual inventorj-ftof the invention referred to in the basic application Name desIder cn Crilodues). (oweoapr-o-te-bn -the inventor is tbu appliao- (oder wenn der Aninelder eine andere Personals als der Erfinder ist)

Serg Scherbatskoy

tss(es) of actual Or(s.. so dcstderselben. of P. 0. Box 1936, 1100 Ev~irna-n_ Road Fort Worth, Texas 76101 U.S.A. inasner in which :ant(S) derive(s ros ,actual is/.ar-.the actual inventoe(-s-) of the invention and the facts upon wvhich the applicant(s) is/are entiteei to ma ,ke, the applicatin are as follows:- tle lassikneic(s) of

7c. durch,wcbencr i "d dierldic Idier bcfugi sind den dci iFrfindung 4. The basic application referred to in. paragraph 2 of this Declaration \Vas/wae the first e~nscigcntlichen. Irr7e,,erhai~ce" .ip catio made in a Convention country lit respect of the invention the subject of the application. cvptIiachigil eeigentlichen

iPredl at Fort Wor'th, JexasAhi I clay of 1980. 1ij~il 4-Sirlko Out arseslde of Sheet." A -able.

kai utrifft,

Se 1 e A. Scherbatskoy

,Sreet, Adelaide, South Au'sttalia 5000.

DO-C'MENS, LOG DWT

TH4-S. A .PLC TO

~P~ AU (11) AU-pB4.61,20/8 :ri ri ;i U- U -rl :i

45 LOGGING A BOREHOLE ,HILE DRILLING SER.GE A. SCHERBATSKOY S 6112 /80 5441 12 (22) 6.8.80 (24) 21.8.79 (31) 06 3526 (32) 21.8.79 (33) US. (43) 26.2.81 (44) 16.5.85 (51 )3 E21B 47/12 E216 21/08 E21B 21/10 i7 4 MA (56) 24860/77 513642 E21B 47/1.2; HO4L 7/02, 2'/06 491-83/72 473372 85.2 22739/70 447967 85.2; 99.8

(5.7) Claim 1. A telemetering apparatus for transmitting inform-

ation through a transmission channel from an appropriate

depth in a drill hole to the top of said hole, said

information being in the fc.:m of an information carrying

signal represented in terms of a reference signal which

is expressed by an associated reference function, the

operation of transmitting said information being performed

in conjunction with operations of drilling said hole and

said drilling operations being carried out using a drilling

assembly including a drill string and a drilling means

at the lower end of said drill string for cutting down '-1 rock in said drill hole, said drill string having a

passage therethrough and there being a pump providedfor i'

forcing drilling fluid down through said passage towards ;j

said drilling means ani then upwaids towards the top of .i said drill hole thus formin'g a drilling fluid circulation -I

.system, thereby providing a transmission channel for ,i y' 7:.16 1 16 2

square dil .erence between a desired outpuL and the mne.aa actual output, whereas a spiking filter transforms the chaue in the drilling fluid within ry j I, circuatibn system, said telemetering apparatus in- cluding a first means for positioning at the top of said

-hole and boin' operatively connected to said transmission

channel for d'eecting a signal which is expressed by a

fun tion representing a superposition of said information

cca.rrying signal and of an interfering signal resulting from at least one of said drilling operations, said inter- fering signal being expXressed by an associated inter-

ference function, a second means for generating one of

said associated functions and a third means for storing

said generated function and combining said stored function

with said superposition representing functionI to obtain

said information.

i

i II .1 i r r b"

i; r ;Ir Br Ih i-

'lFurther aspects of my invention concern improve- rnteis involvifti the.; power supply 95 and the power drive

APPLICATJIN TO BE IN P1RSON\AL NA:MES UNLESS BY BODIES 1ICORPORATED BY LAW.

NTS ACT 1952-62

SPE CIFICATIQN (ORIGINAL)

FOR OFFICS A41 A'pplicatiocn Number: Class Int. Class Lodged: 61 12 08 Orm~p+je Specification Lodged: Accopted: Published: 1 I ct4nen ,k (UiI~j~sthe Priorit'p 40

JS~ C4OITeC, fdk 04i

TO BE COMPLETED BY APPLICANT NaWIVt Applicant: 0 4 SERGE A. SCHERBATSKOY

Ad54 of Applicant: P.O. Box 1936, 1100 Everman Road, Fort Worth, Texas 763.01, United States of America

Agtuqlj nvt-ntor: SERGE A. SCI-ERBATSKOY

Address flor Service: care of R.K. MADDERN ASSOCIATES, 97 King William Street, Adelaide, State of South Australia, Cormonwealth of Australia,

Complete Specification for thie invention entitled: "BOREHOLE MEASUREMENT WHILE DRILLING SYSTEMS AND METHODS"

sc rlpion of this invention, Including the best method of performing it The following. statemnent isa ful det' known to m~e.

imi Street, Adelaide, South Australi'a 5000.

This inv'ention geneifally pertains to measurements whi-le~ -drii 11rg a bor- hole in -the earth and more particularly pertain's to sys ,pparatus, and methods utilizing hy-~dl~ shock w4a;,:,es in the drilling mud column for transmission of signals. representing one oT more downhole parameters to the -earth's surface. It also pertains to systems and methods for detecting these signals in the presence of interfering noi,:se.

a a a0*

a a a a.,

.01.

V

-7,

:the special teleina-try tool. *xs sChema ticai ly elec tronic circuitry

DesciptJOflOf the lPzior-, Art Th-Iis iLnvention relates to data trams- is:;,ion sy4tems forusein rasmitting data from- tiiC bot 011, of 40wel1

bore to the sw-facc v~ite drilline: the± v( 1. T has been long recognized in the o 1- ndu-,tr, tha t th-e obtaining of dJita f'.rom dow-nhtole Lt-. rg the drilling of a-weli. would provride valuable !,.nformaltiion whfth would be of intem.-st- to the drililin opera*,or, Stich inforn:ation as the trite veigh:' on tlt bVt, the ncintion adbarint- of tlbe hore-hoe, it ool f-t c

fluid prestre, and pcin.'a~te w bc ,or. of thv ho3 and the radi 03cti V, t y Of .fl rr.~oufldif, Lnu or being encountered by tho. drilIl b* t..ould i be exp.esse'c by quantities of inter.sA to Lhe "rillin, raLor. A number of prior art pro;)o4sal, to st-.rc he'qkmn ities whil e dril iint. and to !trnnsiu*L t h. 1.is ;U 1.0 he surface of the earth havL- hot.:, V'o. trans iss~on schemes have been, propo.;ed in Ltl,- pIriof Za.- or so tloin, Vor a descri ption of priLor ca-t, s, f. or i n c, CQ U. S Patent No. 2,787,705 is..-ew lu 3.J Arn V. Pate- t No. 2,887,298 issued fo P fD. iip t:a, 1"S. P: t.ulinw 4,0-'/L3,620 issued to V&tSLIJ, v*t 01, i~r

No. 4,001, 773 ismied to A E. LrwA- o P Pat-e-t i" I.

,964, 556 4ssued to Marvin Cc arhv<t et 11 U .S Pabl nt No. 3,983,94&- iSSIued to Jot-, and Pat' nrt io. 3, 791 ,043 i!.sued t~o M. K. Rki!, c, 1 All of" tih a!buve listted pat(215are inc orporatc-d in tia.-cIfctLn reference. perliap.. the 1was tro~ no. c) e.;o pr i r a-rt p)roposals in L practical sc-nL)". 1a." Iwen that of si h a]ling by pres Sore puilscs In hE-u dri 11. n i ii.t v. i o

quch mud ViA, ation.ielte by c s ice I, on Of Ohe InIId fwcircuitL by aIVflo 1 0otriCtiW, VflVLI L ap r1ra:l o~ CLQ11Q ir Lh, i intud r 1y l;t..a rlIL*I11s Of a Ibyp i Jro f IO i.c [1 t1 tie fsi( 0

'4 ~2

olJ che drill string (-high ane the annulus around the drill string (low r>:-side). Ir has been siggested ir. or art _o produtce nuid 'pressure -pulses by -ncans of vav;thav. woul d eithe-r restr1ict the mud flow7 inside the drill.sr 4 o sonie flwto the low pressure zone iii the an,.uu arf the drill string. Such_% alves are of because wlien used inside the drill stri:t *tk '_v musL control very large ;.ud v;mv Uv W V: A. control a by-pass, bc ilfthe- vye differences, th Iava w., motorized valve. F;& TI .interposed be_-ueen the annulus prod,':ctu in z :r 2 'L'S k

slow descrea.,.es Pnd- s_)w i were wubsequentI: y In order to of a slowly act.inL,~ooz T 4 0 prior art, reference nud 4.,

opening and h ?ci' of time. h. rr?:' absei'ssas; in Fist;. hr'j~:e. ordinates r;cs::tL k SO!) Rs where S0i5! tho W ;irC 24.

the area whic!' i I- C'S:

of opening or io.i: valve was cl ed3 'I(

The times involved in t hi. a. follows:

to Open;

b -0111 thie Ii 4. 2~ fully

opvn;

of the pum~p (when several puimrps are used the pressure

O was the rim e at Mwich the v i1ve started

to closq;-

Jv) OD was the tim~e at which the v ilve was

fully closed.

The timre interval:

(v AV) t(v) a b 'ad C

T(a wvill be referred to as ihe "Line of ujiondng or closing of Che valve". The ni z~crvil~

(v) o; en flow". Th~w, T will be ref erred to as the "t i:v K

the total period of tht actunt:, of~ the vz lve w~as Q t a 11 In the above atuetp;n ov Inv T Ueo-

lr~)"2 srtondn and consc-ouenv1\' the tota. AM~C Of the b actuation of 9 ~1yese r

latively sloyr openlni> on& i-1 r~s Vd the pro- dosed corve~'pwn!in6)y 31,w decreases an~d i'~ertases of mW-~ pressure v!the s rficn cf Lhe edrth ev Fig, 1lB). it can be Fvwn Ath~ thr presure Aoreased froti. its U )rmfal value of U r vxa:4 1000 psi w hen the valve was closed) to it.s Iowtst vnl' A 750 psi (when the valve was ope~n). im :nvol 'ed inA those ob'servedl pressure variat ions wern an follows. t S 0,O way the tivn. at whi~ch Lhe 7n.d pressure st arts IAI to decrodz;( frow its~ norma level at 1009 psi; t(s) OF was the L~ima at which the Aud pressure lbI attain~cd its lo- it 1, vel st 70? psi and was miaintatined at this-1evQ~ until time Vt 0G 1

~Fig. 16 illustrates sichen.atica1llv certanin opurJLtxcn., Ipelforted by a pulse shaping filter.

~4~4 .4

G vas the time at which the mud pressure starts to increase; Li OH was th- time at which the mud pressure attained its normal level at 1000 psi. Thus, the pressure decreased during the time interval

1) t S) 1 fs NO then it re-iined constant during the (0)I rse~o t 1.flk.erval T21C t and then it rose from its a2 a

dpressed valute to the normal lcel do duriny 'he t im

interval -u he z 1 ruf 0: 3 Id i the mud f low thro jh Lth vi; ior s irie 1 actuation of thv valve

TL 3: rarl t I_ I have designated quo" o i" Fin A (such as

t(V) 0 Q) JN t 7M (VN nj T ith1 super-- a b c d

a, a~ script to indicac that thesc aunntitlw relate to tht a a operation of the valve which is below the 2rf-ace of the I~sN t earth. On t he o! ht-, aY I)a Lid t L i A(S) C) ()i)ae

Afd T" 1 A" 2 W'1 and 05) r fit. r nfc dsignate

with superscripz te imndica i!ttht thh., 1"artiti, 4.

relate to measurements at Q, nurf.t W zV, earth. This distinction betwecn the quan' l U s provii0 with super- script v'1 and those wit h supe raupt W is oss;ent jal in order to fully undersi dnd some of the Qfatures of my invention. It i- essential..P thi; -nnecion to distinguish between the cauise and tuc effect, or in other words, between the phenomeha occurrinr' dow:nhulu in the proximity of the valve arnd thosn he dk'uiror at the surface of tr' earh. An nsesna1L feai. ure "f the vvi ow, propesea arraigeieuu is based on the relition';hipst.

ow" 0 D -4 l r 10 n, t ins r'4 rinA

2 =b.

These rltosisshow dwc etthe periot.. de' or increase of the pressure at Lhc, earth'.-, .;rxface va:,t same as the correspoiiding period of opening and closini' of the valve, and the period at w,,hich the pressure wa! Sukbstantialvy on-Lant (at a decreast-e 1&v(K) w t;) sa ,iue as the p--erio&d diriint which t y-evalv

opeln. words, the da~~Zld Inohe ~a a -a.

crease of nud prtcssaure a* the tar,. 1- mh wa in exact correspontdence with the ve nj-ar:c' s of the %avie -i mlt07I! laronsips(6), and (S i 1 be i

is this specificatioi- as relarir.-tc vaariarions sre a Tiemeir( of sle.; pressujre '.ariw' in the prio.- ,rt w~as fnot >uitn Yr I'tt ;*4

i) s veral hLe a .I r~

t- tzte "o 'stir facaa: ~then~dc~~~ x horv- fl ha.) a t U.4

n~ i~nge ii

ter con, a: i:t'hj-e

Si fLf' N* L .A I c Ua a~C a

Iat, s-ui a td inPtthc prlor 'i .U

44I.4,4. DECRPTO'O APAAUSFO DT

iT~lOTRANSMISSION WILlE DRILLING Su1b

Su 1 mary of the invencion Somie o2f che objectiveN of m3. iOv~'n-r "-V aLOMO by usinig hydraulic shock waves Ocr ecu inforimation MTile drilling is in~ pioc' waves are produced by a very rapid~ practical purp~ses Mus~t iUnirtlA""A valve itherposed between tLhu WO u W:; and the annulus around the -1 4 pass valvc suddenlyv opvnn th "7 io vicinity of the valve eyp alziost. instantaneously 4

4.

generated. and ronver;', S

*clcozse, ar pos it7i v 4, t4 S. of rod col.: wy~v

is analvgn- w the W& k 1!w4""

a "a,

5' (See for Nwno Joh 5' a Prent ice No!! Inc_ yv. i

genraio and do t: i w shown in~' F:Fq K 'Ai.

"n rW :jtr- -e

AC# 4 da h~ 'o

Vr"F~s

K F-aI :i

The first thing which should h noted in examini-ag B a Fig. 2A is hat the times of opi:i and c: sing of the 1 valve in accordance with riy invvni-i., tr( -veral f orders of magnitudes shorter than th( :;vtij. ding times, obcained by means c~t the rictt as re- ported in connL-ction L:iti rY.i

Previously suggest e (asT

second where,.'s in accort:d'*c-e in': in

Fig. 2A onc hno 17

uation applloa ,c C

remains opc

(ag in FiF. IA) on' d U x

Ei.2A s Ti t i( r :he '.ral:. ,r:

in Fif. 24 T C -d 'c

3S t!;5~l 1" B

Ir~rs;t~~t :i:r ti -7P~

4 -&I Ve cl f. I z LC i Aa *3E c, r. r: ;r C:

o f rii o jr

'414

f thl"e iv e.v O)I~ r

For the sake of emphasis I wis~h vo repent that in the prior art the opening of the valve producK a single event namely a decrease in pressAre and the nwlequent closing of the valve produced an:hvtr sirilp e: nt an increase in pressure On tLA other h P vention the fast open i n of thec val ve in T produces two events: a rapid cV.reaZsu no. increase in pressure~ (nc'gat :vu ,nl1sc This is in contrrast to A u wv:s. shown: 4 F. n 1B3 where an open~nr an. a :11b: ;4

is required in order to vvwCv'..;v" seq uen t inc rva-~ 1U t.

cl.osing of thet v~lvc as. in

and a subseqzuent 44 lt z C 7

pulse~ as5 in Fi. 20. sa sequent decrease ir P rangements sugiestv it 4 r tion, tberc ;ure tw sh. 4 d. operation of

"valvC wavtct'.Pr waveier have a ast, and are of si do

The tiwru L

ON th 11 0

I~l

t ON is the time at which the positive pulse 4 decayed. The time interval Ts representing the "lenh" of the' n

negative pulse (or the posi Live pul.e iF l0O

milliseconds, whereas the time interval Tm frou the

appearance of the negative pulse t, the :kppe; rani c of the positive pulse is 110 mrii iswcond-. 1hun:;, the total period of flow as shown iv i. 2r, ;F.

=3 Ti) 14 U n W.

is 210 milliseconds whe:cca t tLu:l poar~ o 1c.,

as shown in Fig. A oct 1 5) wan seconds. The graphs in Fij',s IA, 1b, 2A at! 2w K ve bo simplified and idraiiz ed by C' flminfl&Lifz rippit, ud Otwh extraticous effects. It shoul also be Pat"O Fit, 2B) that valv, in i* Icas! ther bypnow,;i I*1

the timc urvai Wn i I1 L W't

interva3, there i a vsloprt tv h eliminast- at the. to:in ;AWLt by W ip;! e filter. Such a pi ,sur'v dccl]i We i, i t he graph of Fig.. it shculd Asu be po i M ta .II A- values attached LU Fig;. ?'Arind A e jj'i n ;.rciy a .:it, example. These valu'tes shouti ni1t be iWerprotol a restricting my invent i on tOany pnrny ti c or v a t ivvn. The proessa as cxplainod in; coonccoiwn YiO V' A and 213 will bc rnc-ft*rdc'd to a: rclsAin' to imu t hydraulic shock waves". Thu.;, a disti.,icLi i:, between the r,jmo of hdlrulici Ono "vvv Iigyj. 2A and 2A and the regime of sI var i a: onK. of p ressure as in Fig. lA apld lB.

M1-

By providing a regime of hydraulic shock wavsI obtained a telemetering system by means of which large amounts of information can be transmitted per unLt of time. Such a 'system is considerably better adapted to s;alisfy current commercial requirements than Lhe one whi~h is 4

based on the regime of slow variations of pressu1e. The valve, in accordance with my invention, is operated by the output of one or more sensors for sensing oae or more downhole parameLers in tace LO0 earth's subsurface near the drill bit. One singie measurement of each parameter is represented, by a succession of valve wavd lets. Each- valve wa-vc-eet_ corresponds to a single opening aind clos-1rg of the valve., The succession of valve wavelets (which represents the us(e-ful signal) .,hen detected at the earth's -urface is usually mixed with various interfering s[L-,nals such as those produced by the operation of thr- po-mpafnd by other 4.drilling operations. In a typical dri1..~L ri-ngeent

a large pump located at I-he stirface -Is pum,.p drilling muid down t he dir ii1.1 r 1t~ Li .1l and hack to ttui-Sur!face byV Vuy Of MannA ~ente I l~L dril11 pipe and the well bore. Tin. int.'rferi ng etfects du-e to the puma~p arc, eliminated in is invention by i process which takes i iito c eoutit tin periodici ty of These effects. Other effects :isso,. at ed th rJ iL n" Opera!, ons-,usually appear as no. s :igi compris iig ,arel~ti vcly wvide frequency se u.Th is nuis s igna ili s iiisome-ins tances white noise and in at her i;I ocsit dcTarts consiucrably from whitce no.'se A dig iitrL ysLeDJ VS IW11 iC-1m ayV

be a matched lFilter or i us hpngi or a spiking filter-i s emp L~eycd to iremyove the no iso nu U imatched fitteor mxu hesign.,l Lze Lo n F-1c .Urt ic t7 Thc

reception point a ul s shop ng ifi(er iinit. zeu; the

(wth scintlla-i~n apropiateelecroniountr

circitry an b. Al. arangd thse t genr4r

theflu4whic gmma ry

a DC voltage proportional to tegmaryfu hc

16 2

mensqaPdii _erence between a desired oui-puL and* the aculoutput, whe-,re-as a spiking filter tiasforms the. efu i. cgna1 b cntrc in -Ito j one wh:Lh is suf-

ficiently sharp) so that it, can di!cingueished against *~backgroui-.d. noise-. A special- technique i applied to adapting these filters to the ohj cCL 1705T of this invent on. Such a techa iqod require-. stOrag 211A sSeCOLient. re- produiction of reference r ignals. The first re- ference signal ics a wavelet piroduced by t-he op~ening and cl.lo sinig of thle ;al ye avncd 'he s c.,ord ref.'erenTCC- gi.

represents noise cle toc t'he cir ilj i g )perati ns. Detec J on and s torage Of the first cef[erence ~i gaI ob taied Z3 by removing',' the weighr Or) the1 h-it an uppng z.iU the P.ctual drill-ig (but ai Laillillg 1 niw pu. p Ilf:in norma. a cin). h s, a si goaci h i t i Ich is, freeL from the, ambient nolise. Pe ction thy(. second 0"d~u~.uo reference sisc Is oItS '20l I 17 nt 1i Iu. 17 S during a per.,-iodl of timre ,,ihen wiv, Lu Va J a clo sed. An appropria ria'1di t al c npn t i ig L v c t 1- 4i Vrug~d

4 the( datt Lr.'n ij n; on C or1 lc J)Jt 11 1l i

s:Lgnals a:)d 0d v e, J_ fro:ti lie t j t'I iii L YUft oct iof)

or for the I'.iof Lu One i of miy ii vn l' i i ccir Iei ian roverlnent1.; nvo lg 41-, C! e u nr) o I vt V,II s 1 1.y 40 of t-1e1, Speci;al tL c'I(Ti LrV toolI 50. Another ofmy OpF' iunvetion concce Co th( i )C 1lC a pe ci50 hydrau ii cily opperatecl mchmoic arang-,'oI tlci. w ill pfri od Lcaliy po'sit ive 1v y O hc i t i he Cc)Sc! lP 'II 0

In adi~dtion tiC'is C'(1 I ii ht will inhiibi t. opera i.ji of tLWr val yec 40 iii f' anl 'CL 0' e1 t I' Ci I I Cr i) TP' 1i(2 c

'4

p. A ~i~7 7 rtie a pects of my inventiont. con( er imi-prve- inIvolv'infg the ~power supply- 95 and the pow.er drive 10:4 of, the special f-elametry tool. 50. Such improvements SL to great:'ly i-ncrpease the number of' satisfactory val-ve actaios.taial ithout downhiole battery re- el arge, oD-1rep~laceuent. Aniothe-r as, cct of, my invention concerns ipoe mrits in pulse time Ccdes Wherein oly shortplsso substantially constant duration a-rc trans-mittcd, and the t-ime, intervtils, between succe~sive pulses are the measure~s of thie magni-itude of the relevant parameter. In. addition there is disclosed a, system, for improving the precision and -accuracy, i'n the transmiss-ion anad detection of mud pres, ure pulses generated at the dowrnholc equipment, which system involves the generationi- at the dowhole eriuipment and the transraissian of a. group of at least 3 unequally spaced mud pressure pulses for each in- fctmation carrying sii.igle pulse, and the provision of appropriate ocquipment at the s urface for detect iig 42 and translating the transmitted pulse g!coups. The novel features of my invention are sct forth '~rhparticularity in thie appended claims. The ini- ven~i both as to its organization and mann~er of op~raionwi':h fr her obj ot 1ys and. advan tag es thereof, may best be presented by w-ay of illustration and examples L) embodiments thereof When t:Laken in Lon- junction withI the accornpabying dr-twings.

