Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/26—Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers
  • E21B10/265—Bi-center drill bits, i.e. an integral bit and eccentric reamer used to simultaneously drill and underream the hole
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/64—Drill bits characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe
  • E21B10/66—Drill bits characterised by the whole or part thereof being insertable into or removable from the borehole without withdrawing the drilling pipe the cutting element movable through the drilling pipe and laterally shiftable
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/36—Percussion drill bits
  • E21B10/40—Percussion drill bits with leading portion
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B7/00—Special methods or apparatus for drilling
  • E21B7/20—Driving or forcing casings or pipes into boreholes, e.g. sinking; Simultaneously drilling and casing boreholes

Definitions

• the present invention relates to a drilling tool for down-the-hole drilling of the type that is used for drilling in earth and covered rock, the drilling tool being intended to drill a hole ahead of a following casing tube.
• Drilling tools are previously known that comprise a central pilot drill bit, a reamer and a guide body for steering the drilling tool and the casing tube relative to one another, said guide body having an axially fixed position on a drilling tool shaft during all working phases of the drilling tool.
• Said guide body is located inside the casing tube and transfers rotation and percussion energy to the reamer and the pilot drill bit.
• the reamer can take up both a position concentric with the guide body and the pilot drill bit, in which position the pilot drill bit and the reamer can be guided through the casing tube, and an operational, radially projecting position for drilling a hole larger than the casing tube.
• EP-A-36 847 and SE-B-411 139 for an example of such a drilling tool.
• the threaded connection as such is the weak point on known drilling tools.
• a known construction comprises a guide body, the shaft of which is integrated with said guide body and is intended to be connected to a down-the-hole hammer.
• a pilot drill bit is connected to the guide body by means of an externally threaded tap, which is taken up in an internally threaded hole in the guide body, and a reamer is supported rotatably by an intermediate part on the pilot drill bit.
• the most frequent damage that occurs in this case is a thread break on the upper part of the threaded tap. Attempts have been made to avoid threaded connections on drilling tools in down-the-hole drilling.
• EP-A-515 538 describes a down-the-hole drilling tool on which the threaded connection between the guide body and the shaft of the pilot drill bit is dispensed with.
• the drilling tool comprises a central pilot drill bit, a reamer and a guide body for steering the drilling tool and the casing tube relative to one another, and a shaft that is intended to be connected to a down-the-hole hammer, said shaft and pilot drill bit fo ⁇ ning a unit in one piece, and the guide body being attached to the shaft so that it can be dismantled, for example to exchange the reamer.
• the shaft of the guide body is provided according to this construction also with an external thread for fastening in an internal thread of a down-the-hole hammer, it again being possible for the problem of thread loosening to occur, in particular if the reamer gets stuck fast.
• the reamer is driven by the shaft of the pilot drill bit.
• US-A-5 787 999 describes a construction of a down-the-hole drilling tool that comprises a guide body, a drill bit and reamer arms attached between these two elements, which arms can be extended into an operational position and retracted for lifting, for example, through a casing tube.
• these reamer arms are fragile and prone to damage.
• cuttings, earth etc. can easily get behind and between these reamer arms, preventing a return to the resting position, which again can lead to loss of the tool.
• the percussion power is transferred according to this US specification from the reamer arms to the pilot drill bit (shoulder rebate), which is undoubtedly a disadvantage in connection with large forces.
• a first object of the present invention is thus to be able to retract the reamer of a down-the- h ⁇ le drilling tool without needing to rotate the pilot drill bit.
• Another object of the present invention is to avoid threaded connections.
• a third object of the present invention is to attain an operationally reliable drilling tool for down-the-hole drilling that is insensitive to penetrating cuttings and other particles.
• a further object of the invention is to design a drilling tool for down-the-hole drilling with as few constituent components as possible.
• Yet another object of the present invention is to develop a drilling tool with improved properties to remedy getting stuck and at the same time ensure improved manageability, both in the tool's working position and in the retracted position.
• Extension and retraction are positively controlled. If a shaft break should occur and the pilot bit and reamer are left in the hole on lifting, these are caught by a tool that rotates in the same direction as the working position.
• Fig. 1 shows in cross-section conveying of the guide body through the casing tube with the pilot drill bit shown in side view, and a cross-section of the reamer in a retracted position concentric with the guide body.
• Fig. 2 shows a corresponding view, but with the pilot drill bit and the extended reamer in the working position, below the casing shoe of the casing tube orifice.
• Fig. 3 shows sectional view 3-3 in Fig. 1 of the pilot drill bit and the reamer.
• Fig. 4 shows sectional view 4-4 in Fig. 2 of the pilot drill bit and the reamer.
• Fig. 5 shows a side view of the pilot drill bit with camshaft, cam and shaft.
• Fig. 6 shows a top view of the pilot drill bit according to Fig. 5.
