US2551995A - Rotary core drill with jar mechanism - Google Patents

Description

May 8, 1951 c. c. BROWN ROTARY com: DRILL WITH JAR MECHANISM' Filed Jan. 30, 1948 l Arron/vn Patented May 8, `1951 OFFICE ROTARY CORE DRILL WITH JAR MECHANISM Cicero C. Brown, Houston, Tex.

Application January 30, 1948, Serial No. 5,390

(Cl. Z55-72) Claims. l This invention relates to improvements in rotary core drills.

Rotary core drills conventionally comprise a pair of concentrically arranged tubular barrels,

the outer one of which carries an annularly shaped bit at its lower end adapted to cut a cylindrical core to be received in the inner barrel and retained therein for withdrawal from the well. The outer barrel of such core drills is normally made of a 'diameter which is only very slightly less than the diameter of the bore hole being drilled and is of substantial length, for example, 2O to 40 feet. The Close clearance for such substantial lengths subjects conventional core drills to considerable danger of becoming stuck in the bore hole and this is a Very frequent occurrence with such drills. As a result, twistoffs and loss of the core drill and core often occur, necessitating shing jobs and side tracking of the lost tools in many cases, all of which is expensive and time consuming', particularly in the drilling of deep wells.

Normally it is only the outer barrel which becomes stuck but in the conventional forms of rotary drills, the inner barrel being fully enclosed within the outer barrel, it is difElcult to reach with the usual fishing tools, with the result that when the core drill is thus lost or becomes stuck in a well bore, it is not only diflicult to sh out but is diiicult to drill out or cut up because of the considerable amount of heavy metallic equipment comprising particularly the inner barrel, in addition to the outer barrel of the drill. On the other hand, if it were possible to remove the inner barrel from the core drill after it becomes stuck, it would be a relatively7 easy matter to drill out or cut up the outer barrel which is generally no more than a length of steel pipe, and continuation of the drilling could be then accomplished without too much trouble.

In my copending application, Serial No. 5,389, led January 30, 1948, I have disclosed an improvement in core drills wherein a safety joint is combined with the core drill for connecting it to a drilling string and includes a direct connection between the drilling string and the inner core barrel whereby, when the outer core barrel becomes stuck, separation of the safety joint will permit selective withdrawal of the inner barrel upon withdrawal of the drilling string.

The present invention is a continuation-inpart of my aforesaid application, Serial No. 5,389, and is directed to further improvements in core drills whereby such selective withdrawal of the inner core barrel may be facilitated and withdrawal of the core is assured. l

In core drilling, cases often occur when the inner core barrel may also become stuck, as by the settling of drill cuttings orother detritus in the relatively narrow annular space between the inner and outer barrels of the core drill. In such cases, even though the inner barrel is directly connected to the drilling string and is selectively withdrawable from the outer barrel, as by the arrangement described in my aforementioned copending application, the sticking of the inner barrel may prevent its ready withdrawal without danger of breaking at some portion thereof, or its withdrawal may be accomplished only with the loss of the core which is obviously an undesirable result, in that it defeats the very purpose for which the core drilling is normally conducted.

The improvements contemplated by this invention for facilitating the selective withdrawal of the inner barrel (the core barrel proper) and its contained core, comprises a novel form of rotative, Ysliclable connection between the drilling string and the inner barrel which, While maintaining a direct connection between the drilling string and inner barrel, incorporates a jar mechanism in the connection by means of which jarring impacts may be applied to the inner barrel by suitable movements of the connected drilling string. The jarring impacts thus obtained facilitate the withdrawal of the inner barrel and also act to break loose the core from its attachment to the structure from which it is being cut to permit its retention within the inner barrel for withdrawal therewith from the well.

Accordingly, it is a principal object of this invention to provide an improvement in core drills for facilitating the selective withdrawal of the core barrel proper from a core drill which has become stuck in a well bore.

An important object is the provision of a novel connection between a drilling string and the inner barrel of a core drill which incorporates a jarring mechanism for facilitating selective withdrawal of the inner barrel and its contained core from a` well.