13,3 ef o o'r ,i

"Firef the Draw-ad nensc"1 eciption of Prio

rt". Th e remaining,. figures, as well as Figs. 'IA, IB, 2A, an-d 2B relate to the poreions of the specification entitle-d "Suimmary of the In.-vention" and "Description of the Ft-ef-orr-cI Embodiments".. Fig. 1A shows schematically the operation of a acting-valve as was s-gested in the prior art. alo s v00 s g

0: 0Fig. lB shows schematically pressudre variations detected at the earth's surface and resulting from the. -peration of the valve as shown. in tig IA. Both Figs. 1A and. 1B describe a conditiLon referred to in this specification as a "reginie of slow variations of iprcssnirr' Fig. 2A shows schematically tie operatiojn of a fast. acting valve ii). accordan.--ce withi m1y invc"I~t Lonl.

Figr. 2B shows schemtically presssure vairiati'ru; detected at the earth' surface andl resu].ltng from,.

thc o pe r a-Li on o f 't hu v al ve s h o 1! in Fig. 2A Both mm,.F-igs 2A and 2B cCsc-crihe a condi t icn refer rue tdo ill 'this speciica tion as a 'regijme_ of- iiykdra i chocl. wv Fig. 3 s cheniatically and genurall y MAL.S tra tes at well drilling sy stem eqntpLpe 1iot si_'lt 11dill. and to make meaSUremetnts. L- ccordlance with ,.,rie aISPectS my in-vention.' Fig 4A shows SC)heiLC~i Ily ;I vW' tion o t hU Sub1- surface equipmenrt inc].lding a. sp!,'ci dl telewe try tuol iLn accordance with± my :invn on; Fig. /IB shows schemit icc-I ily a portion of the a'rrange-men t of Fig 4A, Fig. 5A shuws s-eaI.Icii~ nd inoi L. injOLr1th 1 i '01' mc: 0C ro p4 4ee k: *1 ly co-. 'rip ed i I dotted rectangle' in Pig. 4A. ig~. SB showis schunutiically powr j)Q0. ujj'Iy !ncl Liding a c ~pac~~l mV~A ort: ig ml1i*'. mrgii m a itioiir n f'or

p c l t c CLt't.I..C L U WC 4 '11( MItl (J1e vke Q~elmer tool. IVQ~ shematically electronic circuitry which aPby -'ilifed to accomplish automatic cut-off of. thie ponyr 6rive for the valve of the special tele- e,rhy, tobl. Fig. 5D a~d 5E are graphs to aid in the pglaion of the automatic cut-off for the signalling vailve 'power cdriv e. 6A, 6B and 6C showq diagrammatically the Figs operatibn of hydraulic "auto close" of the signalling -valve.Z NOR Fig. 6D is an~ engineering drawing of the arrange- t shown in men Figs. 6A, SB, and 6G. Fig. 65 shows schematically an electronic "fail aae" 'arrangement applicable to the signalling valve. Fig. 7A shows schemtically the "sub" and! hous Lngu sstric tur e for the special telemetry tool. F~ig. 7B3 shows schematicaLly the cross--section shape of centralizers that may he utilized with the 4, structure of Fig. 7A. 'Fig. 7C shows schematically spe'ci al conacrvLor w1e=,:- that may be ut~ilized for joining the sub-scc:~ ns ol housing portion 250b of Fig. 7A. Figs. 8A to AE show grapha representino variaticnc, of pressure as measured at the earth' s surface and (V) corresponding to various values of T a (ti[mC"i of Open- ing or closing of a valve) and of TO) (time of: open Ntow). Graphs in these figures show results of certain tests which I1 performed inorder to obtain t~he- optimum condition a regime of hyiranlic shock- waves. More npecicfical ly Figs. &A to 8E can be descr~ibed as foLlows:

8A coureponds LT soon up T (v) Fig.

2 seconds,

5 813! carrsponds BB to T" 200 mllIisvuonds and T~v) Abound'.

Fig. 8C corresponds to T 60 milliseconds and a

T( =-0.25 seconds. to -T 5 milliseconds and Fig. 8E corresponds (v 10 seconds; b Fig. 8F shows an exact reproduction of the pressure signal showing a valve wavelet as received at the surface from the depth of 9,800 feet at an actual oil well being

"°O0 drilled in East Texas. Fig. 9 is a schematic illustration showing typical above

ground equipment to be used in conjunction with a downhole pressure pulse signalling device in accordance with my .iventionand comprising a matched filter for eliminating

random noise when the random noise is white. Figs. 10A to provide a graphic illustration of certain wave forms and pulses as they vary with time, which are shown'in order to aid in explanation of the operation of the equipment in Fig 9. The time axes in Figs. 10A to

Fig. 10C and the time axes of Fig 10D to Fig. 10G are

positioned one below the other so Lnai one can compare these signals and wave forms in their timn relationship

one to another. More specifically, Figs. 10A to can be described as follows:

Fig. 10A contains three graphs showing three com- ponents of a signal detected at the top of the drill hole. These components represent, respectively, an information carrying signal, pump noise, or in the case of use of several pumps in tandem, the noise from the group of pumps and random noise. Fig. 10B contains _nree graph -showing respectively the delayed information carrying signal, the delayed pump noise and the delayed random noise. The delay is by an amount T representing the period of the operation

*of the 'puqp (when several pumps are used the pressure Vjariqa:ions~, although -not sinusoidal, are still periodic because the. tan~dem pumps are maintained rola Lively close to being "in phase"). F-ig. 10C contains two graphs showing, respectively, differences of the co-tresponding graphs in F'ig. anrd Fig. lOB. One of these graphs represents random noise while the other iaph r represents an ini-formation carryinag signal. joFig. lOD shoasa function represetinLg' the output of a digital filter or of 'a rcss-cor elaior in the embodiments of my invent ion. This funct ion is sub- stantially similar to chat represtutK the i nf ormation carrying signal in F'ig. 10C. The cdigiltal filter used herein may be a mitchec lilIt(_-,ulio sYining filter or a spikin.; filt~r. Fig. IOE show..; a I nct i. ,,i~1hlar to th;,_of Fig. iOD bur- delayed in tim- Iby L2n appi opr lze mt ervall Fig. I]OF shows za.funotioi !h iriGIE buit reversed in viine. Fig. IOUrC(;n. <';Of Fig. 10D and 1.0u r. crJ sniv to pulses tL ±t oc, _i-v r, 2. nh 1r7p

performed C~ti ~>r

.scoring an i2v~iI I~O O

a noise signil. Fig,. 1 3 ct.. Y oL ionl t be :,"ove prouticl equipment emri nt~ oC~~l;tn Fig. 24 hp~shi'.t ii, abo .U ground ecju i t coip r i,,Iw a c, fill: vlimination 2a' timnuj -I .c xwhi t e Fig. 1 sliows scho!!at i en i :j port ion ofI the abovu gr(,und equipment which con! ai nl a puAlse sh tpingfit.

Fig. 5B showas sthematically a power supply which may be incorioorated in the power drive 104 of Fig. 4A

~Fig. 16 illustrates schem:atically certain operations plorkfed b~y a pulse shaping filter. Fig. 117 shows schematically a por tioi Ai the abovo g'rounid equipmnerit compris2 np 'a s i f j i r(-r kv.Th-rein a,-spizinig filter is used to tra~wfurw a dn. Y avle into a correspon-ding pair of spil-es. F igs. 18A to 18F show six pissIilC ch ~m for a spike lag for a pai r of sp i k as prdu J YV MO of the arrangement KC Fig. 17. Fig. 19 shows schemaut :aI pA I i grounid equipment compr~isin a i

a spiking filter is usci to trat. or .i in

*wavelet into a cur ropnn P. W pv, Fig. 20A to Fig, 0O F>r. lX ~'K for a spiku lag fo a. i. t ,nl

of the arraiy ymen ofY Fig. 21A to Fi"

time deiayp. M~oro sp. t i AY.;

to a debu nlk

to c;

determin Ot p f Fig,. "C filter P mny vaY durat ion

parameter P of a length (v P Fiv.

?th and VIV-' Fi hnn C.- VL inacr~cr.-

AS8

Fig. '26B shows schematically a pulse time code -syw 'off my invenitionl, wherein the magnitude of the parameter bcing tranrsmitted is represented by the time JneIa betw-..een successive single short pulses of sub-- staffLially constant time duration. Sig. 26C further illustrates schematic-ally tL P"Ine *timfe code system of Fig. 26B. Fig. 26D shows schematically a pulse time code svstemr of Qe type shown by Figs. 26B and 26C but wherein "triple group"~ pulses are utilized. Fig. 27 is a schematic block diagram showing o .4 at ''Code Translator" utilizad to enable a sys;'am 7u rcceivv- .4 4 0 4 4 signals that are in the "triple group" pulpy: time code form. 0 al5 Fig. 28A is a schema t i blook digc: n~ ig 4.4 -ciiitry of the selector 316 of Fig, 27 ip frth r dc:n'] Figs. 28B, 28C, 28r) and 28E are ;rap ic aidi enplanation and understzndin, of Lhe wpuratn o:f th circuitry of Fie.. 28A. Fig. 29 is a schetwit blIock Na0 a -lt N cirsuitry for gc'necati-,:- th in Fig. 26V Fig. 30 is a 8;chiti di~i siown pvi of circuitry that can accompl is 4;b pal- t' CIA

of my invenLion. t ~It should be noted that i rical rti~ wn~y!, have been appl ied to s imivi Meot -hov. iv. !n o! the above fi gures In s;uch cases t he decy':t on an82 functions; of c~hose elenr (w221 'il*1 t ne re far as it in unneccessarv to voplin the w) these embodiment.

Description of whe Phreferred Embodiments

1. OENERAL DESCRIPTION OF APPARATUS FOR DATA TRA1NSMISSIOM1 WHILE DRILLING

Fi-gure 3 illustrates a typical Iayowi of a systec. embodying the principles of rhis invencion. Numeral indi~ates a standard oil well drilling derrick with a rotary table 21 a kelly 22, hosc 23, aL.J standpipe 24, drill pipe 25, and drill collar 26. A~ m.ud pump or pumps 27 and mud pit 28 are connected i~n a conv t tional mannrr and provide drilling mud under prtzssure to the stand- pipe. The high pressur( mud in :p.mped dq)'z the dril string through the drill pipe 25 and the s<arndard drill collars 26 and then thi o-a;h Qw s2toc al tveetryv ool and to the drill bit ThL aril:: V; 0 in. PYOVided with the usual drilin 'on QWx shouw" ngrdma:.icnl ly by 33. The diomtctrs of the col. 'a42 he teien.eLTy tool 50 have boonr shown largo anm oat of. poporto:. t,; those of the drill pipc 25 iY vr~i ton, cearlI-: i Ilustra~ t the me~h:.

arrows an' the: .Q

rhe drill pipe avjp*I Welle ut e. Ujkv. reaching the P ;.oiv,::il i the mud pt (by pil- Onin and ocher- well Wd nir furthec Piltered K&'L teUa, recircuslate4.d by; tau n pm 4, v i ofC ia. Interpose'! b.etwe~n :.vni jl 4 an'! 2.6 is the special vc lIvorterint vel eretry tool des it~na~v Vy !n:

in, 2 54. which coat aiu t V.al," va.lvy 40, an electronic proc s sir, ariembi<. 96, an,2 st-osors 101. The val~ve 40O i!;deto i ed to nar: l.' by-pass so,, of' Qc mirom th Q idC 011 SO dri. collar into :He annulus 63. Nor. .1ly (when the valvc is closed) the drilling mud Wat all W~ driven

Chrough the jets 33, and conseque;'tly consider We mud pressure (of the order of 200Y to 3000ps is p.reven~t at the standpipe 24. When uhe vaive Ati y (3L the command of a sensor 101 and VI' 1e kii MAL S- 96, some mud is bypa~sse~d, 0w tot.: r, moment wrily decresed, and a pri. !ir ch-- c detected at the suandpipe A4. The econc assembly 96 generates Acodd sequencr of elec r ic pulses representative of he parw: tter beiei by a selected sens~or 101, and corrpcwdng op and closings of t~ c va~vc 40: ar ;roK e w:;r he~ consequenu corres,;ynin ;yrtsurt vnov zi S~~d1'. pipe 24. Numeral 5! dw"tc prv, ti. "t generates ceve.,; i 'c r :ca chainge. 'pZ in~ zhe sr~np; r. Y tb:

of these p ;ai c aSS

onI

c of

I 4 4

Oct 1

contI -I.

"Job. I heU( explained later iin the sv smaller diame~ter tha~n Owa wppn. s.

in Fig. 4A, the dril inl; mudI( crvi

13 telemetry *no! ?50 zrrows 65) t hrou. :4v it n .Mt

shown by the. aron 60ivz"1

ass~embl.y 47 onn:r" v v,

'zTh vav :rv Cni on!2.

thatth rS vlof

lag!A o,%n c

.1.

-aI

a

system descr~ibed in connecLion %Uih Fig. 6D. As an alternate arrangene~t in Fig. 6E. the relay 306 (w4hich Af course can be an electronic switch comn-

Doubble acting electromagnetic solenoid 79 is arranged to dpen or close valve 40 in response to electric current

supplied by electric wire l:ds Let P60 indicate the mud pressure in the annulus

P7 the pressure in chamber 77, and P 78 the pressure in 7

chamber 78. Then, when valve 40 is closed, one has Pg

P60 When the pumps 27 are running and valve 40 is

"closed", or nearly closed, and P 7 P78 the vlve

stem 68 is urged towards the valve seat 69. When valve

"6 40 is in the "open" condition moved upwardly in

the drawing) flow of mud from chamber 77 to the annulus results, and because of the resistance to flow of the orifice C tFig 4B) one iha: L relationship I'7

P78 P6 0 Chambers 83 and 94 are filled with a very

low viscosity oil (such as DOW CORNING 200 PLUID, pre- ferably of viscosity 5 centistokes r less) and inter- connected by passageway 86. Floating piston. S: c'dusces the pressur' 8.r At i 1i 5bc0 no iK

equal at all im to s all Lime.. P

2b P83 84' 8 Therefor, :he valve is "ope:

since P78 P84 and P P the valve 40 is ured

towards the "oper" po:ii un b .a force (area B) (P 7 7 P84 The valve 40 can here forc be termed bi-

stable; when "open" it tends to remain "open" and when "closed" it tends; to remain "closed". Furthermore, when nearly open it tends to travel to the open condition and when nearly closed, it t::d to 'rrvel to the closed condition. The valve 40 can therefore be "flipped" from one state to the other with relatively little energy. Thevalve action can be considered the mechanical equiv- alent of the electric bi-stable flip-flop well known in the electronics art.

-23- J I411

Fig. 4B shows the valve 40 in the open conditj n, scintillat whereas, in Fig. 4A it is closed. circuitry') Ref.-.rring again to Figure 4A, numeral 91 indicates a DC voltz an ele(uf-ric "pressure switch"' which is electrically is interc' condi':otive when P 7 7 P78 (pump running) and e ectrically ItiW sensor to :on-conductive when P 7 7 P,78 (pumps shut downi not 95 of Fig running),. Wire 92 running frcom pressure switchi 91 to (electron power supply 93 can, therefore, turn the power on or off. shown is Also, by means of electronic countur 9' and olectromiagnevic2 Fig. 5A i ,j0 sequence switch 95, any one of the four sensor 101 can be a single operatively connected to the electronic proce.-sing ssembl\ supply 93 96 by sequentially stopping and running the mud~lpumis 27 4A are nc or by stopping then running the pumIPS in acc":rcance wiLh In F a predetermined code that can be interpreteu by circuitry to AID cc in element 94. The pow,-ei 106 of 0i III. DESCRIPTION OF ELEGTRONTC PROCESSING noid 19 ASSEMBLYPORTTON 01- SPECIAL TELEFM :IRY TOOIL ro that The oper We havc described the operation of L the L tabs e crates a- valve 40 and he. sequence swi tch 95 which rmhs the by 1-he c selective electrical connection of the various. sensors th o s en s 101 to the electronic* process ng assembly 963. output ca For furthei details of the olecironic p'wcoansinj' transmit assembly 96 referenice is made to KV 5A, where like verts ti' numbers refer to like numbers of Fig. 4A. measur3 r Various types of sensors At generanc, l ectri r of ordif signals indicative of a downhole param.eter arp '.AI ordinatc known. Examplev are gamma ray setso rb, tenpu:>iture 30 word.I sensors, pressure sensors, got~ content sens.ors, magnetic no expD compasses, strain gauge iricl inorl'wters mnnetume! ers, real ize gyro compa'-svs, and many others. For the illustrative \ariaAti example of Fig. 5A, I have chiosen a gamma ray sensor of hour such as an ionization chamber or goiter counter or 35 (for ex, scale o in seco

-2/i-

actual. current buildup when Lhe valve is no; block ed; in actual working condition (opening or cloving). 272 for opening, or closingks ace very similar. andt The curves It is seen that curve 272, aftu r Ct Np Iio*.tion cU is it rv- '%Ynl tn- 'radua I IY ri 'es K ,ir'c 'Iic :es; cc! iv#. hasz scitilatin cuntr-(with appropriate electronic circuitry). AI. these can be arranged to generate a DC voltage proportional. to the gamma ray flux which is intercepted by the sensor. It-is understood that the switching from one type sensor to another as accomplis cA by switch mechanism of Fig. 4A is well within t.Le state of the art, (electronic switching rather than the mechanical. switch shown is preferable in most caseF;) .ConseqUent ly, inl Fig, 5A for reasons of clarity off description, only a single sensor 101 has been show-n. Also, the power supply 93 and mudl pressureu actuated switch 91 of Fig. 4A arc, not- illustrated in Fig. SA. In Fig. 5A, the sensor 301 is connected in) cascade to A/D convurtor 10?, processor 103, and power drive 104. The power drive 104 is connecte-d t-o windings 105an 106 of the dlouble act ing solenoid des.Lgnated as solte- noid 19 in Fig. -4A. T-he vwe drive 104 may be similar Uto that showni by Fig. 3E of uh,- parent- application. ThO operation is as Follows: the sensor 101 gen- erates an oul nut. (C VC' riC n nalog; sigonal as rc,resented by '-he curve 1014ashown- On the 'raph iisanedi altely above th sensor rectangle, 101, The cutrve shows the sensor output as a fuon't-ion of the dt(Lh of the Leleraz~tering tranISui t er 50 i-n t hr borerhole. T1he A/D conver ter con- verts the analo,, signal off 101 1 ino digitlal form by measuring in suc'cess,;io the mag-nitudle of a larbe number off ordinates of curve 1 01a ant translating, each individual ordinate into a binary numbe~r rep.resented by a binlary word. This prcess,,, is 1 known in the art and recquires no explanation here. IL is i mpu(rtant, however, to realize tha!t whereas jgrciph 10111a may represenLt ihe variation of the signal[ from the transducer in a 'matter of hours, the graph 102a representis onue single ordinate (for example, AB of the curve 1011b) Thus, the time scale of the axis of absi ssas on Figure 102a would be in seconds of' time and the whole graph 102a represents

Sone binary 12 bi- ord, ,nd in actuality represents the decimal number 2649. Thus, each 12 bit word on

Sgraph 102a represents a single ordinate such as the ordinate AB on the graph 101a. The usual binary coding involves time pauses between each binary word. After

the pause a start up or precursor pulse is transmitted to

indicate the beginning of the time interval assigned to the binary word. This precursor pulse is not part of the binary

word but serves to indicate that a binary word is about to commense. The binary word is then transmitted which is an indication of the value of an ordinate on graph 101a; then a pause (in time) followed by the next binary Sword. representing the magnitude of the next ordinate, and so on, in quick succession. The continuous curve

of graph 101a is thus represented by u series of binary numbers or words each representing a single point on he graph 101a. t: It is important to understand here Sthat between each binary word there is always a pause in ime. Thi. suse (during which no sigaale are transmitted) is frequently several binary words long, the pause will and be employed for an imiportant purpose which will be explained later in the specification. b* -In order to permit decoding at the surface, the clock Nr. 1 must be rigorously, constant (and in synchroi.,sm with

the corresponding clock 212 or 309 located at the surface), and it generates a series of equally timed spaced pulses in a manner well known in the art of electronics. The graph 103a represents a single bit of the binary word 102a, and the axis of abcissas here again is quite different from the previous graphs. The time on graph 103a is expressed in milliseconds since graph represents only a single bit. Each single bit is translated into Stwo electric pulses each of time duration t anid sep- arated by a time inaerval t. Graph 104a is a replica of 103a, which has been very much amplified by the power drive 104. Electric impulse 104b is applied to solenoid winding 105 (which is the valve "open" winding), and

c'ur-ve is always positive except during the times be- electrlc1irpUl~s e 1 0'4 appliedJ to sO1_i oid 'windii'g is,

106 (wl-iich: is the valve "close. winding). The valve of Fig. 4A -thus-is opened by pulse 104b and closed by pulse 104c an-d, therefore, the valve 40 'remain's in th 6Op en." co-nd ition for approximately the t ime t. T-ha times t~ are adj-ust ed to be proper for cotrect act- uation 'of the solenoid windings Iand the. time t y is pro- portiofied to:open the valve 40 for -the correct length of time. Both of these time's are determined and con- troll-ed by the clock#2 In telemeteri-Lg information Zirom a sensor to the earth's surface, I provide appropridte pauses betwe -n A transmission of successaive binary w ords. Because of *these pauses, it is possible to store in an appropriate z electronic memory at the surface equipmnent the noise caused by the rilling 'opera t.ionaon (without the wavelet) The niecessary arrangeme-Lz~ and procedures for doing thi will1 be described later in this specification.