• Fig. 7 shows a side view of the guide body in Fig. 1 and 2.
• Fig. 8 shows the end view 8-8 of the guide body according to Fig. 7.
• Fig. 9 shows a side view of the reamer according to Fig. 1 and 2.
• Fig. 10 shows the end view 10-10 of the reamer according to Fig. 9.
• Fig. 11 shows the end view 11-11 of the reamer according to Fig. 9.
• Fig. 12 shows the button pattern in end view .12-12 according to Fig. 5.
• Fig. 1 shows the drill bit in a retracted (non-operational) position with the reamer 33.
• the guide body 12 (see also Fig. 7) is coupled in the usual way to a continuous drill string in a casing tube 13, by means of which string it rotates clockwise in the embodiment illustrated and can be assigned percussion energy from a down-the-hole hammer or a left-rotating top- hammer coupled in a torsionally rigid manner between the drill string and the guide body 12.
• the drill string and its parts are of a conventional type and are not shown in the figures.
• the guide body 12 has a circular-cylindrical guide part 47, which with a centring fit is guided by the orifice of the casing tube 13 for rotation coaxially with the drill axis 16.
• the orifice of the casing tube consists of a welded-on casing shoe 14, which forms a circular collar 15 in the inside bf the casing tube 13, and a guide opening 19 for the guide part 47 of the guide body 12.
• the guide body 12 has rear shoulders 17 that during operation rest against the collar 15, so that a part of the percussion energy of the down-the-hole hammer can be transferred to the casing tube 13 to drive this down.
• the pilot drill bit 20 (see also Figs. 5 and 6) comprises a shaft 21 and a cam 22 in one piece with a camshaft 42 and an operational drill bit 48.
• the linear measurement L (with the camshaft 42) of the shaft 21 from the plane 23 of the drill bit to its top surface 24 is greater than the diameter D of the shaft 21.
• the shaft 21 is terminated by an end surface 24 at right angles to the longitudinal axis 16 to take up the percussion energy and is of such a length that a gap 59 is formed between the lower surface of the guide body and the opposed, upper surface of the reamer.
• the shaft 21 also has a radial groove 26 intended for a flexible sliding pin 30 (cf. Fig. 8).
• the shaft 21 is supported rotatably in the centric hole 28 of the guide body.
• the shaft 21 is terminated at the top by a recess 25, which encloses the shaft 180 degrees parallel to the cam 22.
• the guide body 12 has a shoulder 27 with two parallel planes 27 A, 27B at its lower end, the position of which is shown in Fig. 8. These planes interact with two parallel planes 36A, 36B of two shoulders 36', 36" of the reamer (see Figs. 9 and 10) close to the bottom orifice of the hole 28.
• One advantage of a coupling formed in this way between the guide body 12 and the reamer 33 is that the least expensive and most easily exchangeable part, the reamer 33, will be worn most during operation.
• the reamer 33 is shown in Fig. 2 in its extended operational position and its single-piece design in Fig. 9, 10 and 11.
• the recess 34 is seen positioned for right-hand rotation (seen from above) intended for the cam 22, and the plane 35, which forms the underside that shall lie adjacent to the plane 23 of the pilot drill bit.
• the recess 34 shall be positioned in a mirror-image position compared with Fig. 10, which can thus be done when using one and the same pilot 20.
• Fig. 11 shows the top side of the reamer with the two parallel shoulders 36, the longitudinal surfaces of which are parallel to the longitudinal extension of the oval recess 37.
• the pilot drill bit 20 hangs freely in the guide body 12, connected via a transverse' hole 38 (see Fig. 8), which passes over into a circular radial groove on the inner surface of the hole 28, the flexible sliding pin 30 being inserted into said radial groove and holding the rotatable shaft 21 together with the guide body.
• a tubular pin 31 is inserted that locks the sliding pin 30 for holding.
• the locking pin/plug 31 is best made of a material with a lower density than the material used in the actual fastener 12.
• the locking plug 31 is expediently made of an elastomer material, e.g. urethane rubber or plastic polymer (PAG).
• Cylindrical recesses 43 A and 44A respectively are located in the area of the transition of the flushing channel 43, 44 between the guide body 12 and the pilot drill bit 20. These recesses are essentially of the same external diameter, to be able to accommodate a sealing sleeve 50 of suitable material, preferably plastic.
• a groove 44B is arranged roughly in the middle in the recess 44A of the pilot drill bit, which groove is intended to cooperate with a correspondingly formed annular bulge 51 of the sealing sleeve 50. Due to this, the sealing sleeve 50 can be snapped firmly into the recess 44A in the pilot drill bit 20, so that it is fixed.
• the task of the sealing sleeve 50 is to seal the upper joint that occurs between the pilot drill bit 20 and the guide body 12. This thus prevents flushing medium from leaking out into the joint.
