US3225843A - Bit loading apparatus - Google Patents

Description

Dec. 28, 1965 J. E. oRTLoFF ETAL I 3,225,843

BIT LOADING APPARATUS Filed sept. 14, 1961 l2 2 Sheets-Sheet 1 RICHARD J. HowE if. JOHN E. oRTLoFF INVENToR.

ATTORNEY Dec. 28, 1965 J. E. oRTLoFF ETAL 3,225,843

BIT LOADING APPARATUS Filed sept. 14, 1961 .2 sheets-sheet z f RICHARD J. Howe JOHN E. oRTLoFF INVENToR.

Fm 4 Y/@M ATTORNEY United States Patent O 3,225,843 BTT LOADING APPARATUS lohn E. Ortlotf and Richard J. Howe, Tulsa, Okla., assignors, by mesne assignments, to Esso Production Research Company, Houston, Tex., a corporation of Delaware Filed Sept. 14, 1961, Ser. No. 138,015 11 Claims. (Cl. 175 93) This invention concerns the drilling of boreholes, oil wells, and the like. It relates in general to a system for forcing a bit against the bottom `of a bore hole. It relates especially to a hydraulic system for forcing a bit against the bottom of a borehole.

The rotary drilling system is the most commonly used method in the art of drilling wells for the production of oil and gas. In this system a drill bit is suspended at the lower end of a string of drill pipe which is supported from the surface of the earth. A drilling fluid is forced down through the drill string, through the drill bit, and back up to the surface through the annulus between the drill pipe and the wallsof the borehole. While the drilling fluid serves primarily to carry the rock cuttings from the drill bit to the surface, it also serves to lubricate and cool the drill bit. The drill bit obtains its rotary motion from the drill pipe which is rotate-d from the surface. It is known that the rate of penetration of a drill bit can be increased by increasing the force of the drill bit on the bottom of the borehole.

A usual method for increasing the pressure of the bit on the bottom of the borehole which has been tried with some success is by the addition of several heavy drill collars between the drill bit and the drill string. This method, however, has not been completely satisfactory. While the addition of drill collars aids the penetration rate, this advantage is partially oset by the need for heavier surface equipment. The borehole also tends to deviate considerably from the vertical during drilling.

In a broad aspect, this invention includes means for vforcing a bit against the bottom of the borehole. Briefly in a preferred embodiment, it includes a hollow sub or `arbor attachable at one end to a bit and at the other end to a drill string. It includes an outer housing which is mounted about the arbor in a non-rotating, longitudinally movable relationship therewith. Pushdown means are positioned between the arbor and the housing and are of a character to forcibly move the arbor longitudinally in the direction of the bit with respect to the housing. An anchor case is mounted about the housing in a rotatable non-longitudinally movable relationship therewith. Anchor means are located in the anchor case and are of a character lto firmly grip the borehole wall when actuated yso as to transfer the reaction thrust of the force exerted on the bit to the borehole wall- In the apparatus of this invention then, the housing is longitudinally slidable with but non-rotatable with respect to the arbor. That is, the housing rotates with the arbor but is longitudinally movable therewith. The anchor case which is mounted about the housing is mounted in a rotatable but non-longitudinally movable relationship with respect to the housing, that is the longitudinal position of the anchor case in the housing is xed; however, the two are rotatable with respect to each other. This arr-angement has the very desirable feature of having the seals seal only between sliding surfaces or between rotating surfaces; and not between two surfaces having rotatable and sliding movement with respect to each other.

This invention utilizes hydraulic pressure or other forms of energy at the bottom of a borehole to apply bit weight or force, thereby eliminating objectionable features of the drill collar. A pressure drop of a considerable amount results as the fluid passes through the drill bit.

3,225,843 Patented Dec. 28, 1965 lCe In one embodiment, the pressure differential between drilling fluid within the arbor and that in the annulus between the drill pipe and the borehole is used to actuate the pushdown section, Athus forcing the arbor section and the bit downwardly. The wall anchor device is used to transfer the reaction of the force incurred on the bit to the borehole wall. In operation then the arbor is forced downwardly thus forcing the bit against the rock face or bottom of the borehole and increasing the penetration rate. In another embodiment of this invention means are provided to increase the pressure differential across the piston of the pushdown section 'by pumping means so as to increase the downward force on the bit without the use of additional units.