IV. DESCRIPTION OF POWER SUPPLY FOR SPECIAL TELEIVETERING TRAN SMI TIER

As was pointed out previouqly, the valve 40 o-f- Fig. 4A must be very fast acting, and to drive it fast requires considerable power. (It has been determined as a result of appropriate te,-sting that such a valve requires about 1/2 to 3/4 horsepowxer to operate at the necessary speed). Althoutgh this power is very subs ta.nthal, it is applied only very brie4Ely; and, consequently requires only small energy per operat 'ion. In actual opera~ion during tests, it was found that 1/2 horsepower app)ljed for about 40 milliseconds provided the reqilr,,d energy to producec a satisiactory single valve atue Lion. This eniergy can be cailculatted to b e abouLt 15-. Jotl es. A ba ttery p)ack that is suffic iently ;.nitll to be co ii a in dJ itt ii hiousing 250b of Fit,. 7A

I -7- lLL~i L.I I IyLIA u Powur anA. unvxgy For actuat ing

-can prvdeyroiat 4 4 millio Jols wtthou

oaupod Approsimael 15ilo Joules woerto.Th

ind11uctatwtv, the Q, and the motional impedance of the solendid win'ding cause the rurrent build u~p to be relativ~ly slow and along a curved rise as showrn in curve 272A of Fig. AC and 300, 301, of Fig. 6E. Thus the total energy per p.nlse is substantially less than Joules and has been measured at 9 Joules thus pro- viding a capability of 216,000 complete valve actuations. (A still'greater capability is achieved by use of the circuitry described later in connection with Fig. From the above, it can to seen that providing the nec- essary downhole energy from batteries for a practical telemetry tool is quite feisible. .Providing the nec- essary very large power (1/2 horsepowe;'r) howaver, pre- sents difficult problems. It was clear that the solution to such a problem would involve the storage of onergy i~n a mechnnism that 0 could be causid to release it suddenly (in a short time)

0 and thus provide the necessary short bursts of high power. One such mechanism was "hammer action" which w.as utilized in the tool disclosed in my co-pending appli- 0 cation, but which has been found to bc sometimles insuf- ficient Othir mechanisms consi dered earl y were the use of compressed air, compressed sprints and oth-ers. Capacitor energy Pzoorage systems required large values of capacitance: The energy stored in a capaci tor vanies as 'the first power of the capnaritanz',e and as the sqluare of the stored voltage, and sic lUow1;.ioiduc ance fast acting, sod enoid drive w'.indci ngs a ro requrvm e, the neesi ty 0at low ILu g duvi c'(s be cumu apoont i nitial calcul ation indica ted that uinly 1 argv capac i orn o be~ recjuir 'd.

afelfutherY evaluation, it appeared that an operab'ile. systec.m might be .feasible. By mathemratical analysi~s ai.d by eLxperiments and tests it rw.,s determined thaLt a set of optimum circuit parameters would be as foliobws: i. _car=~ Of cccn~id indl .1 henrys when in the aictuated poition and .07 'henrys when in the non-actuated p)osition a tapered armiature solenoid). 2. Re-sistance of solenoid winding: 14.5 ohmis. 3. Voltage at which ener,,y i~s stored: 50 volts. 4. Magni tude of storage capacitor: 10,000 mfd.

Current capability of d-rive circu' t 10 amperes. was -determined that ini o-rder to have fast sole- It noid action,, low iniductance winig;are desirable. lt was also determined that currcnt capabil it i (5 ofeJe tronic drive circuits can be inr' ve~wiI bv .ond ampe(,.r es. Low vol tage, howvever, requiraes untdU-I la1r go values of capacitance. Recentl advances in so called iiw Iein sa [t 1batteries have produced energy sources uf very o(wc(' &cnes The saifte recent technology has alJso dh-v lJopeC2 iaci f ors of extraordinarily high value.,, 10 f ajrs i n zi LIte space as 1 cubic inch. These %,ereunacceptable because the required heating to a high te-merature which was deeme,'d impractical; and the' cu; t w-as prub H I i ve. rConsequently, still further effoi Fts were reqnlJ:e'J. Followiag a thorough and le-ngthy inves tiga t i f i na Lly it was discovered that a tantaJum slIug capai~ i or Inade iaccordance with the' lates t ol e't IiTrtICncnI the spec~iiations if the other~ pn1):"ilc.tLealS anid i.

outlined, above wern optimized t-o mat i~ e ew te sti of such capraeiLtors. Pl'0Q111 the ajbo-ve 1.1- 1)0 ,-ct-n thi t at Joacc: 2 1o 000 czopete -val2ve op(.ra-tiLon.s can 1Lw e.1i zedi FrOi. rOMi. ha ttVevv charge. Assuming that the telemetry system can provide adequate continuous data by transmitting five pulses per minute, the system is capable of operating continuously in a bore hole for a period of 440 hours. It must be pointed -out however that continuous operation is often not necessary. The tool can be used only intermittently on tommand by the circuitry controlled by switch 91 and elements 94 and 95 of Fig. 4A. Furthermore, as will be explained later, when ad- vantage is taken of the improved circuitry of Fig. an even greater number of valve operations can be achieved. Operation at a rate of one pulse per second is considered practical. There is another parameter to be determined: the discharge. The 15 proper recharging of the capacitor after capacitor can be charged through a resistor connected to the battery, (or Cther energy source) but this sometimes proved to be slow because as the capacitor became part- ially charged, the current through the resistor diminished, 20 and at the end of the charge cycle, the charging current o approached zero. If the ohmic valve of the resistor is made small, the batteries would be required to carry excessive momentary current because the initial current surge during the charging cycle would exceed the value for maximum battery life.' The best method is to charge the capacitor through a consrant current device.. The capacitor would then be charged at an optimum charging current corresponding to the optimum discharge current for the particular type of battery for maximum energy storage. By correctly determining the charging current, a substantial increase (sometimes a factor of 2 or 3) in the amount of energy that is available from a given battery typo can be achievd. Constant current devices are well 'known and readily available el.ectronic integrated .eircuits, aid are available for a wide range of current

S i. Fig< 5 ;shows SB sahematically a power supply which

may b e incorporated in the power drive 104 of Fig. 4A

including a capacitor charging and discharging arrange- ment for providing the required power and energy for the windings ~d.aso of oid 79. In Fig. 5B, 450 indicates

a b ttery or turbo generator or other source of direct

current electric potehtial, 451 the constant current

devi'e., and 452 the capacitor. The capacitor is charged through the constant current device 451 and discharged via lead 453. The lead 454 provides the regular steady power required for the balance of the downhole electronics.

DESCRIPTION OF HYDRAULIC "AUTO-CLOSE" SSIGNALLING VALVE

SI have also provided an arrangement which will operate in case of a malfunction which could occur when the valve is "stuck" in an open position for a

long period of time. An arrangement for automatically closing the valve in case of such malfunction (indicated by reference numeral 269 in Fig. 4A) is illustrated 2 diagramatically in connection with Fig. 6A, 6B, and 6C. A was pointed out earlier in the specification, the valve is designed to have a hydraulic detent or bi- stable action; when opened by an impulse from the solenoid winding 105 it tends to remain open and later, when closed by an impulse from the solenoid winding 106, it tends to remain closed. It is possible that because of an electrical or mechanical malfunction the valve could become "stuck" in the open position. It should be noted that if such a malfunction occurs the drilling operation can proceed. Some wear would occur at the orifice 81 of Fig. 4A. However, the disturbance to the nmud system hydraulics by having the valve open for log periods of time is not desirable; and even thOugh .d illing can continue, it is very advantageous to h~ave the valve closed most of Mh time and opened only to produce the short pulses reqiru d Lo gen~erate the hydr-aulic shock wave In the diagrammatic (]rawi.nL: of~ LA, 6B, and 6C, the r6d 100 is used to push t he valve clos~ed by; exoyt inj; a forc~e dlownward on the roj 60 of ~~ocni armature shaft). Referring now to Figs 6A, 6B 6C inw 6D. the up'per .end of the mechanism i s exposed toNiljp u" mud under the hydrnsvatic py Cs :urc pj" the. Off er ential pressure across the hit;i pressure between the inside of P. :00 50 "no !he anowi us When the pumps arc not r~imP ;010 r..<lrtepup" the zone III is >iydrosttliC? o i are running, the pressuin h~li, A K a 11 ".di t Q ential. Since the difwv A cc C>UF h "f t :e order of 1000 t~o 2000 pi at the zone III when t he pui~ps ayi increase of 1000 to 2000 p~i.I) St" :d1 V pumps are not runnirng, .on. IN,2 Fir. 6A whe Fi'.

press, because tube in0'a 84 wLh.!L conLa ins oil it an :c 4A) and hccause the or i cc I1I Ktecoio. c, Viv ne- 112 and 113. Assume now t hat en pw oL syA.P h pressure in zone III t"Cn !nC; J v by 100J to ?02.0 p3~1 Q A dl'n.:c~ rd compress iu, Lhu sr rin. 10! 1. Ku t i 11Q 63) and the high pressure u i in nzo. 112 IMShe. the piS L01 108 dowrnward and Comproi-wA the r'pr ing 11 0 (non illustratued). Thus, when the. fluw~pE 2 e st a ud 0 UhLi ps:!q' of Pp.~ 6A chang~e to the confioni-ti Q0 M7. 6B, o"A t>Q the piwo 0 atiJ 1 P K1 Wn C no ;L& and th, r% o 100 umni"o0 tvowr,1r 1 ri

'NoN because of the orifice 115 and the action of sping .110, the pistdn .68 is pushed upwa 1rdly W.~ith a vel- ocity determined by the size of the orifice 14, the spring cons~tant of spring 110, and the :rn ot-the oil ini the zones 112, 113. This velocity carn be easily controlled and made equal to any desired v lu an; foli elample, a Velocity such that the p is ton KI2£1 rewtn

to its original upward loca tion~ in about Mol. There fore, after one minuw MaI ar rangevon t as ::Iiit' tie1 con figuration of FiF. 6C. For thn sav rcsA M: the pump is stopped tvc~ action of thc 1 7 (IaU wh *44* '4 orifice 115 will caus~e the pi r.o'. rIn ba.- ck to t., 4* 4 4 rio- originkal cond:U Fi g. 6A 4*

It can bt. s. en, thc rofor Li I I t C'

.5 ntud pump is otartLt i. d rou .w *4444 N 7 the dis tance± d an ;tow.n inV S_ iii 1' the normalI r trac! ed p'oy i t j Pt-' the pump iij stopped t'vuy t ii is added, it follow"* tha! eye f dr~i: 4 20 pipe (usual Iy 30 foot 1un{) 1 '9 v:i

4 44 mnake a singlec dMUM' iI rj

44 its original! UPWar. twn

o 4 44 As wa p)inr(d Ut t'1e. ranged so thot when it in txtc t 0 6A 6,

solenoid armtrt sh :u .f f closes the vctl T''in, Mt n I 4444

6C2, and 6Dj is a valve get s electrical 1 be foarced shur or mec an ca ma f i tO v ti l

Fig. 6 di agr*.'iri inV u -0

In the actu p ceu i n Lhc Io on- 1' F i.

numbers on kt numbVe rs 'on

%11. DIESCRtIPTI0N OF ELECTRONI,1C "FAIL S AF,"' FOR SICNALLING VA1,LVE

The hydrauli-c "auto closC systeum descrii,)d iAn connection with Fig. 6A, 6B, 6C:, and (iii- -;II awu matically close the valve every ti1ia- Lhe arf stopped and restarted, and thus any met-han*c...J s:icking of L~he valve can be remedied Vier(, is ai. hovfver, that requires further attention. II t~ E,~ circuitry 103, ].09 o- Fil, 5A wlrce failI iVV 1rt i-n

a. burned out solenoi c.~Ki dV

would reopen elIec Lr i ca shrv 1ftL)r t.~-I 1 "auto close" dex'icc (;C

Fig. 6E sho-ws itn, el ect rll i nhihb operation of the val-i' 01. v~i- i-n the dot-mholc s~ .a .t

the solenoid Tht.'closc 11 C!

the solenoid t h:r .ns KP c

connected in. sgeri vi tlir.'. no~d~. 104 which actva Lhi t .ht

The resi stor' R 2 is 'n 4.. of the soleLi)ic! driLve 0 solenoid windinl, S,

o'hmic val ue ibout W0) tno tha t the oper. l with respect to Fity. 5A :r t. I.

The "open" el ectric urr, and is shown J iaq, ro., t.r'.

300- the "clos&'e" e'~ I..

a~s 301 in Fi. OF,: iL j~us~300 and 301 .n ~i1~nodwiniings; arld nol ~trs res and R27 POC-mc :4.

V, n1-

S2i2,and i1 1 i2 indicate the currents through the re±-

spe~tive solenoid windings); conseq iently, if 01 C of the vindings S1 or S 2 is burned out w- o)pen cirnuited, no

current will flow and no correspood~ng pulse will W., produced (similarly, any other elcctrical failuie will cause no current to flow through on or both of the re- sistors R1 R2 )A The mnagni tude of the time t yof K6. A an& Mew

length of thv time L has been cx; minci anj definedi

*io previ~ously in this specificat ion K: connection vi

The delay o1 the delo ulew WJ is v~aa tv LNI

In other words, Kochz 302 p-xe an is w-y a pu; se identical VC Ait !njV pulo On v!yv by Timre Av'~e u

Such delay v ;,efs are we.1hw 0 n, Lo' A scr L1,t.:= here. Si-Lt :e dven z' elvrt Y' the pulse shown 1 Ac '~L K->with the Pus l 304 is an aenti -roiucidunz Kr (alv Enw*-n as an OR gn- and prodcos '5 Q W WQ an elvectlc

,s Lgna l only wh-2 unEo 1L L W, 30 isipes on 1 t, Va 11 no0 ht txh~ pul 301 aa, 303 are P-resent W0 ;w a rela oL~tQ0 b3e~the. s ignal 3 on lead Cj5 and i s i vanj;ei to dl ::act v power to the k W 1,-TL a "Cln'" PU1. ispresent (Wi thout thle "01o;o nl 1 open" is (:C00 0 1Js

h~ CCtC system descrdbed in connection 'cith F'ig. 6D. As an alternate arrangerneot in Fig. 6E, the relay aO6 (which of course can be an electronic switch comn- prising transistors) cn be arran cd to iirt. rrupt tL power only to the c'1ircuL for~;he "upeninL solenoid This -would havle certa i n ;idr:nr t agn v aus, I os n circuitry will continue to fuviC qv. nd otv h objectives is; to insure the "clo:,ins' of the. va% Furthermore, an electronic counn r 3:4 m~ay Y1v posed between the ~OR" ci rcv;: and 306 so that a Single EIV.K M"Pini at c:- disconnect the powur. TIKI JW *r w, connected e:n:v after. fe- ux:1, ive Tfalfur lofs.

1>V11. DEWH(.R V~ 01 1 SW(,AL~IIV VAUE

As 'lo> bt 3" Y u

:A i k y at: in, 7.

to ;,rodut 0 !t 1 x' C

AGe an dril i.%

sub tn Wf 1

in hev tip,

the ttI: A e

!eel Ivu! PA operationl of the valve. SA in. 2a c. II A: the t rmc pulse 104b of Fig. .g

0 the vol tagv is sAu( cenl jlizip: PL O C Ar 104 and rises almnost inscan taio"1 shown by numeral 270, rezyiins"tr* for 50 riliisceunKG anti ,tn aW

(again almostV intlivmsy W L! 1A It is very informai vC LU SIQ

valve by rnakin; net !''lu

the solonoi-6 d~ ie windi t nL u (see Fig. 5D)) K1, uch a

*valve can to a A, trJy such a graph> in ti. Lorv current verbsi curr ex~amiple by~) thE a

is it, 'r.

1Ad upon the 'valve stvi- ((a

detetrmnine :n Cc tromagnbrt*

Tit: in Lx to simrpcu vp 1 0

dvitu the cttv a ii ua:P S Ocur1s T'- Wl~ .1n.

is a su: u n t i N

of F'ig. 4B :Qia. VA n: j a

C tfl f i CtwC .1 j Me Vt 1Ca

qu i c;ly cha", Lw was,

Lin val vv o w6 3f a fjt ion. V,6"i

2 A~g~"I Ia. a <a.a.%I:Ia'7 a at-cal current buildup when the valve is noL blocked; in actual working condition (opening or clou inj). The curves 272 for opening or closin?-; are very similar. It seen that curve 272, after the aipic-rion is of the voltage, gradually r ises c thle respect ivc solenoid coil 105, 106 has inducrt~co) until it reaches, in the iaxamp1 e shown, the value of L4 wnlpusa thLe time T. vrhich is 20 nii 1 ThocIi t 4 i>she sudden drop of curren t tha L reaches tht. lo0. val0ue of 2.2 amperes at the tiLme T1 I ich is ?n mi lIi nuconds. After the T1 25 mill i serods, the curirn! a ;ncreasu.'; according to the fa.il i;r "upnn!! anx:'I rcph aSSYMpteCYiaP V, WI Val O~f ~p Ei rim~e of approxima1tely 6 iinJt1(Ip (ch Di- determined by thi resls C.1cc al the 3ol iuia. U wW. v.:hich in the cv V p VA (1'

From a Vudy "f 1h It-N

become appart Ow,' t K-

closing itL the Me 11

tthC MUot 1oC at 1t10 i n.

poLnted out ;'':nnw i 1 W I

occurs durn: "oni 1 1 (1, %live; and 00o C'V':L c

and at the iK T, ?5 i i LI

ndTi I dupurnd a~ a fluw') ofI 1c: cl3

AG different ial prt'.: U Tr~ al mi l1iscererp Ao ain!"- i hi'.

Suffice K :o W K and the current betwqeen the timtes T and 50 milliseconds i'. is in effect "wasted'' since the acutation of the valve has already been complet~ed. This extra tiwe is a "safety factor" to ensure thiaL ceven under -adverse conditions the valve 1?ill aIw bt- cctua! -d when the voltage pulse i, ,upplic-d, In accordance w thi my inveoetion I usc tV si ,nal at the time T1 to turn oftI any furto.r c~r~tto tinIL solenoid 79. Conisequienti y all the current 1 Lv-tecen th-e timae T and0 5 0 mlji I.I conads w .1I b 1 LAS Fuu (!IL ur Ig very 5 ikbs anti al !y thle tontal auc ofl cc'. rL*,JLi3rCal tooperate the valve 40). 'it- c no'ted f'at thcfl 'safety factor' referle Li i;o' is nca~titci re; t int current will coninuc t o L) ri l ci un ci I t vle hu s co-mpleted it-s in; cr 1u c Thec- e I trun i kC A1ci i IV L it -U wherei 1.04 Lnicae IIe V u I tween the powe r dri QL 10 Oln lv i 'I

2a resisLor (k P")oF Lo '15c,:c C' )t rC- r s is tanc e of t-e 1a (1) vol tage Lai s tti1 t oC)T1 aI to cr't f itc k)Ia Kucl 'ai o: wi -ni in 10O4, 1I (U6. a L .S..ar

ne 01CP~r 1C w- Lin j C1~ I' diV CU. I an-] SLU llUd f t '2 iA 0 (r i for sij.Pl t, 1,t. ci t ~u t' a e r L

shown in 5K 271 c.w ctI 1i j- ji ,TK

~c oiitI'U Lice volt~w Cr'. .L t Fi C ni 'l cl. u r t 2 'a

L I I-'1'

%t"-AV

e.u du 2 iv I It2: 't t u'.Ic d V4 1f04. Electric impuloe 104b is applied to polenoid winding 105 (wihis the valve."open" winding) and curve is always positiv~e exccpt during the times be- tty.. T 0 and TV duzing which time the slope (derivative) is. nqgative. On the curve 275 only the impluse*276 Is negAtive. 277 is a conventional. receifier arranged tp pass on ly the pulse,276, as shown on the graph 278. 279 is an electronic del ay circuit (also well known inthe art) which genprates an output: pulse 276b which Js..areplica of the input pulse but delayed by the' time T T~ Thus, the pulse 276b as show,.n ini graph 28 oce~rsplightly later thanthc: flI.'iii;PuIs

276b is applied to an electronic swiLch 281 t hat is -w arranged to cut off the power t~o the power dri ve 104, thus stopping the current_ flow alnioq;t iinmediately after the valve 40 has comple ted ULs operation (opened or 1.1,5 .closed) The eleetron ic switchl 2W 3i s arrangcd to re. store ti-e acti on of powcr dri ve 104 Metcr an app ropriate time. The proc ess rop oats ia wl hop We next. imrpul se 104a (ur 104b) occurs.* It is important to note that rhu s iving in energy that can be achievad by utiiznIip UK of my invention can be very asL aL[. Sin cr vw 1large powers are reqjui red to operate the valvI e 4~0 th the 'V

great s peedc reqjuir e d, t h is s av ug in vor' s i go icant, and A~ couLdc i n the te xamp lu sh own ie: rch !be;ah tter by as m-iuch as 5 tiinies.