Other and more specific objects and advantages of this invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings which illustrate a useful embodiment in accordance with this invention.

In the drawings:

Fig. 1 is a more or less diagrammatic view showing a core drill in accordance with this invention disposed in a well bore and illustrating the connection of the drilling string to the inner barrel as it is withdrawn from the outer barrel;

Figs. 2 and 2a comprise a longitudinal sectional view of a core drill in accordance with this invention; and

Fig. 3 is a detail showing some of the parts of the drill in the position at which jarring impacts occur.

Referring to the drawings, the core drill, in accordance with the illustrative embodiment of this invention, comprises a tubular outer barrel l enclosing a tubular inner barrel il concentrically spaced therefrom by an annular space I2. The lower end of outer barrel Ill has connected thereto bit I3 of generally annular form. It will be understood that bit I3 may be of any of the conventional forms of core bits which are available and well-known in the drilling art. Some of these are equipped with rolling cutters arranged about the lower end of the bit; others have radially extending cutting teeth arranged about the annular end of the bit, and still others have diamonds embedded in the end of the bit. The bit is connected to outer barrel I0 by means of a tubular shank I4 which is screwed on to the lower end of outer barrel I9 by means of threads I5. A plurality of angularly spaced fluid passageways extend longitudinally through the shank and bit and provide communication between annular space I2 and the exterior of the bit adjacent the lower end thereof. The upper end of outer barrel I9 has connected thereto a box member I8, internally threaded at I "l, for the reception of a pin member i9 which is externally threaded at and which together with box member I3 forms a threaded joint for connection of the core drill to a conventional rotary drilling string. The upper end of pin member I9 has a conventional internally threaded tool joint box portion 2I for effecting such connection to a drilling string. Box member I8 is illustrated as connected to outer barrel I0 by means of a ush-joint threaded connection I, but it will be understood that this may be a welded connection or that box member I8 may be made integral with outer barrel I 3. Pin member I9 has an axial passageway 22 which is adapted for registration with the bore of the conventional hollow drilling string to which the pin member is connected. The joint formed by box member I8 and pin member I9, as illustrated, is an example of one form of a conventional coupling commonly referred to as a safety joint in which the' threads I? and 2l) are of the square helical form which are non-seizing, irrespective of the degree of torque applied, and are, thereforey preierentially separable under an unscrewing torque over the standard tool joint threads normalh7 employed for coupling the sections of the drill pipe, such as the threads in box portion 2l. It will be understood that other types of conventional safety joints may be also employed in the structure in accordance with this invention. The threaded connection comprising threads I1 and 2i] are protected against the entrance of drilling fluid or detritus by means of suitable sealing means, such as conventional O-rings 23-23, arranged above and below the ends of the threads between box member I 8 and pin member I9.

Inner barrel il is provided at its lower end with a tubular tip 24 which is connected thereto by means of a threaded connection 2li. Tip 24 has a downwardly and inwardly tapering bore 26 on which is seated a ring shaped core catcher 2 which is slit longitudinally at one side thereof at 28, and is provided with inwardly and upwardly extending circular teeth 29 which are adapted to grasp the core (not shown), which normally enters the interior of inner barrel II during the drilling. The upper end o inner barrel I I is closed by means of a generally conical cap 3D, the lower end of which is threadedly connected to the upper end of inner barrel II by means of a threaded connection 3|. A plurality of reinforcing fins 32 extend radially from the outer surface of cap 30 for a distance such that their outer edges are substantially flush with the periphery of inner barrel II. A plurality of fluid passageways 33 extend radially through the wall of cap 39 and provide communication between the interior of inner barrel Il and annular space I2. Extending upwardly from the upper end of cap 3E! and rigidly connected thereto is an elongated shaft or stem 34 which is somewhat greater in length thanpin member I9 so that when pin member I9 is fully screwed into box member I8 the upper end of stem 34, which extends axially through bore 22, will project above and outside the upper end of box portion ZI of the pin member. The upper end of stem 34 has threadedly mounted thereon a block 35 of larger diameter than stem 33, thereby forming a radially extending abutment 36 at the upper end of the stem. Stem 34 is of somewhat smaller diameter than the upper end of cap 30 thereby forming an annular shoulder 31 on the upper end of the cap encircling stem 34. Mounted transversely in the lower end of pin member I9 is a spider 38 which supports a tubular sleeve 39 axially of bore 22 of the pin member. Stem 34 extends through the bore of this sleeve and thereby forms with sleeve 39 a rotative, longitudinally slidable connection between pin member I9 and inner barrel I I. Suitable anti-friction bearings 43 are arranged between the adjacent surfaces of stem 34 and sleeve 39 and between shoulder 37 and the lower end of sleeve 39. The upper end of sleeve 39 forms an abutment slidable along stem 34 with longitudinal movements of pin member I9, and when the latter is fully withdrawn from box member I8, the upper end of sleeve 39 is adapted to engage abutment 36 to thereby form a connection by means of which pin member I 9, under an upward pull applied thereto through the connected drilling string, may be employed to pull inner barrel I I out of outer barrel Il. Furthermore, the connection formed by block 35 and sleeve 39 constitutes a jar mechanism which, when pin member I9 has been withdrawn from box member I8, may be employed to apply upwardly directed jarring impacts to inner barrel II by suitable reciprocation of the drilling string in the well bore. The length of stem 34 is such as to permit a limited amount of such reciprocation after pin member I9 has been fully withdrawn from box member I8.