• the sealing sleeve 50 can be used advantageously to regulate the flow of the flushing medium by choosing a sleeve 50 with the desired inner diameter R 50 .
• the driller thus has access to many sleeves of varying inner diameter, so that the optimum flow can be obtained quickly and easily.
• the pilot drill bit 20 and reamer 33 are in the working position.
• the casing shoe 14 with the rebate 15 transfers the percussion energy from the shoulders 17 lying at the rear to the collar 15 (does not apply when driving using a top-hammer, as the casing shoe is absent and the guide body 12 is guided against the inside of the actual casing tube) in the axial direction of the drill string in the casing tube, in which case such a projection of the guide body 12 ahead of the front edge of the casing shoe 14 or casing.
• tube 13 should be- achieved that the distance from this to the plane 39 of the upper side of the reamer is approximately equal to or slightly less than the length of the shoulders 17.
• the reamer processes a radius from the centre axis 16 and on rotation provides a circular hole that is larger than the outer envelope diameter of the casing tube 13.
• the pilot drill bit gets its rotation from the camshaft 42 with cam 22 (Fig. 5) and its position in the reamer's recess 34, as well as the shaft's recess 25 (Fig. 5 and 6) and the carrier shoulder 18 (Fig. 8).
• the guide body 12 has axial, preferably straight flushing grooves 40, which are terminated to the rear between the shoulders 17 and there have ejector openings 41 acting to the rear and connected to the inner bottom plane, which consist of the hole 28.
• the flushing grooves 40 are terminated blindly ahead before they reach the front edge of the guide body 12 and a part of the groove opens in the plane 27.
• the back of the cam 22 forms a camshaft 42, which bears on the opposite end position of the hole 37, which prevents the reamer from executing an oscillating movement during operation.
• the direction of rotation is reversed and the above radial movement is repeated by the reamer, the shoulders 36', 36" of which slide, with the sliding planes 36A, 36B, against the parallel planes 27A, 27B of the guide body, ensuring retraction and retention of the reamer in the position according to Fig. 3.
• the flushing medium which can consist of venting from the down-the-hole hammer, is supplied via the drill string to the channel 43 (Fig. 7) in the guide body and routed onwards to the channel 44 in the pilot drill bit, which opens via channel arms on the one hand into openings 45 on the camshaft 42 and cam 22 respectively and on the other hand onto the front surface of the pilot drill bit fitted with buttons.
• the guide body has venting holes 41 close to the bottom plane of the hole 28.
• there is a number of flushing holes 45 in the pilot drill bit with channels 44 which holes are taken up radially in the camshaft 42 and cam 22, these providing an excess pressure in the recess 34, which in turn prevents drill cuttings and other particles from entering.
• the flushing medium flows out partly by the end plane 35 of the-reamer.
• the shaft 21 and the operational drill bit 48 are an integrated unit.
• the shaft and drill bit are separate parts, but are connected in a torsionally rigid manner to one another, for example by means of molecular connection.
• the coupling 27, 36 between the guide body and the reamer 33 can be executed in the reverse manner, so that the reamer 33 instead of the guide body 12 is provided with a central shoulder, and the guide body 12 is provided with two- laterally arranged shoulders.
• the sealing sleeve 50 does not necessarily have to be arranged in recesses in the flushing channel. It can be desirable in certain cases to e.g. only provide one recess in the pilot 20, or even to exclude recesses and then only use a groove in the pilot 20 or another suitable means for keeping the sleeve positioned in the joint.
• other sliding connections 30. can be used, for example balls with a diameter adapted to the radius of the grooves 26, 38.
• the flushing holes 41 can be positioned in many other planes than those described above, in certain cases advantageously above the sleeve 50.
• the displacement of the reamer does not necessarily have to take place along a straight shding plane, but can take place via a sliding plane that is curved to a certain extent, a certain rotation of the reamer 33 in relation to the guide body 12 occurring, the displacement however continuing to be regarded as essentially radial in relation to the guide body 12.
• the basic principle according to the invention can also be used if threaded connections are used in the power transfer.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mining & Mineral Resources (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Mechanical Engineering (AREA)
• Earth Drilling (AREA)

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• 2001
  • 2001-07-02 SE SE0102373A patent/SE522135C2/sv not_active IP Right Cessation
• 2002
  • 2002-06-27 DE DE60220277T patent/DE60220277D1/de not_active Expired - Lifetime
  • 2002-06-27 CN CN02813357.9A patent/CN1599832A/zh active Pending
  • 2002-06-27 WO PCT/SE2002/001273 patent/WO2003004824A1/en not_active Ceased
  • 2002-06-27 AT AT02744049T patent/ATE363015T1/de not_active IP Right Cessation
  • 2002-06-27 EP EP02744049A patent/EP1402146B1/de not_active Expired - Lifetime

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