Vill. DESCRITI~O,yOF SI ii N SYRiUCTUMj: FOR SPEC;IAL Ti; JVLflY i'(t

An iwp '.nant ch~n crueri I K< the Ml'i rws.1rq'i W4hi. .Drillin (IWI) tg app. aatu1s.noF. Wsjovn'. i n is Practi.- cality; ccnsven I nut and eas; Ql t h j "dipr~ii "t o xLsting &Il well driM Wd .ac o.no~ tow, W. ariIill strings. In the qnv"OLt of th pior art., 1,r,,pr c steel housings 30 01ee or ilorn io a IeiyI I and 8 inchies int diameter *are reqyirjd to house the complicated in- trumentation; VAiMt~~Ir transportation fro octo tQ location requires specially- constructed vehicles. Tn the aprau of thils invention, because there is no valvinyb~echapisrf interposed in the main mud stream, it isipossible to eliminite. the heavy, Ivery long, ex- pensive s'pedial housing (approximately 30 feet long) and only A short section o~f drill collar (called a "sub") is taquirel. In the practical. embodiment of this in- vention, thig sub is: only 3A inches~ long and 6 3/4 inches in diamener (instead of 30 fee t wli ch was. previously 0d reui

Onuie o the important features of this invention, therefore, is that no heavy,*long s;pecial housings are required.- This is advantageous especially when downhole magnetic measurements such as compass iodi natiuns steering the drilling of a deviated hole) are to be made,' which require use of non--magnetic drill collars. Non- magnetic drill col:lars'are not only heavy (2-3 tons) 4112 but also extremely expensive ($20,000. each~) siLnce they must be manufactured of strictly iionma~'ncL c material such as lonel. In the construct ion of the apparatus ofthis invention "'Standard" API Dri 1oGl lars having outside diatneters of 6" t~o 9" (which aro thie most cormmon sizes) are utilized. All of the standard APT collars have an inside diameter of 2-13/16" 1/16" (OP. The simplici ty, small size and coaxial construc tion of the valve system of thiG invention and its askoci aied parts allow a ipeci al fsitire to be accomplished: Al 1 of the pertiLnen-t drivye and associatod coi Vnt canl

be located in a pres sure res istintt tube sffic ient ly small in diameter lo purwi L Wot o be iPWour ed .in o the 150 bore (2-0~3 /116') nf a s .de Wnard APL D1.1 1 Collar Wi thouL utdu 1.y inte 4 ezn W hd N:Iow Son, Sensors *s A5Tuld be placeqd au near Lo tho drill hiL ns u; xoud I be recluircd

-28

1:n particular, a clownhole gamma ray Sensor should be c-ap~ble o~f detecting the penetration of the. bit into a given lithologic formation as soon as such penetration occurs. Furthermore, somec sensors, suclb as a dwnhlecoMpass-inclinometer reu'ieaccuratein deying With respect to the "tool face" used Gf direc-- ional drilling. In addition, a compass-inclinometer must be placed at a Substantial distance from any mag- netic or paramagnetic material. Furthermore, when a comfpass-inlinfome~ter is employcd, the housings 250a and 250b in Fig. 7A must be carefully indexed angularly with respect to the sub 253, which in turn iA indexed With respect to the "Bent Sub" used in directional drilling. lanbThe "'bent sub'' is equipped h an in 1 x log mark 253a and the angle of. LWs indoxhiug mrark mus;t have a constant and inca kred ang ul at rel ationship tu the in- dexcing mark 2 54athait in. placeJ u~i the tel emu .er ing sub 254. This known angle (representing the angle Ae- 20 1: tx-ecu indexing ma rks 25 3a aid 2 50'. i s then iiutruduced :~nto the computot ion fur the cleL:rm'i nit ion oF the buar- ing and angle' with respect Lo a vertical 1)1 ow of th- "Bent Sub''.

Fig. 7A J s a schc'>atVi shuwiua of Mh n~c i al telemetry tool 50 :illust~ratinjg rhQ aryangonvnt wherui n thle ''special, long tool"' isF.li mini: ed and only a short section of drill callar nub :is vccjo lie, an war; previously men t oneci. In MO. 7A, a housin:, gnated by numeral 250 inxmade up of na upper secc on 2 50a and a lower sect i i 24b "n -1 Pin' ma; ci~ lWith reference 'P u i h. Q. The uipcf suctiLon 250. 's

cntained OWNtbi.r a ;.hort tb 254~ (only abo.'c Un inches long) Th is nhOL I sub K ,pc i- ly bo-t d o" lo provid<e nn iniii; dci ameteur (e 4 1 w& wen t. to houso hM vc'u ass ll~y 40 aind a to pi rmi t the

-42-

U u~rstio~dflow A~ drilling mud past uppe~r section tii~4b .passag~.s 61, which are also designated 2 50a is of small by nwortal 61 in Fig; 4A. The housing diarneteT, preferably, 2 11/16" OD or less. A drill, Collar. 255 pr:ovided by the user (the oil company or the dri4Jing- contractor) is usually 30 feeL Ion, and of great weight and cost. The inside diameter of a stanxdard API Drill Collar as was pointed out previously is 2-13/16" -0 1/16". Cerntralizor membeis 256 are provided for lower housing 250b. Thuse are. slithtly smaller in diameter than the ID of Cho stanlard API Drill Collar, for example, 2-3/4" O.D. Small clearance is very important in order to prevent "chatter" when the tool is vibrated during drilling. Discharte passage 85 is the same as that shown in Fig. 4A. Thu housing .%250is suspended within the sub 2 54 by sew~r tv. mean,, not shown. The cross-section shape of 1: whnlizais 256, as indicated in Fig. 7B, is nuth an. to r, ide slots or passages 258 to permit free flow. (Ii111 ng mud U1, The housing 'lower se crion 2501. is notpol .1 l ap.:. of several sub-sections which Mue Lo ai. other, by a special connector meanK n~hown in Fin Tk As shown in Fig. 7C, each. sub-section is plovi.'d cit its upper end slot 260 and at its lower on >cutiion or tooth 261. A protusion 261 of onc snb-..ct ion Patingly engages a slot 260 of the adjkneiit ub-sect Llw. Thkc adj acent su..b- sect ions are retpi no.1 L a conrec,"2 (iuvc

262 which is tnatingly received by the ew( portions Ltie sub-sections. Circular openiiyns P67 in. 0- :*n are aligned with rcspoctivu thionOicd connector s lce\' 262 Ow part. thi av noip by s crew., 265 The specia l ccnnurtu in u;f 3> L

for accurate anu~ iuwan I i I,

A's was* pointed out pireviousl-y, the angle between ind-exing mnarks 253a and 254a must be know,n in order to coimpiut'he angle with respect to vertical of the "Bent SUB1 it is also necessary that the angular displacement and the bewen the axes of a mag-Letome ter- inclinomneter mnark 254a be known and invariable during the drilling' operLatio-n (it is preferred but no0t necessary that the anglIe between. one of the horizontal axes of the magnet- ometex-inclinometer and the indexing mark 254a be zero). For .this pu~rpose the tool 250b is assembled with angular 7 indexing teeth 261 as shown on Fig. C and Fig. 7A. In order to design an efficient telemetering system two requirements will be considered. One of these deals with optimum corditions for obtaining t! e regime of hy- draulic shock waves. The other requirement is concerned with obtaining shock waves of sufficient intensity to override extraneous noise effects.

IX. OPTIMUMI ICONDlU*ONS FOR DETERMlNIN\; THE REGIME Ott. OF HYDRAULIC SHOCK WAVES (DIETERMvI.NATLOi1 OF 2O~PARAMETERS KI (or K2) and T b

I have perfonned a series of experimonL-1 in order to determine the opti.mum cnditions for the regiate of ~hydraulic shockl acs The oceu'rrence of a 1-ydrauliiz shock wa'l-e is analogous to that of the water hammer effect. By suddcn].y stopping the flow in a localized region in the line of flow, we suddenly incwrease pressure in that -region. This initially localized inucase iii pressure propagates i tseli' along t Is 3 inodnl that L~ i he 1line of flo as "w~u I~ha~' '13-0a sudden anLI localized changa (decrease or increase.) ILI velocity 1pc-;Jucus a cor;'vsponlding local izc-d chian,"e (Increase or decrease) in proe surCe,, CThld conversely, a suddin and localize3 change in pressure produces a suddeni 'Iand ,zed lo~i chango in v-e1oetty. Bocause of el'st ici ty andLI Neia of the fluid, the ch~ange is being transmitted fuyther from the voliime element where it originates to naighboring vwlume elements with a velocity which is th'e velocity of propagation of compressional waves. The p-rohlem of propagation. of shock waves is of extreme -c-mleny. To 8atisfy practical requirements, we need to- dpte-mine -a parameter which will be the most represent-aLive from -te standpoint of obta:ning a clearly defined shock wave. Two parameters will 1b' considered which we designate an parameter K 1 and parameter K2 When eithex of these pa-rameters exceeds an appropriate value, a clearly de- fined shock wave is produced. Parameter K1 *04 This parameter is the meao ratec of: c'nan.,t- of thc velocity of mud flow through che byphss valve~ during c4 period of opening (or closing;) of the valve: Let V(t) be the velocity of the mud flow chrough the bypass valve as it variev with time (in cr:'so. or feet/s-ec.). At Llie instant t =0 when the vadlve oeglv *to open, the vi.Lloci ty ib- zero*: i e. V Q. At th.' instant t =T when the valve is fi~l y open, the vel-~ ocity of the valva attains a certai a lue Vt which i., the bypass velocity cluri j the period of full SlEow. us,

V(1M Consequently tho parawauIr KI which S2 ovan r-ij of chan~;e

of the velocity during the period T

KV

iS i r(1s meaured

-32-~

We assumne that when K1 exceeds ant apprupr itu

th-reshold value; when

K> m1 (n)

W.e obtain a clearly defined shock wavc In tin: ex pe iments performed it was deterined that

MI-2 x 05 use Q(1

Parameter K2

This parameter reprc senty K th cean ratc chan-c!

of the area of the openH6~ of Liho valve duinCLg the

period TOv). a We previ ously def in( d (5coe wqv":t i ont Q the area of the valve which i: wphN the L. hb

at t= 0 one has S(O) U in att T nA"

S(T S q, (S a0 whcere S 0 is AL LOLAu~ vpnin e C i iI

K 2 is U 0I Q a

We as suu. that Nqhe-.vn an appop "U .r th~

hold value; ie

!0K 2 /r 2 (t w~.c obtain a clearly cinwai nIvt-~ K Orimern perforrne', it wnls de'Cc ti :1 1Q C

pP rletur K2 in Purh 11 I. q

d ,ectily how to antl aml !hu the I

-46 :i-

There is also a parameter Tbv (see B C inFg 2A) which needs to be considered in the discussion on Fig. BA to 8E. Each of these figures corresponds to

a set of numerical values of K and Tfv) K,A and T~v b I b Fig. 8A to BE show the effect of varyir.t K1I and

T~v or Kad T~)in effecting the trainsitiun from the b K2 n b regime of slow pressure variation to the regime of hy- draulic shock waves. More specifically each of thes~e figures show how the pressure detectedl and the earth's "TO surface (ordinate) varies with tfime, t (abscisisa).

The size of the orifice was 0.5 cmi in th-cse exp(erinients. Experimental data were obtained at a number of. wells. These wells were selected in Oklahoma, West Tog~as, East Texas and in the Netherlands. Moreov'er, some of the *tests were made on an tlcxperimc~ntwl well wacs ex.- plicitly drilled to perform telemet ry X):24.s

In performing the above expe tienLS accuint wj taken of the .great variety of existing wNuc pu, installation and of various interferinj &tFca's. Tne~re are many kinds of mud pumpL: Sin ,1e DUpI L: ible Duplex, Single Triplex, Double Triplex,: and the pulp) Issure variations for a given avera~;e mud ue~~L deal front installation to in~tallition. E. Liuqio of

the large interfering mud pressure signalo is omp1'x. The pump pressure signals from a single Duple, SysLi.: can be 10 or even 20 times larger than those frue. CaLcfUlly adjusted Double Triplex. Foi doe~rmnit ion onthe optimum

values of K, (or K) and of V1 the Orin -wi

Hain was s topped and' a very I'.od A, 1. was used. Thus graphs i n Fig~s >At CLa k pre:suntative qf a typica ondth 4w.~u(tq1 icC a

condition whoru the various noisus (5ita tht qu id other sourcrps) were minimized and Lhen out by calculation and draft ing in o'cdei to obtai opumw values fox the paramters 1(2 (or K1 and T T

K tin CM!Sec)

Fig. .5 2 Fig. 2.5 1 S- Fig. 8.5 Fig. 2-.

a,. Fig. 100 at 4 0 0 a. 9w

Ther graphs of Fig. 8A :o 8E rt; r" -i average nimbers obtained in a large number of n Oese Wi~ts tIL

normal standpipe pressurt was W&3 pressure were in a range oL 10) rv inIC t Wsts i~L were made usin&" vnrinuF ty of :a a mi;A dr.iven,

rotary, poppet, Qt.. Vig, SF is an the standpipe presn urv record. cho! conducted at 9800 feet th r.a" A30. ps i and performed ii on ni' ui driil'*- West Texas. The graph in 5. was witi FiK 81:: acting valve. The num -rical \'.ies j 1C I nc it

parameters in Fig. 8A were K 0. cn 'Sv AnO~T 2 sec; tney w-re similr I U th in the prior art as in FisM; i q~;cil *1y, i~itrzs both Fig. 8A and Fig. 1H reprcsent tMu t K9 pressure pulsatLion on o t 2r .101

obtained usi i a fant a;ctivzr %Oiv r cm 2 /sec aand 1 Q) j0- I Gotv. V j .ilF b r$epr.o. ts I r' "iw and the valve wavek in the valve wavelet in Fig. 2V1

48i3

Ste As previously described and shown in V &A t" O''trfaCL enoodin is

Figs. 8B, 8C, and 8D as ai Ic abo y E. show the tran.uition fror. the r i. s

of pressure La the rgIee In the tests shoun 4 F. conditions were kept a s trumtk~t was 10C a n r I 1 k* 0 a' ,ii

depth of about 8000J feel., 114 v

and the wei j-' VC Funnel, when "opeii" hat* ar. eflet v :t Th~ ,0 normnal stancipipc es-.rL.* ~L 2~.ed in these tests wi.> to permit. slower W the va ive L .U

anLd the f lov ra±t e the inlet paiss 'S

action whichl c'' but it did not ro shock wavces faster act ion :1S (If of the ordc-- By Li. i* restriction sol-enoi ds, It

4P' produced xw.hcx. wa ve is prodi,,

OBTA I~ i t t

Q, .TI 'i

One ofl t hi 1 il I

-4

11- i e 1,1 it thri 1 1 4 "l)(11 it'.

-th' amount of mud (measured iit.m or in o)which

passed through the valve during; Chot pci iod (Trhis -quantity is known as fluencA The w~wr ._.uioi'ch 0is based on a parameter K 4 which repre~ ont th nyj;

fux of the -mud st rt a& dturl- 0o: ptr> I

amotun: it pase i n T (V) 'KIL T(17)

*Consider e~of the perio oin4 or tht \Ivci.

Me period T oSMM K ra!M" :UUM a the rate of increase 0t A 'n f 1. .w Ku. C period con COT

SO t i

Consequently t; v, w

1during !.ht t iir T

ttrough tka vaUx( J4. fvI 2'

;ouni. ol H,Iu iCcv wi a.nd clor-iqc of t% Vo z Ai ak~n j- 11 the flux for the period T Q)

K K3 2) K4 Tv=

XI. GEN[ERAL. PROCEDUP. 1WG rnOIn ULMX.''

Considpr now ecne ral pr ni,

signals from the pr v; sure I aL oc)A :o

the appara t'is arrci:. e*nt-n C! tratle certa in ujvt no: an n.2 uhL

in the decodi: of sign"!. ans ofthe* r

of Fig, ThL' i nal oh. :s 51 coprize a tip-'ful1

o'r ma~sk the u s, 1~9

arrying He~r. repru bs. by mvncrn~ of va 1 ve art vavlox. ur Lr~n

K' 'KUKY

iOp and b~ack zY "n 99.

andi LWall Oif th bur( Sl .9.

xl

Kx (9rdvr t 9 t 'I

t

I kh1 o olt W 9.v

In the terminology applied Lo this specification, a distinction will be made between the term "filter" vL; applied to the frequency selective filter 1 50 and the term "digital filter" to be used later in the description of my invention. In a ''filIter"' such as the filter 150, conventional fil1 tri nt is performed by moans of analog~- type electronic networks, whose hchavior is ordinarily treated in the frequency domain. Tic term "filter" may be used to designate what i s known to hie a ''wave fil1ter"' a ''Shea filter'' (see for ins;t ance, ''Transnmiss i o: Networks Sand Wave Filters'' by T E Qua~, D. VanNos I.rand Co. Netv S: York, N~.Y 1929) and other filt ers nucil as Tc'hubynhev and Butterworthi tiltCr,;. On the otnor hand a digital 0 fil ter such as a mar ched il1tem, a p"Ils shiir' filtcr I- or a spiking filIter U ma)rt~ fraitf ul lx I re it in riV X' domain. The output of a di it 1 fi Mo is -)It nt J by convoivinerh l 1~i tal I apo uacw withi the weighting en <M.c3ent;.i A ij; t iI Lt~ is CuLYIALCr The sig'nal1 rod~ed at the outj'i. e vs a 14 of 2 the f ilter 1 %fm Ail 1, a a1a

-~whi ch1 is

wherc B3(t) is AtK USIA.1 P t s t Pc. 1ln c r L an r 1 pressule u\';1ra ta i cv-,-tK ,US L h t I V Pur u represents roclois Ou'.o T.Im by varioxa- winy such t~. Qn ih, oniA

cut i,~1 t1gbt oa V t

0 1 n,

0 inn. aIM L

other cusebi 02 depazt'ure pit ,he suhsL004J'

The coded n s sa 7 e expr cev, od by t Owi omi o carrying s igrial B is o s w:i-is of ii nary w~orcis and each o E thjesu nLr words c on ft.nx a ,;uc o,AS hion of Lb Ls .A s i ng 1 bi t inI aI Li M!I -'co WO 1 isSjd7(nCtIC' b1)y a single "opernt c (i a) si I~n1 I eopcndin na(1 Closing) o-)f t hy Va, iv Sct) QII C, r a 1o 0 1' C 1 r1-a s ai hydraulic shuck w l oh x1i t-s 1 .F at- LI, L>OL sur fa ce o f rhi e eaI I~r ugl wVk1Ci 'rnlvi i n as the valvye wa vi.1t L in F 1 21 1 C;Su he I message Le0 CIth-y cr~o it lria c.ojJ sequence (i''jV Vv. e0

being of the typv ho'vnit, I Fl L 2 Bij. 0! to lG show variLn;5120 0 0 ConIirhOincide t

s ep aratLe tie L11f ri 17rr 1:1 onn o i, I -n t lie.'n 11

ion-, I haiv c rj JL. 1 lvt

of V:L.I\'c aIi C OA of ticf sc-r'a' I ;i.1 I i n I

2B T h us iI Ii i fC.I

ICo'ignla t d..sp

SC-ript VaI I-i 1. -t i 111 iuii heei, appro''i Lat C 1 i J> t'

inteest 4 'i a ,JK LiA.711e a C I1 1

T 1, 0, 1

.strinlgs. Ii the a tteHpyt :;of tmp~ ruL L~ pc stee hos ings30 ee Ior tor a on 'Ind -I Lie i.rI

1, Q.-

Step 1: In this step a signal- having three corn ponents ag s hown in Fi-g. IOA is transformed into a signal. having t:wo components as shown iin Ficg. 10C. TEle purpose of this step is to eliminato~ the pumnp noist As a result of this step) a vlewavelet" ofti Lype shown i Fig 1OisransFore iLno a ''double laet.".

Such a double wavelet is shown in Fi,. Stp2 The. purpose of t.his st-ep is to eliminate the random n-oiseo nl 3: In this step e".ch dIOUb LU a et as shown 0*in Fig. 10D~ i s transforruca into a sim.le pulse as shown

in Fig, 10G. Coris ect-ucen L Ly one aot a,-iris a ecded sequence of single plses represening 1indigital furi.SLt the .0:00: parameter measured by tiuc senzcur 10' aLtC nY-1 o ate o**125 depth in te b6rehole.

XII I;L 1MINATlOl OF P UIW? NO I1-1

0014, Cons ide r rnow Fig. I1OA. T! s io thIe t hre e 0 *0

0 00 co-mponients of the si iua] FP(t) eu io (22) c r heu Va 't v i. t, tI f 1) pU11 no10 1.SeC '0 P and t.I- rn d i- i no ii U \Fs 1n mvi(), Ly poi n ted out the s ig.gc. t h as 1)(22e1 oh ai 0 nI b te1 filter 150. This MiL-f is c(:lnec.i-ed -c a d~lyelement J.52 which i~s ef'c.LiVt inl d. .J'i e i SLI goal F L) by an amou-nt T1whr T i ('iN 1pmriad in oscil1latLion

produced by the pat. 271. T1. tc w iotatndo I the output lelil 1 of the I')eli' c(J be EQX-

Prevsed 1 ats h- r.i..mr L t are 2 1 dle aycd va'I ye waVod b H 'I Cho delayed pumpj na- ;i P(t-T) p (1 aInd the (dclaytul ratujom -noise 11w). i I J:-c .intel va T deends on hie ;p ccdl of r(Ato ion oJ t hL- puImm'p ind

C

'si~uce the speed of, the pump is not constant, the delay T. is a variable delay. Thus, an appropriate control for

the delay element 152 must be provided in response to the speed of rotation of tlhe. pump 27. A~ccordingly the delay A1M nt 152 is arraniged to receive through the lead 154. timing impulses obtained from a pulse generator 115, which is mechanically driven by the pump to produce an *appropriate number of pulses per revolution of the pump. A chaini drive transmission 156 is provided for this J* To .Put purpose. The delay element 152 may be Reticon Model 0 SAD-1024 Dual Analog Delay Line as marketed by Reticon a Corporation, Sunnyvale, California, U.S.A. Assume that the pump 2.7 produces N1 s tro kes per

second. Thus, T~ 11N. The pulse generat or 155 pro- duces timing pulses al P relatively high rate N 2 which

is a mul tiple of NI- Thus N2. KNY where K is a constant.