The above described device is employed in the following manner: By unscrewing block 35 from the upper end of stem 34 the latter may be inserted through the bore of sleeve 39 and into bore 22 of pin member I9 whereupon block 35 will be replaced on the upper end of stem 34 thus connecting pin member I 9 to inner barrel II. Inner barrel II will then be inserted into outer barrel I0 and pin member I9 will be inserted into box member E8 and made up therein through engagement of threads Ii and 2D. When these members are fully made up the lower endY of sleeve 39 carried, as described, in the lower end of pin member I9, will rest upon shoulder f 31 on the upper Sendof capi3'0; `The upper end of pin member I9 is then connected to adrilling string 4I in the usual manner by threaded engagement with box portion 2|, and the core drill structure will'thusv be connected to the end of the drilling string. The latter will then be lowered into bore hole B (seeFig. 1) until bit I3 is on bottom in positionto begin drilling. A suitable drilling iiuid .will Vnormally be circulated in the conventional manner through the interior of the drillingv string, thence downwardthrough bore 22 of ,the pin member, through the passages in spider 38, thence through annular space I2 and fluid passageways I 6 to the exterior of the bit adjacent the lower end thereof, and thence upwardly outside the drill and drilling string through bore hole B to the surface. With fluid circulation thus established,v drilling will be begun by rotation, generally clockwise, of the .drilling string and bit I3 will cut a cylindrical core (not shown) in the usual manner from the earth formations at the bottom of the bore hole. The core, as it is cut, will be forced upwardly into the interior of inner barrel II where the frictional engagement of inner barrel II and core catcher 2'I with the surfaces of the core will hold inner barrel II stationary while the drilling string, pin member I9 and outer barrel I0 will continue rotation. This relative rotation can occur because of the rotative connection, above described, between stem 34 and sleeve 39. As the core moves upwardly in inner barrel I I any fluid trapped between the upper end of the core and the interior of cap 30 will discharge therefrom through passageways 33 into annular space I2. When a core of length suiiicient to i'lll inner barrel II, or of any other desired length, has been cut, an upward pull will be applied to drilling string 4I in order to withdraw the drill and the core from the bore hole. This upward movement will wedge the teeth of core catcher 2'I against the lower end of the core and permit its retention in the barrel; however, since the core has not as yet been severed from the formation, this will generally be accomplished by reciprocating the drilling string one or more times, which will normally result in the shearing-off of the core, whereupon the tools and the severed core can then be withdrawn from the well bore, assuming, of course, that the outer barrel has not become stuck in the bore hole for any reason.