Various objects and a better understanding of this invention will be obtained from the Afollowing description when taken in conjunction with the drawing in which:

FIG. l illustrates the preferred embodiment of this invention;

FIG. 2 illustrates a sectional view taken along the line 2 2 o-f FIG. l;

FIG. 3 illustrates a sectional view taken along the line 3 3 of FIG. l;

FIG. 4 illustrates another embodiment `of this invention;

FIG. 5 illustrates a view taken along the line 5 5 of FIG. 4; and

FIG. 6 illustrates a view taken along the line 6 6 of FIG. 4.

A non-rotating piston wall anchor drill collar assembly is illustrated in FIG. 1. Shown thereon is drill sub or arbor 10 connectable by threads 12 to a drill string not shown. The device contains an anchor section 14 and a thrust section 16. The thrust section is longitudinally movable with `respect to the arbor. The thrust section is rotatable with respect to the anchor section.

An elongated collar or housing 26 is mounted about sub 10. The lower portion of housing 26 is of greater diameter than the upper portion so as to form an annular cylinder 28 about sub 10. A piston 30 is formed or dened by the lower portion of sub 10 and slidably fits into cylinder 28. A seal 32 such as an O-ring is mounted in the outer periphery of piston 30. The outer surface of the lower part of sub 10 is shaped as splines 34 which mate with the internal splines 36 in end head 39 at the llower end of housing 26. End head or shoulder 39 is threadably connected to housing 26 for assembly purposes. Piston 30 then is seen to have a sealing, sliding, non-rotating relationship with housing 26. Thus seal 32 has to form only a sliding Iseal and not both a rotational and sliding seal. Splines 34 and 36 are such that fluid within annular cylinder 38 below piston 30 can escape through flow clearance channel 25 to the exterior of collar 26,

Anchor section 14 includes a cylindrical anchor section case member mounted about the upper end section 40 of housing 26 in a rotatable non-longitudinally movable relatlonship therewith. Case 18 has radially spaced ports `or apertures 20. In each port 2i) is mounted a resilient sealing member 22 which is preferably hard rubber bonded to the periphery of ports 2t) in a Iiluid tight relationship. Carried by the resilient member 22 are slips or anchor shoes 24 `which are preferably made of metal and when expanded are adapted to firmly contact the wall of the bore hole. Drilling fiuid can pass up the annulus through the space between the anchor shoes such space is clearly shown in FIG. 2.

The upper end section or portion 4t) of housing 26 has approximately the same internal diameter as the external diameter of sub 10. Seal 42 is provided to give a sealing fit therebetween. Seal 42 is a sliding seal and can conveniently be an O-ring. Housing 26 above annular cylinder 28 and below section 40 has an inside diameter slightly greater than the outside diameter of sub so as to form an annular passageway 44. The wall of sub 10 has a port 46 which establishes fluid communication between the interior of sub 10 and annular passageway 44. Annular passageway 44 is of sutcient length s0 as to maintain this fluid communication for all longitudinal positions of housing 26 and piston 30.

Ball bearings 48 are carried by inner race 49 and outer race 50 to establish a rotatable but non-longitudinal relationship between housing 26 and anchor section case 18. An upper retaining plate 51 holds the upper set of ball bearings 48 in place and a lower retaining plate 52 retains the lower ball bearings 48A in place between inner race 49A and outer race 50A. A retaining nut 53 holds inner race 49 of the upper ball bearings in place. The retaining plates, as shown, are held in place by suitable bolts which are connected to the case 18. If desired, the plates can be -threadably connected to case 18. Spacer 90 maintains the proper spacing between inner bearing races 49 and 49A. Upper seal 54 and lower seal 55 are provided between the exterior of retaining nut 53 and retaining plate 51 and the exterior of housing 26 and the interior of retaining plate 52 respectively. Seals 54 and 55 are rotating seals and keep mud from exterior of the tool out of the ball bearings. A port 56 is provided in the wall of upper end section 40 of housing 26 adjacent annular passageway 44. Port 56 opens into annular distribution chamber 57 which in turn is in fluid communication with port 93 which opens into annular distribution chamber 94. Port 58 then permits uid to ow from pressure cavity 59 which is that part of radial port 20 not occupied by resilient member 22 and anchor shoes 24. Seals 91 in spacer 90 and seals 92 in case 18 prevent mud from entering bearings 48.