0 A 0 which has been chosen to he 502. Thus if the strokes of the pump are one per second, tlis would reqjuire the a signal genera tor to produce 512 pul ses per second. It is apparent that' Chu rate o~f pul sat ion of Che mud pump 27 varies with time and, accordingly, N2 Ki11i

vary so an. to inv.ure that the detlay produccd by delay olement 152 will always be equal to one period of the mud pressure oscillation:; produced by the mnud pump 27. The signal F(t T derived f;oin the delay el~ement p 152 is applied to an input leau 153 of a subtractor 160. The subtracter 160 aflo receives at its~ input 1cad 161 the signal V ler ivcd from the filiter l!50, ani it pro~duc es at Kts Ou tpUL 'kcad [16) a diiif*CLL 1 Od i which is X(t) hit) F'(t-T)

P p

ni: I

Since P(Q) is periodic and has a period T P,4 one has

P(t) P (L4) p

Thus,"because of the periodicLy of pulsations produced by the mud puvmp 27, the noise duc to the pU.'j) has been eliminated and the signal obtained at the O:::pUt lead 162 of the subt roe[or 160 can now he exprosncd as x(t) Wv) where B(L) B(t Tp') (26)

is the informa tion a ry i n s it nl and(

U(t) U( Tj 4

is a ranicdom noise signal. Both tie iQifor"n:. Lion carrying signl. 1 and the noise signal u(t) arn siw: in i. LOG. It ein now be seen that by performing the step Nc, 1 as outi ned abno I have trans formed the in fovr..i t ion ;arry ingt' tinal H as stown in Fig. IDA and havinig the f man of a v'alve wavelet into a different inforii unI. urryi -ignoal b(t) as shown :n Fi. IOC. lhe sinal b(t) MI be referred to as a "double wavelet" inrCOntr to the signal P(t) which represents vlvl wavel A diou-- ble wavelet comprises two valve wavele s su(:1 s the valve wavelts "A"nd ''an in' Fig. lOC. TisLe valvye wavelet s arev epa rated one from the o ther by a time interval 'I The valve wavel et is siW.017 tu that.

o Fi. I.AO whereas the valve wavel et rc 'rosents the irnvcrted foni ol the va lvc iavelet: "A' The signal x(t) (6quation is fur uppJiud to the input. Iead :62 of an anal og to ci gito I (A/D) convertr 163 which ih co t'ro lied y a clU P8, (i 01b ta ins at the output lan d 164 of the AID converor a signal expresed ath (28)i where in accordance with the symbolism used hero btand utare digital versions of thn ana1nt iqna Is x(t) Kjt) and u(t) respectively. The sjAl an,!n

Ut ~r nthe form of Limel

2

and UA U1 U 0, U

respectively, and the signal 01 1, l11z Cae I

b- b= b, b", I 1h) tn*0

XIII. ELIMINATION Of WV C NOISE IS \1 iNHI. KE Nu.

The mixtule of a doublu 1

a ,.va ft nap, ci signal u tis. now~ applied .o WH 4 P~ a a- 'ft a a-a filter 170 havinr' u Piuouc,

at= (not a 1 I2' I a .a

I select in LhiS eiib~dOciM~ I &a Kit I

a-. matched filter, and I choose iho nemon!"k-

optimize the dperat ion of the Ulitur i are achieved whvn the signal to nol -P rd .I

of the filter 170 is at its maxiimum va.lue. cription of matched filters, sac foy inst :u LQ. cation by Sven Trel t el and E .A 1ib.hm t 1. Digital Filers fi Signa 1-r 104 RNi K GeophysiLcal PraspucLinrg Vol I 7, No. ,19C 24;8 293, 1 publication by R.A. JIKKio M 'Go nm'cat jut and Oewc lLn w irh S3pucia Rt ~I~d~1 i~t Proces~sing of? Rad' ii- and :ist! Si gnt A~is" 1clVFnr* Putb lLirng (;(oqpnnyN York, N.Y, 9067~

An 1 1A

I arranoge the memory function a~ of the matched

f ilter 170,to be controllable so as to insure at all times during the mneasuring operations the optimum con- ditiefia in the operation of the filter. The control of the fZilter is cffected by means of a computer 172 A which re-.eves appropriate data from a storage and re- call element 173 in a manner to be described later. A signal y obtained at the output lead 174 of

the matched filter 170 cani be expressed as a convolu- too. tion of the input function, and the me-mory function 2'a Thus, t

ytX 3 a xt- 1 a x (33) t 0=a1nx- where the asterisk indicates a convolution. Substituting in xt b 4- u t one obtLains

c t (34)

where

c C b a

is the filter response to Li pure sigjnal Lilput and

Vt.a v(36) =U t is the noise output. A scherati: block diagr.am indicating these relationships is shown Fig. 11. In ordek to insure the optLitmm conditions in the operation of the matched f-'Ater 170, a Certain time, say time t =t0is chosen and it is required that the intnaeu oe ntefilter output containing a signal at time t t be as large as'possible relative Lo the avc raga power in tile filtvlcec noisc, at this in- s,.ant. Henve, ini o-rd(r to dletcc t 1-he s igni c L~ in the filt cc ccc out-put ut, us.. is of L.he s ig!LIi t -nouise ratio defined aG

(Valoe of filtered sional at tihIwe t0 37) Power of filt ed noi t,

If one convolves the (n 1) 1engCh signal (b 0 bY bn wi the (n 1) length S ilItr, one obltAins a

(2h 1) length ouLput series C I

C2n-l' C2n) where cn is Lhe centrai value of this out put series. Thus, at time t hI bcumes

9 *09 n b n I~ o h Hi= 38', TEI

where Ev' is tu avhee;. J u ou~tjai I[

power.

V V.

i

1 d r-

-4Li6-

I assume here that the randow noise u is white noise. can be shown (see for inqtance a pub- Then it iC0atio by Sven Treitel and E.A. Robinson timumn Digital Filters for Signal Lu Noise Ratio E:hancement". Geoph. Prosp Vol. X\TI, 1969, pp. 24i0-2943) that the ma:Ltnmur value of the signal to noise rat cmi

be obtained when (a 0 all a 11 (khn ky (P9) where k has been chosen to bo on". of a signal iimrters('d in. %-:1i 44* the optimum condit:ions cvoi 1 bt

*r 4 of the filter is jivon 5 A, i nv, 101;, namely,

by the coefFicient seqiinwe 0 I i

The nmemloro\ r th K" AA at aLl K: 15 times by mvann W be C'MM": I ice i n:ec' ('U

ail W% to the fil ter bv h c *iiw used hereinri ref erF to s"i e ('7 F o"P. .2t or transmission mean.-., na iL La

A storage and recall lo w A

the function b L fo a W through chanonu W ti t7( L "e M -1;I at 01 *i I of the coputer is LO i 'vert 1h,~

by a ."uqiueC (h 0' b output channe 1 1 75 a .nec-reca (b 25 in turn is appiivd to I channel 175 and st oi'i th-r :P in in accordacic' w h Qw heqt Y The fitrc oulput y t cii' itO It..

174 of the mnnhed filo l- K li'

digital to .najon' cUOvL; wr a signal in dJ!i r aii A v.

f uncri on oh a Wad ni I h. 1w

1' convortar 181 will be expressed in accordance with the symbolism \tsed here as y(t) It should be noted that maximizing the signal to noise ratio in the filtered output v is equivalent to minimizing the noise signal vL (or its anaug equivalent when compared to the information carrying signal Ct (or its analog equivalent Thus, v(t) c(t) and a0 ir)Y (t tbt Therefore the output function of ti matchvoi filter as shown in Fl. IOD closely resemlsc~.; the fun- ction b(t) shown in Yi. An important of n' inwp:;l ion in\uvo storm (for a suhsequen t reprnduwi.) the inci h Mun.

of the ntorage and recall cement 1N. ruqairu procedure for storin g h Liill now e cexp i: coi!- t nection. with Igi 2.j Thu It'ri ovdu' CUll: .t 0

cral steps :s follor;s.

2U 1r Drl w i.! the bit 31 1, !ftud a nurt itanL, bt the draw wo:h_ arc :maivt in1 niti101 ry, ano h iotary 21 is st..yp'd fro: t urn Lu6. StQp Par 2/ cant :naa:. i ar.v Jun ig normal driirt i proceduroq, .v ":'rrn pump rate and a puwq pruurv reui of mt ralUSK during; the avr ua "menasuc-tmin ts Kb i dilli ng" Al otther sour, of inetrcrfurv n, as A. C. ele ctr i pick-up frcwi ;,cnc 'rtors, upri li u, cra"P, etc. F

Hiinnated' iuma;Fr an- pc. oiv i n. ca. v rih (as by sPlectW n c-al ay)

'A

a "3, 1 I"

Step As previously described and shown in connection with Fig. 5A, the subsurface encodinV is determined by a "clock" which is in rigorouj syncbron- ismn with the "clock" at the sotfa cc equipnient Consce- qu en tly it is possible at the sarface to make a± detcr- -nation of when a single pulse is genurat& at he ubsurface,-for example the precursor pul st, and b- knowing the velociry of t ransmi ssjun th1rou~;h the mud column also~ to know~ the~ exact iis. n whi ch Ke y-

!veand tv vuvwP in adv ,uce \.hon U i. u 1..vL vaiv

appears, evn thout'h it u"Id W. cd -y vn.

is pract i,.Mc. !bus in yr~ai an

at a known via

n.E

1 HUI.

as out i no~d in; t 2 (t s 1w; .i b1, a:J con., a: Mh ow p.t If KI lI U

OW NO.

1 50 is pas~cda i t L~ dK C which AW Wo

and A/D cw ,rer W" j. oxplaineci 'yem. C. Aa 11.K th~e s ignl Wt t tI pi is of ti'- i IK

-u O- !0 dri ll

-62.- 4 <1 again, because the dr i 11v~*. Tevii ped the raindomn noi: c s iyna' these conditions urnc Vy~ n as nearly as prc[!> hlw 1 would correspond. v. v*;to o n :0 ar o carrying signail. Step Thic fanc:

The opvra: i.I: it

as out! in 1 .1j

operational arr2J2 '.2

arrangementA Li' t a NI)8

applied ro thn o' 1"'3 for ru. u' X,

rnem.cry turic expressed nf

v':he i fr1er *r

Of the' +'0LPif

white can, in sorv of an IUtcO~orrela., I.

filter, such do this thu fied by climMAi. 172, anid F- or b,2% ant ocorrelIat or au 8, 0CVU W-

-AT I.I LI L

.4

the output leads of the autocorr Utior won d be connected to the input leads 174A of tho DO c~nverre 18J. The output of the D/A convertoi.r njy WA process Iby means

of the delay e2 cnur 190, pulrvt nnv'. A.) AND gate 193, etc as shown it fi It wt~yy'in S;OrCTC instances the ourpu~vt of the2 N/A con I A. I

directly to a reck rJier.

X1V. ION 0" i0' T~ i

~PULSE NG. n a

j A.

of t [W, An .df L "A cun'.A:LAt r S rt St

Kt) which iY- 11. h- 151I l~r a toC) t tV- oi

vVL .1

vc it~ is app" rc wt A)

(I"

valv 40 i Li u t~A!Ipd.vL .1 C. A. It t

Y! upNn 3 o" zwr IM

Ynort p .12 2 1duni~ noli K he (Iv

f. .4 COMYi !AA 101 l\ !V A.

It 19:)

dl C laen M .L l A& "V a WOO Vt

I iL .s 1 ,r i l I "d cI A Al

U

at the output lead 195 z, dl ay eqiuna :t (2 -Val

TT .The delayoci funccion 'I 1) u,)

I OE is fur the r appIi ed t hvin 11 WXo c, reversal e lemnent 1 i2 to ~rd~ en t of the eleMVTnt 19? an1 i -VL-rt IU aVt' expressed as; -1 t T r) m1 PIx'ni

The siglnal ->(iL TIII 1yI1 -c 1lead

197 to the ;V 9- 1( r) cer iv~K~~ K Eat

Lhrough tbh. cU-,: C)f th e i w! s15 I- D Q

have POSi t i.u In ~r ina I b(ii

nF i~ ;nu1 se in F 4

t- t

L~

hu in f4

u; h11en II t 111(

-)v1 ini I,

1 ;l t

0l t, 1& I i 11

IN a single opening and cas i no A 1 A 1 1 W keep in mi nd tha t in ww! r 1 thi ou 51'A measuring ope~rat in one oban d WE IC a coded successioun of V 5;irgL' measurement porfo~rt K A c parameter. It (I The cnditd st Lu ,i ~I 'I. the output ~leadPn lCcA a D/A conke rtai A: 1 0C Al! t ht out pci! mc- t L. I L$ noi se cilii Tj

Co)nvolIut in

12 at i oil (i!

iS t hC V, V.

S*t An. v.

Py 'ti it i~S 1C n'!

CI" it; vi, asltOU aqp ostB Inq (C1. UOux', lS?) 4 sl

32 2 2

1L2

MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAUOF STANDARDS-1963-A

.4~4 4

.w s piovicded with.Lwo input terminals ZU.I ancd zuz and an' -output terminal 203. The signial x derived fromthe A/D converter 163 is app:lied to t he input terminal. 201. whereas the s igi-al. bderived from the storage t S and -recall element 173 is to the .itnput t errriinal 202.. A signal -representing the- cross correhation of x~ and. is thus obtrained at th'p_ output I ad 203.

is easily seep tiiuAt the cross correlation signal obtained au thr output lea.rd 203 is identiczal Lu) the- covouto ,ral. as expresscld by edluation (33)

and produced in Fig. 9 by the ma,.tched filtei. 170. The ~'cross correlaion signalZ1 IS futher processed as shown in Fig. 13 in the s.-iie mnan-ner as the sigrnal. obtained by means of the matdChed filter 170 was processed in thr- arr~.g -iet of Fig. 9.The cr_oss correlatoi 200 may beofthe tvpu known a s Mod.e 372 1A as; -nanriFac-tured by lowlett Packardl Companiy of Pa:lo Altfo Cdii.i Eorni.

XVI .E..LMTNA" 1P RLDOK ION OF RAND)OM NOT SE WIIEE NOTSF IS 1110 WRT NOISE

i When ra ndloi noise Whi tuc!IoI( s e thut aij cor- relation of the no~i se function is zo(ro for tJ0..

Cons ider Aic, c;as he the unwd.L tnted S uu hs Il

ai known auto( co rrela ti n functlo, Cac~we ho co-

efficients qarc, noL necessaril y zer o f o Y. t 0

c nn i'a dis rt ot on to loire wI e* rol e, 'Jnf i on shin co van anie ~lv uneff:ic iunltis An app ro- oriate forn: o 1 Si-nd !1 Vi 1 Itcii icc)( .1 ct

'howr~'l .C1 o V.n s th c n~ t L, 1. *l Lo

677

sp iki ng filter is ai particular case of a Wiener type pulse shaping filter in Which the desi red shape is st o fl :0-1y1 onb thle inf ouncmt on -carrying signal1 bt

(sbY means the e Iem e-n L 173) but'tlso the noise s Cgnal 11. A9bqrdillgly, the arrangement of.Fig. 14 'inCI,-lde two Sto0g a,,e an 6 recall elements -which are 173 -iid 24.Tbe storage- an,d recall element 173 performs a. L Linc ti on wh ich1- is identical to that of the element diesign ated by the same numeral 'in Figs. 9.and, 12. It serveLs to tore and slbsequently to generate the fun- ctLion bt OnY. the other -hand the function of the stora:ge and recall :element 224 is to store and subseqjuently Th-prodcie the- noise f unc-tion u. The data representing the f~uncLtiuns. -b and u obtained fromf storage elements tt 1.73 and .22. espectively, are applied through channels 22 a and. .226, respectively', to a computer 223. The fucti on of the computer 228 is to transformn the inpu.: received fromn the&input channels.-225 andi 226 into dlata. 'r ecqired 'to determine the memory function of the matched

f iltert 220. The latter data are applied to the matched filter 220 tir~g thea. channel 2.30. The notation will be the seie as before, except, that one must now bea-L inj mind that the nois.:! uis no0 longer white noise, The matched filters to be~ discussed here are indeterminate in the ;;ense of an 'I arbitrary mplification factor k, which is setE equal to unity for convenience. The same definition of the signal 'to noise ratio pi will be used. Thus

I,; i '(43)

B is desitred to 1lxaxiiiwiz2j SU~beCL LO LLIQ assutacp- a -1~tatL th :inpu t rI-IG i'sa uL s of the auto correlated k~m Tt b coveLentLto introduce matrix nota- tion at, thi S poifit. Let a= (a 0 a) (44) de! n~~t the (n 1) row vector which characterie ~temeirory of thie matched filter 220. Furthermore, let b bn; n be .the (n row vector that defines the time reverse of the signal b t and lot q= be he by (n 1) auto correlation matrix of the noise. Then one can write

_(ab t (46) aqa' where the prime C)denotes the matrix transpose. i* V 0 SOIn order to lna~diie pj the quantity (46) will be differentiated with respect to the filter vector a and the r-esult will be .set a~s equal to zero. A reltioiiship is obtained qa' b (47) which can be written out in the fo-rm

a.1'

1. 4(8)

I.

I ead of thc D/A converter 308, one obtains in, analog

This is the "Matrix formulation of a set o f (n I) linear~ simultaneous equaitions in the (n 1) unknoin

f~ilter coefficients (a0 all I I I'aou-o yields the desircd optimum matched f itr in the pre- sence of auto correlated noise_. The eqw-it ion (48) may be solved by the Wiener-Levilso- :cursion technique (See N. Levinson "The Wliener al-. rror criterion in Filter Design and Prediction," Jour of 14,at. and Phys. 1947, v. 25, mP. 261-278 a!-d S. T.reitel and E.A. obnon, "Seismdic Wave PrOpag'dt ion in Terms of Conun- icatio-n Theo)ry", Geophysics, 1966, Vol. 31, pp. L7-3Z) Thi reursive method is very efficlient nd stus -t

possible to calculate fnitched f i1' t r o i Ereat length by means of the computc- 228. V~ imitisi this calculation are h ot c;ea>fl ati 4' q and the time~ reverse tfhe .&Wtt 1 while

the unknowi u 14 .n Lcrt1tio Olt-. txI r erciuns a

These filte-r coefficienu s nuctio' fu:m*:~.vI of the ilter 22-0. C~ic~ The co~p a osw I "~ud emn

the memory functi.on of i-z, d i t 220O are per- *formed by the computezr 1 ,i co--np ii receives froll the storage and rocal' L i t s: 17 '3 a :d,'24 Cl regard i n{ the functions 1 and u c~t i v~iv Coo-ti recept ioc-.

-Of qtthe noi qtu- auto cor..a tlat a'itd

and upon the reCtOpt ion f 1) t1w 1itr, versc of this

signal i s dcterminud,.8Iau Vu~e.fle

coecfficient,!, ct are ae 'i .:ed

throupgh the wutput cla.A 2 30 to t filter 220. The ou't ;w of t LkO- li tC. a D/Acon-vertor 18 1 Lld turth, lluLt-, 0~ i Lhe*. (1 samue iuianuir as the out put of t he ihU che-Id MAi -cr 1 prcsr In the a rn.. i H. 9.