In the event, however, the outer barrel does become stuck, as often occurs, then the drilling string will be rotated in the counter clockwise direction to an extent suflicient to unscrew pin member I9 from box member I8 which, because of the form of the threads employed as previously described, will unscrew preferentially over any other of the joints in the drilling string. It will be understood that if some other type of conventional safety joint is employed in place of that described, corresponding movements of the drilling string will be employed in order to separate the members of such a joint. When pin member I9 has thus been unscrewed from box member I8, drilling string 4I will continue to be drawn upwardly until the upper end of sleeve 39 engages abutment 36 on the upper end of stem 34 (see Fig. 3), whereupon, by continued upward movement of the drilling string, inner barrel l I will be withdrawn from outer barrel I0. In order to break the core loose and also in order to free the inner barrel, in the event it is otherwise stuck within outer barrel I0, drilling string al will be lowered and then raised rapidly so as to cause the upper end of sleeve 39 to strike sharply against abutment 36 and to thereby produce a jarring impact upon the latter which will, of course, be transmitted through stem 34 to inner barrel I I, and will aid in breaking loose the core and in freeing the inner barrel from the outer barrel. When this has been accomplished the ldrilling string will be withdrawn from the well bore and will bring with it inner barrel II and its enclosed core. If it isthen found impossible to fish-out outer barrel I9 by any of the conventional methods, it will be a relatively`v easy job to cut up outerbarrel I0 in order to effect its removal from the well so that further drilling may be. conducted in thebore hole. In the latter event, it will only be necessary to replace the outer barrel in the core drill structure in order to reconstitute the drill for further use.v

It will be understood that various changes and alterations may be made in the details of the structure in accordance with this invention within the scope of the appended claims but without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. A rotary core drill, comprising, an outer corecutting barrel, an inner core-receiving barrel, a safety joint adapted to connect both said barrels to a drilling string, said safety joint comprising threadedly engageable pin and box members, said box member being connected to said outer barrel, said pin member being adapted to be connected to said drilling string, and a rotative longitudinally slidable connection between said pin member and said inner barrel, said connection including longitudinally spaced abutments interengageable upon separation of said pin and box members.

2. A rotary core drill, comprising, an outer core-cutting barrel, an inner core-receiving barrel, a safety joint comprising threadedly engageable pin and box members having engaging threads of the readily separable non-seizing type, said box member being connected to said outer barrel, said pin member being adapted to be connected to a drilling string, and a rotative longitudinally slidable connection between said pin member and said inner barrel carrying longitudinally spaced abutments inter-engageable upon separation of said pin and box members.

3. A rotary core drill, comprising, an outer core-cutting barrel, an inner core-receiving barrel, a safety joint comprising'threadedly engageable tubular pin and box members having engaging threads of the readily separable nonseizing type, said box member being connected to said outer barrel, said pin member being adapted to be connected to a drilling string, an elongated stem carried by said inner barrel rotatively and slidably journalled in the bore of said pin member, and longitudinally spaced cooperating abutments carried by said stem and said pin member inter-engageable upon separation of said `pin and box members.

4. A rotary core drill, comprising, an outer core-cutting barrel, an inner core-receiving barrel, a safety joint comprising threadedly engageable tubular pin and box members having engaging threads of the readily separable non-seizing type, said box member being connected to said outer barrel, said pin member being adapted to be connected to a drilling string, a spider mounted transversely of the bore of said pin member, an lelongated stem carried by the upper end of said inner barrel rotatively and slidably journalled in said spider, an abutment carried by the outer end of said stem engageable with said spider upon separation of said pin and box members, and a core catching element mounted in the lower end of said inner barrel.

5. A rotary core drill, comprising, an outer core-cutting barrel, an inner core-receiving barrel, a safety joint comprising readily separable pin and box members, the box member being connected to said outer barrel and the pin member being adapted to be connected to a drilling string, a rotative longitudinally slidable connection between said pin member and said inner barrel, said connection including longitudinally spaced jar elements engageable upon separation of said pin and box members.

CICERO C. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 156,631 Fritz et al Nov. 10, 1874 790,331 Terry May 23, 1905 793,414 Calla/nan June 27, 1905 1,805,727 Smith May 19, 1931 1,878,241 Johansen Sept. 20,v 1932 2,189,923 Phipps Feb. 13, 1940

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