In frequency domain, the memry:fu~nction of the man'hed filter 220 can 'be cxpro'ssuid as AM e-2 iifn B*(if) (49)

v~hera is the Fourier- trans form of the time reverse of Ch'e sigbi& b =(60 1 h and Qv. inthe power

spectrum of the noise in the interval. (f 0i The cart physical meanihg of the exprc's;ion (491 is si:>ple. The larger Lthe amplitudJe npcctrm B f) o sign,: and the smaller Ac power densit et c-r, of thL pe S p0 J110 noi:;e in the interval Wf "3if), vh t adh nt filtat transmits freqcuenc.'ies in thzitThus, 4444 4 -4 4 if the power speCrral OMMAItv 01 Au 004V i S Sri~ I1 .4

.44 4 44 in some interval ofA t ruj2: d i t ht 4 44

4

4

(attenuate~s vcry I AM) in K::V 4 4441

Considier now Acusign :va, a rW!Kuew 4 *4 ~4 4 4444

173 and 224. The eroediu e- 2, b t by meaRvi of t he ee~mot :17,h 4 I-7

8 scribed in 'e 4 444-4 4 4 4 by means ofrhoW'4'''u2. 44

4* A cifli rvnt prd i "I I 44 4 4. 4

the noise -inal v V 4 44 4* 4 pointed out' pre,'Lwk$lQ i is poss;i~b' p trp rc~ wd L- 04' 25 Simillarly, boona. K. hv ova,"i 4 4 ssutrface' and ur- -I 44*4

receive a.nd1 b> tv "js't' l'v, j Ad a. I

1"Ia! Op, 10V t,'~1

a'

-71-

J.G. Claerbout and E.A. Robinson on "The Error in Least rto a Squares Invarse Filtering", Geophysics, Vol. 29, 1964 o pi'

S

use to i II s use to thIie required procedures. -~rate The S t e ps ~f o r obtaiing a record of the functioil u(t) can be statad as foj2Ao.is: S Le-p (at) W~eigbtt on the bit applied and normal -drillirg operaijions are conducted. ~Stepj Lte is chosen when no infoermation ca-rxyi-g s.ignCral is presenz; a pause between 'sords. jbi-nary. Step A signal is obtaina which represents pressure variation uf the drilling 1.ui' at the trans-

4,4*

s 4

4t

U:4

4

4 4-4 *r

4

44 p

4E 4' or 51- hissignal is transmitted through the filter 15O0. Because. o.E.Uhe timne cho'sen in step above, thba t c the stgal bW0-- is nonexistent, and consequc-ntly, the hand signa'Lqob -ained from rhe output of the filter 150 has 5 shapi sense Stp Pump noises signal P(L) is eliminated1. This 's accomplished by means of the delay elemnent and si btcxaccor 160. Then zhe reSultant signal is ap-- see, plied to the AID converter 163, Since i,forptatiwr- 10 and S- .1L0 carryinig signal is present, b 0, and :~n~etl' Filta 4 *44 44' the signal obtained from the outpit; of~A;i 333 o 4 conivel-ter 1631 has the form xt =U t, 4 onT S(-ep recor ',of the f::i~ 4 4,E 1o ob~Lti\.Led by iutilizingtr toae 44,

4 224'at the outpDutOf Lthe AID zon,.er er 4 4

444~ 4 4* *4 4 via 1i *4 *,4

Svumiarizirig wh11,at has been saii. a ,,,nb seen -that if the~ noise is white, 0-tI. 04--e ~f pul st

170 and related crpnv.~ai'.~i Zn havir 4 12 2b th-e optimu*;. ,value of si 4 -nal tL n 4 44,44

44,4W 4

noise is riot white but. has a Ihown r2' 44 4 4, 4

function, then thc matclu,,J fi ter ,.Qc~ *4 pon en ts as s hA wn in F ig. i 4 ;r1 4 4 4

value of

-425 XVII. 44 4444 4

FT,. 15 s~portion ah of'h e~2 )il comprsl-,- l 81cev t or

isdifr F- o-atht,

Of iim. On Lhe- other hand, the case E -1I correspund. Largc to the vorst possible case, that is, th-2re is no agreet-* and I or j--n Fig. 14. The inatdhed filt r iw~g 9 or Fig. liS optij.muii i~n the sense that it is a linear filter tiat opfimizes V)ke signal to noifse ratio. On the other hand Aje filter 240 in Fig. 15, de.;ignated, a pulse S shaping ifilter or I.ener fii pr, is opti-tum in the sense that it is a linaear filter that mnimiizes, the mieaz, sail-are differen~ce between a desired output and ani act iaJ. Qurput. (F'or a description of Uch a filter see, fir instance, the publication by E.A, Rohi-nson and Svea Trei ccl on "Principles Digital. ncz

3.33 or a -publication by Sven Tr.-iftel aW i A- %oinson on, "The Design of High-Re sluti: D401 a i Er s IEEE Trans actillons on Geosc.1ic- 7'.1 Vt rni. Vol. G;E-

~The pt: Is e sap i c' via its inpur channel da-va %,A

bt pulse shaiJng filtn iAs an hvn e.r

(n 1 ei~ 9 t

n 2 ~t~

A m~odel for f n~elel there~ arc

The output sign~al zL is a convoiution of the filter

memuory funcuiona :C wih reTput function xti that is, =4 z4 (51) t t

The problem is to deterin "~he movory runevion F

so that the actual output z is as close as possible kin output bt. the least error anorgy sense) vo the desired quantity To select tie nemio:: ftmction thc- foll owinF~ is Minimized: i" ''Soo of squared vrrx4 honve desired Ounw u Wn. filtur vicnd nvelc*) f (Pver of the

wh i~s v TAOS;n cd wCI &Zr rantr. a- ired~ No A! zing TEhe

245 nhrough che chanval -A &zoa retrOng the~ function, Y OraT S b Siwilar!v gvrm :tn aA

0Y w n 4h 4u co y; 4n l 44t4-!

;.Ar WCU1 t .cnyut; 44.: 4 rrav;N !o

Wt!- 4 t4 h, 10 In1r Mon A 44

Kxer A z4.he4 W4061M

I 4 A 0 444r 4h II

F I <44.4 4'

4

!east ero en-ysnea ls: svOUIet h desre OUL'"-b te od

zt bt 1 52)

as Shown in Figu. 1X1)

?10~. Symabols: aIre patriaeMd by 7means cdf thc cIXI.-Le: the quantit y I to be rnil;1i i UI" is

4; '4

.44% 4 4 *44. 4q 4 where the r~ Li 4, az~d where 4*44*4 4 4 4 4 #4.44*44 4. -'4 4. *4 44 4 *4*4 IS 4 represents tht jj' .~rj~ 4

for K cz-~ ,Vt 44 4 'r N 4 4\

N> t) I' 44 4 44 C ~2 44 4 4

He ri A

4 CtU

~2r ~orreiatior r itf 4 4 :2 4 .4 4 44 4 L~ 4,444 4 54 44 (A 4*411 4 4! 4 4.44(' 4,444

A 44,4444~ 4 114 '4 ~44

pulises laisting svrl ilscns)art' transmittecd,

-(56) v S t-s L S=

for t 1, 2, m. In the above equations the quant- ities r qts and t are known, whereas the quantities

f 'aro unknow.n. compuLe1 245 serve to Calculations performed by the qts and gt fruon the in- deteartine the paraeters rt-s' 2Q8, 241, and 246 put functiLos applied to channels rh equationS (56) for respectively, and then to solve Th:!i! vt. t-s qalteS the unknown qiantitieS f S and gt are defined a.; is the autc input theeati(; The paraUC r 245 hrugh r sigal which is applied to the c01p.eY is *ahte s correla- co tlhe charixte 2-ih. The

iignal u which is vl applitr :o the tion of tht noisc 0-vit- thc -~nnl 247. The pararireteS 1. compiuter 241 t1.

hi crx)s r-oeffici 'r-Jw rew between art jitd dt

tht desi red v bt1 aiv 1 n x Thus,

(57) x

vT-> U±he i'oif the f or t '415 through de ed n; t~s ti apl-; tni Lputer

i -ti' h e-hed ap-

a ter ijt p 4e ch7-n, 1 24 hk The

7.7n f I.u

4 i

Thus, tile parameters rts qts nd gtare determined

by the computer 245 and then the computer solves the equations, thus producing at the output channel 251 the quantities f Thqse quantitie2s are applied io the

xem~ory of the pulse shapin~g filter 240. TVh ,tual output z t of the filter 240 is in Uhe lvzs: en~rjy sonme as close as possible to the desired outnu: b,. Since Voc matrix of the aqua: 7 nant i h

matrix~ Ir~ isa n t, fi, rr. of inii cor

lation matrix, these eqs> 'ony c- he0:v has been a ily the recurive This rrsl umthod. cc ne! described in O e Collowing LW" P IALM~n io NoThe Aiene RZSC' (root ionn snro G~ jr: :erl"v A

Time Serses" Joho WileI n Yory, N..14 AAi and Enders A. Robinson on "Wetistical Comakti! Detection with Speccial Rufurance oc Digit~al A"

MW **44 2r, 2 9, Hafnen PKIM4 Q N- Y.

S. It shu"d be i~ted L! :,n tv solve W V id~ o~ t~'0

with m coeffiAevl iv prupor: irn.-.

cursive moh! t

raveho of i vinP I t Q

lj*

ruth. 9 in .3

vher Ris Ube ohmic value cnf the resister 28-, C thb capacitan~ce of the capacitor 290 an V8 the output voltage

V.

In designing a pulse shaping filier two require- ments may be considered; namely, to shape as close as possible the function Z into the desired function b.

to produce as little output power as possible when the unwanted stationary noise is its only input. In many practical situations a filter iv needed for performing both of the above requirements simul- taneously, and so~ one is faced with the problem of finding Some suitable .zompromiso betycon the two re- quirements. Hence one selects an appropriante va lue for the parameter "which assigns tht. relative weighting between these two reqoirements. There are situations wheru thv vailue zero is assigned to In such cast Lhiv expre~ss ion (5i) takes a simpler form, nwl

t )t t (58)

:u and the *]oe OW t re 1. At AC repre- senting u :Ise 'th tre andA itw!olmn

22/4 shownl in FQ K or~.c ai 245 is prov ideo Ari !,wo ,itput AAn the channel ?46> nw tn, chaninA 248. It shoul! be olbservwd ta A po. r: U e of at pulsc shapI ig fitvr and -hit -7 "at t !L IiAter art' not exact ly alibr y, for a yli!von of Mhuse Fi 1lrr ar WOW A p ha

Wn u~ A W* lo W "4 ,c i-i, n4 f

-71.

Thuxs, if 3 pararsiters are to he Lvl ,tred the code can be as shown, in Pig. 26C, in wih

Accordingly, it was pointed out that the same graph in Fig. 10D represents the functions y(t) as well as the functions It should also be noted thatt the expression z~se'. b, which is appliLcable to apulse

shaping filter has been used above io order La indicare that the signal-expressed by q L (which represents the

output of a pulse shaping filter) closely approximates the double wavelet b Accordingly, it was pointad out

that the same graph in Fig. IOD rep-resents rhe function z(t) as wellas the function Strictly speaking, the same graph in Fig. lCD should not be used to cepresent the functions, y(t) and ztL). 1owever, sinqe both y( t) anid z closely' approxim~ate b it in~ believed to be appropriate fory the purpose of explanat ion to use same graph of Fig. IUD La iSCU."S th2 perforna~nee of a maitched fi lte and W!u of P pul se shaping filter.

XVIII. 'AV EV S1 'TNAG

Consider now; thr op.-'a ti ci* a rrangeat 1 hx by 4 F1ig. 17. I1have obti eo at MU. udt9Llt lead 162 Af the .0 subtractor 160 both the i n torm"Hion carryiu1 ;rignal b (t) an te oiesignal u Th. s;ignal b is tLhe aouble wavelet as shoyr in F16 10C. Tho mnt ore of the signals b(L) and u(t) is applijed Lo t L. AN ronv rt CrI .161, there- 4 04 by produc ing at thbe oc :pu; Oka 16, of the couIv'.rlter digital ized iAnrb1 t Ina ut thoseP signals eorr. sporiding

tiC tltF inolo Au;igtvn QQ aK rc na-ucli iuly The mixture' of 004VC. C Y11 h t' 1 L i i t iWi applied

to~ t hu j 1pot W -i n n lAn, fi r 34 T1 spiking filter a particular case of A Wiener type is pul.?e shaping filter in Wqhich the desired shape is simply a spike, (For a d.ascription of a spiking filter see, for instance., the publication by S. Treitel and E.A. Robinson on "The Design of High-Resolution Digital Fitet"' IEEE Transactions on Geoscience Electronics, A Vol. GIA-, No. 1, 1966 pp. 25-38.) It should now be recalled that a double wavelet- b(t) such as shown in Fig. 10C corsists of two valve wavelets; i.ea., a valve wavelet and a valve wave- let The valve wavelet foilcus the valve wave- let function of the spiking after a time T .The p filter to be used in the embodiment of Fig. 17 is to transform the vailve wavelet aq well as the valve wavelet into a rpspective clearly resolved spike. Thuis, a double valive wavelet bt. is converted by means of the spiking filter 351 into a pair of spiLkes. Figs. 18A to 18F show respectively sl:. possible positions of a pair of spikes (such an- M 1I nd N 1I with respect to the douhbi wavelet applied to the input. terminal'300 of the bpiking fi lter 351 Lot Tk be the time interval betsvqi the 2p 1 es MN and NtWlLLLh is the same in all of Fib. 18BA to I8F. Let H1 be thie point of intersect.i on of the spi ke 11M I~wi the a xis: of abscissas

(expressed in mi.lliseconds) Thus, the distance OH 1

(in milli seconds) will represeiit the t ime' Ing of the spikes withi ro'-;pue t to t he doubl1e wa vii t. Aqcordingly, in Fi2g 18A~ ti" time lag Oi1 -I0 VU thu I iiial I 4~ S IS 4 11

1 1Kp I'KU- at. the vvv.y beg i ngMo tie. double

SO0 wxve let. The ivc. c~sus shown in Fi.gn. i 81 to 18F car-

'4.444

A 4 '4

68F

respond to incrasing valus-of the time lag OH, One of these figkitqsrepresents the optimuni value of the time lag, for which the reolution of the spiking filter q te highest. For. such an optimum timie lag the out- Ksi'gnal" deri-v; -ut from the spikedfilter is-no ticeably -S1Ar,~I -t-a-n f or, a Q: other tti& -lag. *Aproceddire f or ob! pli the optihum"Oalu~ of the time lag, the optimum length,&f the memory, of the filter, arnd 'the optimum valuie o1, thd6 time interval T will he doscribed later

ibjn this specification. A double spit~. obtained dt the output terminal of the spiking filier 351 represents a sjhgle bit in the digitaliz~d signal which operates~ the valve 4'0. It is disifableyapiointed-out in connection with Fig. 9 to transform a double .pike into a single spike or pulse. -,apply here a processing system similar to that in Fig. _,(Soe Section VIV of tVhe specification entitled "ITrayis- 9 .4' 0 fomation Of A Coded Sequenne Of Double Wavelets Into A 0 04 Coded Sequence Of Short Pulses Step Accordingly,, 4' 4' 4' 4,, provide a delay element 303 controlled by a clock 304 12- '4 ~44, 0 *4

44-i -in comivnton with polarity re'versal element 306 and -an AND gate (coinciden~e network) 307. These are av- rangeu itl a ;nrer similar to that shown in Fig. 9". 4 04 However the aypAo t of dla~y in Fig. 17 is different from that in fig. Namely, in Fig. 17 the delay. -element 303 should produce In output -signial which is delayed AVt respect to the input signal by an amount herhab ino Fig. 9 thu produced by the cot-re- -delay

sponding1.1 delay alpmont, 193 awoup k to' Ti 3, A coded succovsion of singlQ ppl 30S ohtainid at the viput lo'ad b F the ANDfl gattu 307 is oppiejd ro a 1)/A converter:308 controlled by a clock 309. At the output

x leaclo~l~t D/A converter 3Qone obtains in analog form a signal representing the rneasurement of a selected m Ip ~~er inthe barehole. This signal is rccorded by means of recorder 54. ~~t-shxqtb3d be not'ed.thal in some instances, depending n- the' specific electroniic circuitry chosen for the various blocks shown in Fig. 17, the polarity reversal *ejemynt 306 niay not by. requited, since its function may be performned by the appropriate design of the AND gate. Fig. 19 shows an-altdrnate arrangement for noise 0-S a.

eliminlatibn by means of a spiking filter. In Fig. 17 a s-pecial means was provided for eli'minating the pump WN noise delay element 152 in comnbination1 with the Qbtractor 160) On the other hand, in Fig. 19 the 1, proceaure for noise elimination has been simj lificd. Thius, thq signal processing using a dllay elcrnent 152 and a subtractor 160 has been eliminated. Ac.cordingly, in Fig. 19 the signal VFt) obtailned at the output ter- intal 151 of tic? fiLter 150 is digital ized by Va~ns of 0 2Q anc A/D converter 350 and then aipplied to a sliking filter 351a. The spiking filter 351a is desitned diffe~rently 66 from the spiking filter 351 of Fig. 17. In fig. 17 the

spiking filter 351 Was designed to convert a double wavelet such as shown in Figs. ISA tro I 8F into a pair of spike's sep)aratted one from Mhe other by a t ime interval Tk On the other hand the spiking filite~r 351a~ in Fig. 19 ha s been designed to convert. a single valve wavelet *into a single spike. Various posi 1.1 ns of a single spike with respect t~o a O ngc valve wavole L arc si own in Figs. 20,h to 201'. I~t should "lon bo recalled that eaich sin vnl wavi'i.Q app1l~.di. Lo Lhiic fl)t to rmuiiol of the fiiir 351,1 atic 'Woh sVinglo sp ike obto Ined fromu the atpciL tuiriia 1 of the filter 3.51a represents a single bit i~n the digit- 'alized signals which operate the valve 40. The coded succession of the spikes in the digitalizedi format ob- tain-ed: from the output terminal of the spiking filter 351'a is then applied to a D/A converter 352 where it is transformed into a coded succession of spikes, each spike representing a single bit of the informnation enccded at the subsurface ins trumen tat ion. The succession of these bits represents in L digital format the measurement of the selected parameter. It is, however, necessary for recording and/or display purposes to represent this measurement in an a-nalog, form. Accordingly, the signal obtained from the D/A converter 352 if; applied to a D/A convertdr 362 to produce at the output, of the converter 362 a signal havring magnitude repr esecnt ing the' measure- ment of the selected parcamecer. This signal is recorded by means of the recorder 54. It should be noted. that the conversion of a double K' awavelet into' two spikes by mwans of the spiking, filter 20 351 as in Fig;. 17 or the convcr~ico oJf a sini,, e valvtt wave.let into a sing-le spike 1by of the spiking filter 351a as in Fig, 19 can only he approxir,.i-.t.ed.* A pure spike; i.e. a delia functio-ii, cz.:rnot: he obtained. H-owever, the objective of this inv,.'nt. ion is to increase 95 resolution; co obia in -in out pur s ignal hic is noticeably sharper than the inpuit ,;ignal. Consider now the minner in which a sp~iking filter should be dusigned. In thor.y, Vthis, porpuse waiy be( achieved exactly if one couild Lise ai fi ltei memory lunc Lion if; all owod L~o beco .w infllit.v Iv Long Por exac t filter perforuigincu on. iiote-' in ryc:-ora I to ck-lay thie .h;-ired spike., by in iti e !ntufLt_ of tie r elative to L-h( in1put ublicnrion b.; pae

J.G. Claerbout and E.A. Robinson on "The Error in Least

Squares Inverse Filtering", Geophysics, Vol. 29, 1964

pp. 118-120,). In practice, it is necessary to design

a digital filter whose memory function has finite duration

and hence, .at best, one can attain the objective only approximately. Suppose that for practical reasons one wants to

consider a filter which has memory function of the order of duration of an input wpvelet. Assume that one is at

liberty to place the desired spike at any selected loc- ation. For instance, Figs. 18A to 18F show six possible positions or locations of spikes for a spiking filter 301 of Fig. 17. Similarly Figs. 20A to 20F show six possible positions of spikes for spiking filter 351 of Fig. 19. The optimum position-of spikes was determined for each of these cases. should be noted that the It position of the spike is an important ,7actor governing the fidelity with which the actual output resembles the desired spike. A spiking filter in a partLi cAr cas. of a i ener

04° type pulse shaping filter prcviou l herein dcscrib.d. Consequently, the required proc.i-.re:, to dc.siu such a filter are analogous to those which have been previously herein described. We are concerned with the determination of the elast error en-rgy for a fil tcr whose output is a spike. In order to determine the optimum valune of the time lag and the optimum length of the memory function for the spiking filter 301 in Fig. 37, it is necessary tc obtain a record of a double wavelt bbt (which is a dig- ital vers.iou of Thu nec et. y tep for obtaining such a record; i svp; (c a d have been prviou ,y dvscrib,.d with refer, nce to Fig. 12. Th._s, the record of b is stored in the element 173 in the arrangement of Fig. 12. Similarly, in order determine the optimum value of thu timL lag and the optimum length.1 of the memory function for the spiking filter 351a, itr is necessary to obtain a reci-O of a vave vave1t B(which is a digital verf,;ion uf singe B(t). Conside~r the spiking filter 351a in* Fi 19. Various, positionis of a spike corresponding t~o vzirious delays ('s.20A to 20F) can be exprcs',ed i 0 Spike at time imdcIX Zcro delay spiking frilter. Spike at L~ime index n (m m~ 1 de lav s p i u

Spike at t. i ie index ri n t wi)

;:ngfiltor. -delay

Perfoirnance of a spiking fitter or 1,4L xi1os dcelays is iustrated d11agr,i~im t cally in -i..I 21B1 and 21C~. In all these figuevs :np, the same; i valve wavclo b ivhich Lt K .v~i e and stored ias explalned J,.U put in Fig. 2-LA is a spikQe (1 ,p: W zero delay. Thv correspo~i,. 'mry

zero delay spiking filter if-, F and the actual output is We t

Similar -notation applicable tc S in these figure's. -To ciach. po, i .on, (1 A. corresponds an qnergy error E. Thlc n.iii~.1. v energy error E represtnts i~ very convv-(nft. -W~askre the perf orni.-nc e of a pul, shihp ng on, aind More pai't icularly of n !qi* n- f iir..:. f i1.ter p-)erfoi p rfuctly L .1 4V8: t

pUlssTP1 TP2 and TP3 is missing. So long as at of -Lime. On the Other hand, the case EB 1. correspon-ds- ro the worst possible case, that is, th.are is no agrtee- aE. all bat.ween desired and actual Outputs. Instead of the quant:-ity E, it is desirable to consider the cn. co-inpieent of E which shall be callecd tiw filters porformafLce parameter P. P 1 E (46) Perfect filter performance then occurs when 711, wh i e the -worst possible situation arises when Ft. 13 Fig. 22 illustrates schematically *:i1w process o measuririg the performance parameter P. A computur 4001 is provided with three input channel-, L011, 402 and 404. The input channel 401 receives froiii the storage and reall element 403 data represcniting a %,alvewa -let inpu 402 receives from tiim contr-ol 40') data rt :4 regarding spikes for various tt~d l n. input Ad channel 404 receives dita frozm 1%.inc. y (.Xt~~tr

406 regardi~ng spikes for variou:, kurai ion-1 output at 430 of the (comiputer 40C povid means o" a meter 4] 1, a meca ruri- ol* cI rcC I:na t I-Al, ter P For a constant filtcr one -n ;~sp' that there :'ust- exist at i o .c I iU, el t at which F it-ai: large as ps ih. il:L-. 21 thor iu' shown a plot of P1 versus Itht Ii:.e of e'i' -put.p k for a family of' filter-:. of i i--Ld rti is observedthat t highes t po int )l Cur-;'u

corresponds to a time 1 :1i:ON Za.;d thu Clo 2L of t i .1me

leads to the, optimum titnc lag f i r.I r ul d b e *L called that tLhe curve in Vie> 2 lates to .1 fflt-er u ta fiXed du.-atLiorr. One can also see what;c pj R;~s one i ri sthL

filItu.r nmmoy dert;,ion altZ, I i( ig_ :fhow,.s a Plot of P1 vs. fi] icr ten"1 I1 for a dve;ixfed aTnd I~~dspiko vime Ing. It. can bc ot;cvdL)uti uv ist~orotnl, ndthat it jpproacheS; aSY-mpt)oiCall Y the

-87-

It must be noted that although the synchronization nulse- (clock 155) in the exainDles shown are generated largest value of P as the filter len-th b *(cr lar-,er and larger, Thae graphs as shown in Figs, ind 24 are obrtairied by means of the arrangemen~t sch c i shown ji Fig. 22. 5The tw.o itniportant designeriv ~be "Ih discuss ed 'hre are thp f ilIte r tirne Iag ant! tvir miemory duration. One can always i-m~prove pcriorinatc byTin~creasing the memory fu~nction Our~atiof- !ut ph\-i .al cons iderations preven-koni- from it akineti indefinitely long. On the othcr hand, on, *~'for that desired outplit time laj:hi .1 highiest P value for a given se L-1fjit~i This time lag in fil ter oa,,.put h:.I n no in 7 -,an impDrove filter output drastic~ alv The filter per'Lormanv(* z~:c of time 3ag and a con ;t ant. iurat i on i parameter P as a Iocrt iof t i for a constant time 3ap (Fig. 24) not tell ihe' whulec d Ttory. AM": investigate the depen~wnt,, duration for allI phys; i A!1 i 'a variables, One wa y I is oid-:a -by taking fil tlm Ia6-c ory duration as absci,!as. Tbh r, then be contoured bat one ath combination of tiiime la:g and mf N0_ optimum filter performance. Such a contou: given in Fig. 25 The map Aiwv; 1 nLvt atconi PisP2and P3.0Ob C z Is.I:et I the larget.r P valuer 4f performanee ib obutiiiw I ih i. r mewwoy dura t ionf bY i Ipt 'i (i explained aId specified by appropri nt~e mat h etical xiX. PULSE TIMIE CODE

Although in the examples show*n I described telemetering systems as employing a Binary code sys temn, other codes are sometimes more~suitable. For exnmple, for aigamma ray sensor or an electronic compziss- inclinonieter a Pulse- Time codc may be preferable. In some cases, especially -Where the sequential transmission of several numnbers is xreqoired, a Pulse-Time code has advan~tages. For some arrangements of an c lectronic coms;. it is riw essary to sequential~ly tr".ani! 5 nurnbei-, in~ ordLto rieau the magnetic bonrinn. By using a teluvwtuy!" systaem based on Pulse-Umcn~ code, a c'on4W W c al) l both in the energy requiredJ fi ow the ba~ tui and the tine re- quired for the Itransmilo of~C thy daIt. con: be *"chievet: Vk-kA conventIional Puln T ce, S sys taw is' ijllustrate~d in Fi No; o rk fu i -Psisi, of th. values of 3 pr etrs) A P~ ins vo age

Of VC'Lc ;tI S;e a, h, S rCWO( n rro

each putty a~ pansv in !dir i vu AW r ou sc; zrare thel end o "A POW "ro to, WA nn W the nent 'ihus in Fin AA~ tlt yolv ,Kcatst ~v nl~n £7 threL U~nnrv va bei: f'rom t he next UP

to rap ic j oni g o rirnce i as i 5 carr; no Of=it. inn. F ai Chcrz ronj a.1" du K pul ses are xrepu~3.n£n to vvy- u' o! pn:a" 3 I prop~ne 11p -u okloTe l 2

vatria1bIv Onrotiuv, 10i po" n of sun !lly ,n 34 M Mc~nIM~0Ax~ Ow erWfaion~ N-t o Wsr invent~ion, pulses lasting several rillisocndcs) are transmitted, and the time between the pulses is tbce neisure of the magnitude qf the parmeLer. Thus, no time is required to aeparzate one Lime interval (reprenewi pa~rmeter) from the next. In Fig. 26B p' ratvl Oki, is:repot scatee by the time Qt1 hvwoen pwn P nlAr

No. 2 is represetedc by thle iv- 42 y Y ptile P I and pulse and pnraa.Inr 1 is :r iby the

time Qt3 It.cen Priso P., py-sc 1 11 is seen th~at

in the wxd!m1iL ah, p rep -Vw V Int V& A tint

interval t nd w vin h e

und pu.s vv~ WL

c4 P 4, v~ K- g th, I

ASOe. rh K 4 t -4 4

44 .4.44, 4.

1

air. 1 :or to

J4: &A MI 1w; r i c

Alen1 C.S

4 1 041 Wn V r lip

i ~4 A' 3 T44

an 4 nt 4 j -mat ir ti

t4r

!X.

v. z 4

$i.Q 30 sh~ows the principles of the circuitry that can accomplish the Puilse-Time Code of this invention. in. uhe practical borehole inStrUetiatdtofl of course, maodern e:lectroic integrated circu:irs (,as for example, a type CD~4066 Bilacoral SWItMh wuld be uscd (see also, Fig. 29). For ease of explanation, 4 1 will sho~w a simple relay nechomnical stepping switch and a sim~ple~ macaical be so the principles of the logic of the system can simply' illustrated. in Fig. 30, sensors; are connected to the stepping switch terminals~ 1, 2, i ot the riepping switch 235 which hwn Assum~e has an electroz:dgnatie drive wini;t;: switich at that we start the~ sequenc, with At 6tpiny positionl Wp as showqn in FQ 3'4 ITO bat tery 288 gen-

erates a reference DC vol Lago.. 144i DC vo~tage will appear the resi stor 09( ai -w;l h. -r pac tor 290 *4 across rat c~et~. VWWA Ly LIV ':at Of ii a predotermnt-

Of the~ Wtr 2A 29 Vienv:~ Circuit VO Laye

genera~tes a sinu ~harp s elect ri p~ls wv.~.hen thie 2X ~ch :,I.tage aJim to its i- vIt tV.CL C. p, t

value y'vc V1 1 La, W uU. j A~t t:L ge 44

.ni; "i C; YOU 29

w il up4, t W Cir 44'=.4-i ui 294

4 s 4 .rarres cal" .i to: W !o r vd 44

p~ sitia nii, tIhe procve. et(pvt'd ta d ex~ceptt that,

to volt.ut VOLge 01 Whe hat.v 288, the tvad of too (U

i t b, i~ W; w:11cu 1c 4 thoC rcu t Vut~ vw .4

i sit; z~iy tr v.lingoi -f.t 1A~ Y& Circuit 4i~vk 0 1 4 R~C whffe~cR i~s the ohmtic value o"f the resistor 289~, C the capacitanlce of the capacitor 290 anid VS the output voltage of the sensor. Thus the timnerI is inversely proportional to the output voltage of the Aensov: After the activation of the 'Iigtor Circitt291 b y 4- the volt age from the sensor No 1, UPY proe6 repeats 4 itself and again, and when LA vol .iA. on the capacitor 290 reaches the trigger voltage, rho Triggar Circuit 291 generates a sharp pulse which operires the reiay' 292, discharges rhe capaci tor 290 and ei.~ry -es th" -r-eppinj, rw switch 285 and moves the armr.MThI 4*t

Thus, the stepping swi tch 2S. 4 .4 4- Qonnects the Sensors 1, 1,on ir tt h.to rthe 44.,, resistor 289. The pa! gvnr"rav-& lie'iii vrCircui~t 291 when ~is the arm 28; .at P0't :..I~.iSto '4 .4 44, pulse P0 (of Fig. jn Trigger Circ'ui t Ownei t b. t 'W2, *W 3 tc 1*4s ona .o;

#4'4 4 4 .4~e P3(of Fig.26P tt T 4:11f'.

4 *~4 L Z&3 rc ror -bek!"t i~wl,

voltage outpLutsV i i 4* The abev%~, yr 4

Pulse Tiumeuvo~ p,-yfic!& i hole eqjuipm~ent i n p~cL w f 25~ Fig. 4A. The Jdcuknt a by conventiona~ JlWe T'v not be discusaN in dwi i fL In Fig. 26C, 11 'O

ccsslve Cputsse:Y ,L'd 4 a h!I( surface. 'Ihe"CpU IOVU e sv

VLC. XVSPPCt 1 W 1-1V. ~d 4-'

pulwn ib 1 IU "Su'5C I 04 i 4 w .1 4 4 J.OL er

Thys, if 3 parameters are to be tele'~rucred, the code can be as shown in Fig. 26C, in wh~ich T1 10is a timec interval rvpre'nrntirig parameter No. I.

T12 I 1 is a time interval -c'prt"Ynt in,, imc er No.2.

1- 1 2 is a time inLerval loprewutiV ~rierer No.3. in mud pulse WasuremoCn! Whil krillia opv.rations it is necessary in some cases that. ty measurem~ents be made with great precision. Sinc tl: 3outid veT ies in the mud column arc nol(t alwA. coT.; i Pi se and a ttenuation cundit ion v'ai y. Q3 I nt. h-r, >1 tvvven i pulses renv~ive1 tit tiw sui' acc 011 nI b in v ae. 4's agreement with the t imei itecrval' hutv m. tho corresponding 444,4w

pulse at te genratp dunhol :wuloL. In other wordn, 0.~ there is frequentl m Nn nc. I n it t th sr I z. as tc 4's exact timr at which Lspetii. 11 i Q~ 4

pulse arrival tim i~n plus; o! w.os 2 w* vy or a MYL

of 0.4 sLCOFIs. In order to &;N-(vt Of k. ds-1,. for 11 T with a Lot'il akso~un .Cri

Lhe taie l.vit ouio vmI.. i scondsCI. lFCrt z'rT.!r, YK*. :K0 Sometimues fa i 1 t.

two deLeCtZ.'T uc"A',

t,the S arts L t hc d.:t a t Kai I1

Cofls0eAC'L ly, t t5 ncl cc t ho .1ir

(for a orst4.; c, an1 Ac." v f80 to 12YO

becona will b~e rvqvQQ(1 j n.

2 IMinut f-s p F loF.1 t (F01

U.hiC. K. 01; c t- r' Oh K o "rcy

Il jt %Fn i.

too;. t I~I

Let the time spacings in each triple group be 'Th( time from the first pulse to the second =t.

The ti.me from Lhe second pulse to the third t2 The time fran; the first pulse to the third t3

In this situatiort, again T 0 rep regon U; the time of

arrival. of triple group TI' IT,' the time KF arrbval of triple

group TP,; T 2 the time of arrivral of triple group TP 2 and

T the time of arri val of triple nroup TP 3 and; I t T 0is a rimeu interval re])rusentink parameter.

Iof2 T at Lie i ntevalI representing parameter

41 No 32 T is i ti~me in trv~.-i rep i- eown Lna parame Ler

No. 3. The ad\ aol ie of chi s s m is thaP in case of a momen t.ary fal.ure caui~;Ing on pm Ia in the groupJ not to be received, thec fail uru cat inmedinatel y bo rc co~ni zeci- 4. becaluse o~nec' r"pL grcv1o whitICOHIAW two po kes instead oIf tihree. Furthrva sinec(1~~f00 ;n i th vim I t r are 2' 3 un>0~ -1 nnd knlOWi,an. can do liewhii hpalis.e in the group .in tsing; and nril lIurtki~rnro, mis sinca again t

t2 t 3 Pro knc 171) o ne can Apply LQ p'roper c~ oeotion and

de terinef th"~ tinS m 7 TO' T T T 3with the

samne acocuracy is:a wo2 be in the c 3ne where all pulses were present in Lho tr i p i oup The triSp le group sys tout~ lhcmone further a'lvautagc Si nerv it is. di fficult to de~terimine rho uxact arr ival timvn of a par ticb La pul se, the triple gIrolp porrto i i0lAt lti21J*y cluser doe~rmna- icon of iho arr iv W' (AToe tCor'I uo c, LUKe he ari tLhn~t ea v of th ari 61a t*imles of VacL p)ulse

in the tril pyoud ~1byI] use of or 12odor.n ccw~purt t('ChniJques aib tairn ?ven greater accuracy of the arriial tiML. .Fig. 29 shows ablock diagram of a downhole eetroni cs .ogic system that wi)l eei' thu "ripl. group puls~es s In wi- in Fig. 261D. Numeral 101 is a sensor (see Fig. 4A) that generates an el Utric voltage indicative of the magnitude Of a down- Pike paramneter. 601, 602, and 603 are respactively a. 'Voltage contro~lled oscillator, a scaler, rand a trigger circuit that generate in a well known marnner a series of electric pulses sepairatcd by time intervai s that are indicative -of the magnitunde of the volAnge output of the sensor 101 and, thorefore, Of Lhe downhoi e parameter being measured. The time in terval be twccm Whe pulses P 0 and P1I as shown in Fig. 26B :is tberefofac a measure

Iof onc parnover mnnr ured by one if Lhe sen SOUS 101 of Fi0; 4A.

The portJon of E g. 29 tM t is ecl].oscd w;ithin the dashed rc-c Lagl e shows'the deANl of thc ci rcui try for generatin:-te W r:Lp I group pci sns referred to previously. 607 608 and 609 aure elect ronj one shot"uni vibrators S that in rus p u u a to he Y, 1 from the tr igger circu t: M each produces a sinrgle our Iut p~ulsc of durations D1 respect ye .y an shuwnr in Fir 29'. B9Locks

610.are ee trunlc duriva trs; each iuioducys. at its output a signal that ib proportional to the is t first L.ino derivative Of Lhe O PU L Signal (such be c tr(n ic u cv iceon are well hInow vti the air L) .Their

outputs, thure oru, will be an; sbwon in Fir. 29 as G, Ht and i two opponi t pol1arity pulses separated by respee Live vim-u in! vrvam ill I) D9 rid 11 DBocks

61 1 ar reati ier WC(nd tVrt1yfwll o~l tho pulses appoain Oni he nupuhs of .i Kv v rs 610. The out- "F0Fu wil ini A i ni~ul Ionjn in pal KIM at 612 an-d pjiie V& i.'sIgna J, whuich A rho Ko-l

"I -82-

dt~siti':Itttls 'hown in Fig, 260). Each single pulse gener~ated by the- trigger circuit 603, thoref.6re, -will generate thee pulses separated by known and ilnequal Ltme i-Litervals (triple group) as shown 'by' J. In practice the iterval 0 is made very short compared to D02 and D3 and would be only x few microseconds, whereas T)2 and D03

are inervalb of a few milliseconds to several hundred' millissconds! In the analysis of the operation we can therefore a1um th 1 0. 0 Therefore in the output shown as J in Fig. 29, the pulse pl indicates the end, of the-output pulse from 4 607 (which as pointed out above is for all practical purposes also the beginning of the output pulse since its length is assumed to he zero); the Pulse P2 is the erfd of the ouLput pulse from 608; bind the Pulse P3 is the end of the output-pulse from-609. Therefore, (since D01 was assumed to be zercp) the time ir'terval t1 D2 li~li li

the time interval t3 03; and the time interval t2 03 3 D2' Thus the portion of Fi.8. 29. WIthinI the dashed 2 Oli 0 rectangle creates-the triple group at its output at 612 (shown as J in Fig. 29) in response to a single pulse impressed upon its input. The circuitry shown in Fig. 29 may'be interposed in Fig. 4A between a selected sensor 101 and'the power drive 104. In other works when the:Pulse Time Code system of Fig. 29 is employed, thie A/.D converter 102 and processor 103 are eliminated (since they are adapted for binary en- coding) and the Power Drive 104 is driven directly by the output of autpliVi er 613 of-Pig. 29. XWhen the triple group Pulsc; Time Code is used instead oA Whe ino'ry Code i.t 0j1LI1 he rc' si.~ry, no~ dec ode the triple group'signals at che surface.- In Pigs. 9, 12, 13, 17 wu 1,9 thi signals tAt represent the downhole parameter are as.sumied'vo be in binary po le form. To change the sys- tenu to receive signals in the triple group Pulse Time Code

:fom as dle cribed iin conn(ction i Figs. 29 a.nd ?6D

i~t J-s necr-e s sar y to, in-terpose between the fitlter 2.50 and the subs eq uentL apparatus at the surface a SI ,ecial "Code Translator" sue1 a s that shox' in. Fig. 27. For th.Ls pur-' 0 &es the wire 151 iti Figs. 9, 12, 13, 17 and 19 w-ill be it erru-ptP d and, the Code Translator interposed. IT) Some -cases itL 'is, More desirable to interpose the "Code Trans- 1-atorTh.&Leen the subtractor 160 overter -ilte

1'63. at ead 162 off Figs. 9, 12, 13, 17, andteprfre locationi for insertion viill be clear to tho.-se sk~lled in the art.. With reference to Fig. 27, 3.16 is a "Selector" which is designed to gene-rate a single- outpul: pulse in response to the. triple grou-Lp de~scribed in connection with Fig. 29. -Numreral 317 designates a Time-to-Amplitudc converter; an electronic circuit that generntC: s an outpuit DC voltage at the wire 319 that is a pre determined function of the time betweentipt pu*Lses iiapre.,;sed upon its I iput by wire 318. well kInown in the Such dlevices are electronic s art and need no detaFiiled cldeser iption here. 320 is an Analog to D i -iLal conVerter ii a IsC) well. and

known in the art. Fig. 28A shows the Seetr36i o~dtal 321, 322,323re ne sot ni.vibrators designed to generate a i~gl outut pulse of seilec'ted predeterminedl time dur

ation in response to an input pulse. 321 ge,,nerates a long pulse of time. durat-ion l.3 322 a shorter pulse of tim~e du raIition 12, and 323. a still shorter outpuLt of pulse of *time duration' 11 as sho.xvn above each block 32t, 322, and 323. B3locks 324 vir e1 eDr i vatLo rs eleccronic circuits t hat geieraf:e- zn output p'roiortional to tht, f irst t ime clei-:LviaL-t of -a snlimre;sdupon thle i ;lpu~ SuL3Ch Un its Ir e aI ,7o I knomn a nd(IlIIL w' cneo o L; t, put si p IIalI aus shown on. the curvo ;hov, eachIeivt ;i.k Blm 3 hc 5 t rep)on ;i iL gp sien; .raI e )tiL inq. 325 are .e inverttra' of thQ te gn t:t pot si gnJx si n wnon hk v tei ybo, 'c ac ivr te(.

Blocks 326 each contain a rectifier and generate at the output a single positive electrical pulse, 326a, 326b, 326c. as shown. Blocks. 327 are "coincidence circuits" or

AND GATES" well known. in the art. Each block 327 pro-

duces an output pulse at its terminal only when there

is" a p'ulse at input and a pulse at input that are

'0 in time coincidence. The outputs of all three coincidence circuits 327 are connected in parallel at wire 329 and ap- plied to the input of the Time to Amplitude converter 317. The Time to Amplitude. converter 317 produces an output DC voltage that is a predetermined function of the time be- tween two successive input pulses. The output of the Time to Amplitude converter 317 is connected to the A/D conver- ter 320 which then translates the input DC voltage into S binary coded pulses in a manner well known in the art. The circuitry of Figs. 27 and 28A is made up of conventional electronic integrated circuit components that are well known in the art. The over-all operation of the "selector" requires some more detailed description.

24 The pulses P P2, P3 generated by amplifier 613 of

Fig. 29 are impressed on power drive 104 of Fig. 4A and are transmitted to the surface as mud pressure pulses by valve 40. At the surface these mud pressure pulses are picked up for example by the elements of Fig. 9 comprising transducer 51, filter 150, delay element 152 and subtractor 160. The pulses that appear on lead 162 of Fig. 9 (or Fig. 12, Fig. 13 or Fig. 17) we'shall designateas TP1'

TP 2 and TP 3 (and correspond to pulses Pl, 21 and P 3 gen-

erated by the downhole electronics of Fig. 29).

Figs. 28B, 28C, 28D, 28E show the response of the circuit of ig. 28 to the pulses T'IP T2', TI' When

pulse TP I arrives &,nd is imp essed onr wire (or wire

162) of Fig. 28A, all three one shot univibrators 321, 322 and 323 are triagered and each generates a respective

3 oul:put p2ulse having i:ts own character.istic'and prodeter- mrined and fixed length 13, 12 and 11, respectively. Thus, when pulse TP triggers the univibrators they generate the output voltages (pulses) A, B1 Cl1 as shown in Fig. 28B. When pulse TP 2 arrives it cannot triggr univibrator 321 because it is alyeady in the "ON" state. Pulse TP 2 does, however, trigger univibrators 322 and 323, since they have returned to the "OFF" state, and they generatu output pulses B2 and C 2 as shown in Fig. 28B. When pulse

P3 arrives it cannot trigger one shot univibrator 321 or

322 because they are already in the "ON" condition. Pulse TP 3 does, however, trigger univibrator 323, since

it has returned to the "'CFF" state, and it generates ou.- put pulse C3 as shown in Fig. 28B,.

The time intervals and 11 of the univibra- tors 321, 322 and 323 in Fig. 28A are so proportioned 0othat they correspond to the time delays cauised by the 00* action of the univibrators 609, 608, 607 of Fig. 29, and consequently, the ends of the group of univibrator pulses of Fip. 28B are in "coincidence" and activate the AND gates of: Fig. 28A. Fig. 28B shows the conditions of operation when Sall pulses TP TP 2 3 are present.

Fig. 28C show's the same conditions as in Fig. 2S8; but with one of the pulses TP 1 missing.

Fig. 28D shows the same conditions but with pulse 1h missing, and Fig. 28E whien pulse TP ii missing. It

hnat be niot t MO. no uAL or which pul. 0i .I' 2 o

TV is missn!g, t.uu univibrator autLj't pu alww;,s

end nt the tine T. This characteristic of the circuit ou Fig.. 28A is used to a .ways generate at least two time nci dent pulsscs at the time T' no mat ter which of th.

99-.

pulesTP 1 ~1P2 And TP s missing. So long as at

leas t.two of -the group of pulses a-.;eL detected, the Lime: of occurrence of the output pulse at 3291 of Fig.

28~A ill -be the. sarne. The single pulse 328a in Fig. 2~is gqinrated ,7-enever a "group"' of pulses is r ce iMe d b~y the uphole apparatus and the pul so 328a w~ill be "present wheiiever any t-vo pulses in the "group" .ajredect::-_d at the. surface. ~RefercLng again to*Fig. 28A, block 317 is a conven- tional Laime to amplitude converter and generates a DC output vo1ltage that-has a predetermined functional relation- ship to the time between successive pulses 328a. 320 i-- .coin~erenional A/D converter and translates the magnitude of this DC output voltage into a linary word. The binary w-,qrds follo-w one another in quicl< succession ais deter- mined by the charactLeris tics of 320 and its ociatod .clock. It can be seen, therefore, Lhat the aipparatus of' Fig. 28A translates the Pulse-Timea code u. in;, the triple group into a Binary code; arid the apparat:,is, !succeedir,.- Awire 151 or 162 of Figs. 9, 12, 13, and I1I w i l operatLe in exaLtly the same manner as if the data were initially transmitted in binary ccde 1corni from the svibi urface.

XX. ADDITIONAL NOTES

In order to obta in the sl Lwvei Lscribed earlier in this specificcti0n, there are curtain limits imposed on K2 (1mean rate of chan,-e of ch ning of the

valve) and on T10 (the, time or opit fi oxv E (tr i 1 et s

have shown that K 2 should be at cc. and

pruf r -ably within thLe railge *rop, s lo'~ 150 cii/lec.

M Should be at most:. 500 TiI] is;ccomd and pre ferably

heinth rwg fow )o0 ad 1i'secuCn(. tc V1 lU~ii i econds.

Qt 2~

(2 It must be noted that although the synchronization Pulses (clock 155) -in the examples shown are generated (aither by the generator -connected to the pumip shaft, or by the phase locked loop described in the parent, case, othar meants for providing the clock frequency that is synichronous Nw,,th the pump aiction. can be provided. For example, the well known "pump stroke counter" usually used or) the connecti-ng rod of the pump can be used to generate-one: electric pulse per pump stroke. The period betweerV each such successive pulse can be divided into an appropriate number 512 or 1024) of equal timE intervals'by a microprocessor or by a phase locked locp or by other means well kniow,n in the computer-and electronices V'A art. In such ar-rangement no access to the pump jack shaft is necessary, and the clock frequency equal to that oi generator 155 can be generated by the microprocessor and the pump stroke counter switch. 1 have described in the first part of this .C t -i li specification the conditions for o)ccurrence of hydrui shock waves and related "valve wavelets" iii sormu deta' I. At some depths, fo,- Pe-3mple shallow depth, conditions can arise when the -,lve wavelet as described above i, not well formed. For such a valve wavelet it is necessary to have a sufficient volume of mud flowingp iti the drill pipe%and sufficient 'hydrostatic pressuLre FiL the transmitter end. It shoudld be clearly understood that my invention is not limited to the par ticulair wavelet shownm and is applicable to other fortus of pres sure pulses which ca-, be detected at the earth's surface a result of the 310 actuation of the valve Various diglil, fi 1Lors itclIudin,: I (hed filters, pulse shaping fil terS arid Sli k.infl f i I t-Lrs ha 1l'un dc St. ib'od 110bVefz, I h unsi dIC .1e dot I I t ictui ,117 t~l j~ rforumanlc o of e~ach digiLt,1 I ii I i 1)e n clt-,~ C'du~Jb pr:ovidirng a dct w (1e uclice of j i nti s to bo so r IiJ O- h A :I explained aad specified by appropriate mathqmat ical lormnulations, It is clearly understood that by using modern computin~g techniques a person skillejc in the art can provide the necessary programs on the basis of the descriptions provided in this speci ficat ion, and the .operationls described in connectivn with Figtn. 9, 12, 13, 14, 16, 17, 19, 21 can be periorwod by sitauble software. \Tarioui digital filters w'bich I described can be also applied to other forms of iranso::ittn weasurem. o 9, 1 .0by mud pulsations by means other Aan the' by-p as valve 9 of ;the type described herein. Th sec other forno may in- .9 clude the method based on contrujied restrictiop &t the 900 4 miud flow circuit by a flow restrictint valve ay *rcopy idto 1 y 04# positioned in thu main mud styunj as devorih> C:n the W.S, 4 9 I .5 Pa tent 2 ,787 ,795~ iss;ued toi~ J.3 Arp B:I S'POWHUi 40 the cigi tal ilt eiiny systco yh~ 1 N4 v3rjibvC ow be applied to any furry of tel eme t'ri g y: tv :n i egnir while dril!Ln and other foio A~ I iVT n O ChWe 4, drilling equigpwent is removedi in t1or to lu o r the mea-aJriwt 9.

0 20 equipment into the JAM t ole. (lit. i c '94 9 ar o t9elerneterinrg syst1emsn utiliing

.4 forms of energy, such as eh et- acoustical pulses and W~her pcins The pulse i code tQ.: iUg We LA 1 P putst

94 259 group as described Thbl'. can As nw appl iecd in ac~ous I i well logging'in erdL r to' fac iIi ta tthe PrOCOSSi i6 of acoustic w~ell *oggirig signils an" Obtain "highly effe~ctivye Me Lhod allowinh, autownt coryovi on of errors du~e to pulse skippip in ai h mea k .rcynt th, Vrnnst time of at-sati c wavai" AK i

iod app*q atu a~rc ly dw rime o.f an a roast i w vc b r v. ii

TY.M h S1 )kb nmr Wr" a-qvnLM Co A C. A roau111r CL 0 it 1

uI) pulsc bLipp igt y Lhbw' mn ti. nr~ stored in an auxiliary memory and comparing this measurement wlith the next measurement (sequence Patent 3,900,824 is included in this application by reference. The alternalte, method which I propose and which is based on the pulse time codte is effective in correcting measurement errors du~e to cycle skipping in a more efficient and rel1iab I e narne-. The triple pulse group time code has a very broad field of applications outside ol logging while drilling. It can be used in any communication system for transiittinfg messages from. a transmnirting station to a receiving station as we'll as in vorious types of well logging (not necessarily in logging while drilling) such as acoustical logging (see Hlote #16). 8) Itis uderstood that in order to capture and stnre a wavelet for later use in the dipitzil filters described herein, certain steps mrust be t'aken at the si te as have been described in this specificatiot-.. It is 0desirable sometimes -to capture a s:iiq8 1e w;-vciet (rather than a double wavelet) as is nec -,ssary in~ the embodimeit. of Fig. 19 comprising the spikinj- filter 351A. To cap!!ire a single wavelet it is convenient to syi.chronize the generation Of the signal produced by th( suhsurfacE. oqiuip--,ent with detection oquir.ut on the surface. This can be done by replacing, one of Lte s(,n.,ors 1, 2, 3 and 4 z11- the subsurface equipmenet in i 4LA a device such as a "clock" or constant time controlled signal generator tLt will canse uniformly time spaced operationsi of the valve of F ig 4A. The operat ion would be as follows, 3U By swtpp i n{ and st artitig the rud ptimp.m at tht.

Fig. 4A can b(e made I 0 cUnneC't thc- wL'difiek4 ensor i e, 1 get wrato" or uI f Uri"d 'pcdU of pulsces will. be generatod by the val ve~ atF knovni t ime-, (CorreClCiQ11 !f COUrse mu;Kist be made for Lhe travel tirte of the pul.se fromt the subsurface to the surface which has been determin~ed previously by methods well known.) The suxvface equipment is controlled by its own clock that is in synchronism in time anid phase with the subsurface signal transmitter. By suitable switching at the Surface the cap- turing and storing of the double wavelet can be interrupted so that the storing circuit is connected only for the time of one wavelet and iA autom~atically disconnec'ted during the ochurrence of the second wavelt. Of course the same operation ca". be 1 hand (by the operator) This is uan2 ly 6on wht i the wavelet is distinct and clearly overrides the noise When the wavelet is submerged in no~ise, the au:wmati( rstem such as described herein is u~;ed. There are two interferin; nois ,A s which tend to obscurce the reception of the yetul i nal B3kt) (see equation 22). One of chose represnty tK, pump noise PWt and the other represents the noi cc NJ') which is associated with various; arilling ojpvyat iow other t han the action of the puntp. In order to el iminat e these interfering signals I provide three filtering n:,otem~s identified as filtering systems; 02, arh; ji Filterinb, system 44 is the anilog filt~r 150. The purpose of this filter is to so~ppres;s the steady component Of the transdicer output repres;enting the pre cure gen- erated by thr, ptump 27 and other fre"queneie ou Ade of the range of interent. Fil Lering sysitem ]J2 com~pse n eay xlcnZ 1l52 M' and a. subtriw I 160 T'iw purpose Qi t .to in

FiltoyTnp sysCt #1 vomf)i~v j or a

TAmpin!' ML r. or a spik'nA fikv x;A a~ w, i~e

v-:ious assoc ia~ted clemenatn such aF senza "A iecall elements, and computers for determining the optimum values of the memory elements for the corresponding digital filters (se~e Figs. 9, 12, 13, 14, and 15). The purpose of the syste~m #3 is to eliminaite or s;uppress the noise NOt. The filtering systems P1, P2, and 13 are connected in cascade. In the embodiments of my invention described above, the filtering system #1 is connected Lo the pressure transducer 51, the system #f2 is connected Co the output lead 151 and the system J±3 is coonecctd to the out~put lead 164 of the system P2. Each of the above* filterine nystems is a linear system. Therefore, th'e fu.ntion of these systems may Sbe interchngeci or treverse 1. I can proceed a;!ir with the filtering systAfl 11 ictd thtn intrcan;e the order of the fil cvrirg syrem and ff3. Ono. in sm cases it may not 1" roessa :y t" uno a11 throv Al tering systems. Any two may be suffive atand in some cancs .o only one. Also, Mi sysnm hw ,w.n O:ro 8 wirt Zax210 can sow.erh z 1 eliminava &te 1)/A -onvrtv- 211 arrdngol to ac :pt doubl e A.velvis. When the ilkA prodk e .1 by the' preo do- scribed in S~ection Xfl1 (stupj a f) Ks czyp ucd anti stored, i1t con he cooss-corre1 .ted. with the raw signal as generate d Q P"thransducer Y r with th ~econ- pv ditioned signal at .lre 16? N~ Ki,n. 9-L19. N~ he cost of cross-correlation with t he ic s ignal at Kwa trann- ducer 51 the ueconcl wavelet in the "double wavoint" willI have to tlel&iminatoO by nu i J lt ~1 1 1 uf,~ -v. the art so tn bc able to~Y O3corruI atv it" 16

A

Claims (1)

1. 9<

   The claims defining the invention are as follows:

   1. A telemetering apparatus for transmitting inform-

   ation through a transmission channel from an appropriate

   depth in a drill hole to the top of said hole, said information being in the form of an information carrying

   signal represented in terms of a reference signal which

   is expressed by an associated reference function, the

   operation of transmitting said information being performed in conjunction with operations of drilling said hole and

   said drilling operations being carried out using a drilling

   assembly including a drill string and a drilling means

   at the lower end of said drill striv-: for cutting down

   rock in said drill hole, said drill string having a

   passage therethrough and there being a pump provided for forcing drilling fluid down through said passage towards

   said drilling means and then upwards towards the top of.

   said drill hole thus f-orming a drilling fluid circulation

   system, thereby providing a transmission channel for

   transmitting pressure changes in the drilling fluid within

   said circulation system, said telemetering apparatus in-

   Z0. cluding a first means for positioning at the top of said

   hole and being operatively connected to said transmission

   channel for detecting a signal which is expressed by a

   function representing a superposition of said informatincr

   carrying signal and of an interfering signal resulting from at least one of said drilling operations, said inter-

   O -106- ft fering signal being expressed by an associated inter- ference function, a second means for generating one of said associated functions and a third means for storing

   'said generated function and combining said stored function

   with said superposition representing function to obtain

   said information.

   2. Telemetering apparatus according to claim 1,

   wherein said superposition representing function and

   said one of the associated functions are expressed in

   digital format and wherein said third means includes a I ar

   computer for combining the data on one of said associated a functions with the data on said superposition representing R

   function.

   3. Telemetering apparatus according to claim 1 or -I

   claim 2 wherein said third means is arranged for storing II

   and subsequently reproducing one of said associated r:I:

   P functions and for combining said stored and subsequently :P~ :rq c.:-i r; 5. reproduced function with said superposition representing

   function to obtain said information.

   4. Telemetering apparatus according to either of

   -rro claim 1 or 2, wherein said third means is a digital filter ii l

   P

   for receiving data oh said superposition representing r rr r,

   function and having a memory which is determined by one rrCIIB:

   i~r-Bi of said associated functions. ;I i; r::rn it" i:i,.I

   A telemetering apparatus for transmitting inform- 'i"-'CI

   ation through a'transmission channel froman appropriate F~i'i :' *4 I

   -J

   depth ii.a drill hole to .the top of said hole, said

   aiformation being in the form of an information carrying

   sirrnal represented in terms of a'reference signal, the

   operation of transmitting said information being performed

   in conjanction with operations of drilling said hole and l. said drilling operations being carried out by means of

   a drillirg assembly including a drill string and a

   drilling means at the lower end of said string for cutting

   down rock in said drill hole, said drill string having 4 4t

   a passage therethrough and there being a pump provided 4o*

   for forcing drilling fluid down through said passage

   towards said drilling means and then upwards towards the

   top of said dril. hole thus forming a drilling fluid

   4 4 circulation system thereby providing a transmission channel

   for transmitting pressure changes in the drilling fluid

   within said circulation system, said telemetering apparatus

   including a first means for positioning at the top of

   said hole and being operatively connected to said trans- 4 mission -cannel for detecting a signal which is expressed

   by a function representing a superposition of said inform- 44 '4(I

   ation carrying signal and of an interfering signal resulting

   from at least one of said drilling operations, a second

   means for generating two functions, one representing

   said reference signal while the other represents said

   interfering signal and a third means for combining said

   superposition representing function with the two functions

   generated by said second means to obtain said information.

   6. Telemetering apparatus according to claim 4

   wherein said .digital filter is a matched filter.

   7. Telemetering apparatus according to claim 4,

   wherein said digital filter jis-a pulse shaping filter.

   8. 'Telemetering apparatus according to claim 4,

   wherein said digital filter is a spiking filter.

   9. A telenmtring apparatus for transmitting

   information through a transmission channel from an approp-

   riate depth in a drill hole to the top of said hole, said information be ig in the form an information carrying

   signal represented in terms of a reference signal, the

   a drilling assembly including a drill string and a

   drilling means at the lower end of said string for cutting down rock in said drill hole, said drill string

   Shaving a passage therethrough and there being a pump

   provided for forcing drilling fluid down through said

   passage towards said drilling means and then upwards towards the top of said drill hole thus forming a drilling

   fluid circulation system, thereby providing a transmission channel for transmitting pressure changes in the drilling

   fluid within said circulation system, said telemetering

   apparatus including a first means- for positioning at the top of said hole and being operatively connected to said

   -109- S

   A, V 44.;' said informio carrying si a nd an of inverter In

   Soperansmission channel for detecting a signal which is

   expressed by a function representing a superposition of

   said information carrying signal and of an interfering

   signal resulting from at least one of said drilling

   operations, a second means for generating a function

   representing said reference signal and a third means

   for-combining said superposition representing function

   with said reference function to obtain said information.

   Telemetering apparatus according to claim 9,

   Qb wherein an additional means is provided for generating said reference .unction and to supply said generated

   function to said second means. 4t 44 Vt KULO 11. Telemetering apparatus according to claim 9,

   wherein sai. sEcond means comprises a correlator for

   o .hne eetn correlating said superposition representing function

   with said reference function. inlwihi .4 12. Telemetering apparatus according to claim 9,

   wherein said second means is a digital filter having its memory dependent on said reference function.

   13. Telemetering apparatus according to claim 12, wherein said digital, filter is a matched filter.

   0 Telemetering apparatus according to claim 12,.

   wherein said digital filter is a pulse shaping filter.. Telemetering apparatus according to claim 12,

   wherein said digital filter is a spiking filter.

   15. 'iTelemetering apparatus according to e'ither of

   1 *r

   o1 i

   i I I claims 1 or 9 wherein said information carrying signal domprises a succession of reference signals distributed in time a:ccording to a pattern representing said information.

   17. Telemetering apparatus according to claim 16,

   wherein said reference, signals are distributed in time

   in accordance with a digital code representing said

   information.

   18. Telemetering.apparatus according to claim 9,

   S.wherein said information carrying signal comprises a succession of reference signals distributed in time

   accordance with a pattern representing said information

   and wherein said second means is operable to produqe an

   indication of the degree of conformity of said reference

   function when compared to said superposition representing

   function.

   19. Telemetering apparatus according to either

   0, of claims lor 9, wherein said reference signal is

   expressed by at least one pressure pulse of short duration

   and wherein said information carrying signal is in the form of pressure pulses distributed in time in accordance

   with a pattern representing said information.

   Telemetering apparatus according to either of

   claims 1 or 9, wherein a restriction is provided in

   said fluid circulation system to cause a pressure drop

   and as a consequence thereof to create a high pressure

   -ll I.-g zone and a low pressure zone with a consequent pressure difference therebetween and wherein said information is obtained by using a sensor means for sensing the magni- tude of a downhole parameter, said sensor means being arranged to bypass said fluid from said high pressure 0. zone to said low pressure zone to generate and transmit through said fluid circulation system pressure variations representing said information carrying signal.

   21. A telemetering apparatus for transmitting

   information through a transmission channel from an app"-p-

   riate depth in a drill hole to the top of said hole, said

   information being in the form of an.information carrying

   signal represented in terms of a reference signal which

   is expressed by an associated reference function, the

   operation of transmitting said information being performed

   in conjunction with operations of drilling said hole

   and said drilling operation being carried out using a

   drilling assembly includin; a drill string and a drilling

   means at the lower end of said drill string for cutting

   down rock in said drill hole, said drill string having a

   passage therethrough and there being a pump provided for

   forcing drilling fluid down through said passage towards

   said drilling means and then upwards towards the top of

   said drill hole thus forming a drilling fluid circulation

   system, thereby providing a transmission channel for trans-

   mitting pressure changes in the drilling fluid within said circulation system, said telemetering apparatus including a first means for positioning at the top of said hole and being operatively connected to said trans- mission channel for detecting a signal which is expressed by a function representing a superposition of said information carrying signal and of as interfering signal resulting from at least one of said drilling operations, said interfering signal being expressed by an associated interference function, a second means for generating

   4a said associated interference function and a third means

   for storing said generated function and for combining 4 4

   94 30. said stored function with said superposition representing 44 a 4 function tb obtain said information.

   22. Telemetering apparatus according to claim 21, 44*r

   wherein said superposition representing function and said *r 4 associated interference function are expressed in digital

   format and wherein said third means includes a c imputer 0, 5. for combining the data on said associated interference *Z 4 4 4

   function with the data on said superposition representing

   function. 4, 4 4 23.. Telemetering apparatus according to claim 21 444 n

   or claim 22, wherein said third means is arranged for

   storing and subsequently reproducing said associated inter-

   ference function and for combining said stored and sub-

   sequently reproduced associated interference function

   I with said superposition representing function to obtain

   said information.

   Ir r -113-

   24-. Telemetering apparatus according to either

   of claims 21 or 22, wherein said third means is a digital

   Cilter for receiving data on said superposition

   representing functionand having a memory which is determined by said associated interference function.

   Telemetering apparatus for transmitting

   information through a transmission channel from an

   appropriate depth in a drill hole to 'e top of said

   hole, said information being in the form of an inform-

   ation carrying signal represented in terms of a reference

   signal which is expressed by an associated reference

   function, the operation of transmitting said information

   being performed in conjunction with operations of drlirinq

   said hole and said drilling operations being carried out using a drilling assembly including a drill strina

   and a drilling means at the lower end of said drill

   string for cutting down rock in said drill hole, said

   drill string having a passage therethrough and there

   being a pump provided for forcing drilling fluid down through said passage towards said drilling means and

   then upwards towards the top of said drill hole thus

   forming a drilling fluid circulation system, thereby

   providing a transmission channel for transmitting

   pressure changes in the drilling fluid within said circulation system, said telemetering apparatus including

   a first me :ns for positioning at the top of said hole

   and being operatively connected to said transmission

   u s channel for detecting a signal which is expressed by a channel for detecting a signal which is expressed by function representing a superposition of said inform- ation carrying signal and of an interfering signal resulting from at least one of said drilling operations with said superposition representing function being expressed in digital format, said interfering sinal being expressed by an associated interference function, a second means for generating said associated interference function expressed in digital format and a third means including a computer for combining said associated e4 p interference function with said superpositio.. repres- enting function to obtain said information.

   Dated this 13th day of March, 1985.

   SERGE. A. SCHERBATSKOY,

   By his Patent Attorneys, R.K. MADDERN ASSOCIATES,

   t *I

   04 4

   -115- i

   .1 1 Ai

   Offammom-mom

   Ems"ll-