In operation, the device shown in FIG. l is inserted into a drill string near the -drill bit. The weight of housing 26 and the anchor section will cause piston 30 to be in its uppermost position in relation to chamber `28. The apparatus is then lowered through the borehole until the bit reaches the bottom. At this point fluid under pressure is injected downwardly through the drill string and through sub 10. Fluid under pressure goes through port 46, annular passageway 44, ports 56, 93 and 58 into pressure cavity 59 where it expands the anchor members outwardly until anchor shoes 24 engage the wall of the borehole 11. Annular passageway 44 is slightly restricted so that anchor section 14 has time to expand anchor shoes 24 into engagement with the borehole wall before any substantial relative longitudinal movement between piston 30 and the anchor section takes place. The lower side of piston 30 is in uid communication with the exterior of the apparatus which is at a lower pressure than the interior of sub 10 due to the loss of pressure across the drill bit. The tluid under pressure through annular passageway 44 exerts a tremendous downward pressure on the top of piston 30, which is much greater than the upward force exerted on the lower side of piston 30. Thus there is a large downward force transmitted from piston 30 to bit 13. The pressure drop across bit 13 can in normal operations be as much as 500 p.s.i. to more than 1000 p.s.i. If the area of piston 30 is 30 square inches, the downward force exerted on the bit is 15,000 pounds for a 500 p.s.i. pressure drop. The reaction thrust from the downward thrust on piston 30 is transferred upwardly through housing 26 through ball bearings 48 to anchor case 18 to anchor members 24 which are secured to the borehole wall. At the end of the stroke of piston 30 it is desired to release the anchor section and the force on piston 30 Within the thrust section; this release is readily accomplished by reducing the pressure of the drilling iluid. When anchor shoes 24 are retracted, the weight of the anchor section and collar 26 cause the collar to move downwardly such that piston 30 is at the top of its stroke. The device is then ready to repeat the operation described above.

For a given bit, a given drilling fluid pressure and a given piston area, there is a substantially uniform downward force exerted on bit 13. One way of increasing the force is to use several devices as shown in FIG. 1 in tandem. However, this has the disadvantage of increasing the length of the section required and the downward force is not all concentrated immediately at the bit. Attention is now directed toward FIG. 4 which illustrates an apparatus similar to that of FIG. 1 whereby additional force can be exerted on the bit without using the units in tandem yet maintaining the concentration of the force at the bit. The apparatus illustrated in FIG. 4 has the additional means to positively increase the pressure on the piston in excess of the pressure of the fluid inside the drill pipe. Anchor section 14 is supported by collaror housing 60 similarly as described above in relation to housing 26 in FIG. 1 and a repeat of that description is not believed necessary. Hollow sub or arbor 62, as will be seen, is slightly different from sub 10. A passageway 61 from port 46 to cylinder 64 is defined by the enlarged portion of the upper part of housing 60 and the exterior of sub 62. A check valve 63 is provided in port 46 to permit ow of fluid from the interior of sub 62 to passageway 61. A restriction 61A is provided in the passageway 61 so that the anchor section is anchored before substantial force is applied against piston 65 which will be described hereinafter.

An annular cylinder 64 is provided between housing 6() and sub 62. A floating piston 65 is mounted in annular cylinder 64 and has vertical, non-rotatable move4 ment therein. A sliding seal 66 such as an O-ring is provided between the outer periphery of oating piston 65 and the inner wall of cylinder 64. The lower end of sub 62 has an external shoulder member 67 which has external splines 68 which mate with internal splines 69 of the lower extension of oating piston 65. A seal 70 is provided in the lower side or face of piston 65 to provide fluid tight relationship between piston 65 and the upper face of annular shoulder 67 when in contact. A passageway 72 is provided in the form of an annular recess in the outer wall of sub 62 just above external shoulder 67. When piston 65 is raised with respect to shoulder 67 as illustrated in FIG. 4, there is fluid communication between chamber 64 above piston 65 through fluid passageway 72 and between splines 68 and 69 to the interior of sub 62. A bit 71 is attached to the lower end of lower tubular extension 73 from piston 65. The lower extension 73 has external splines 74 which mate with internal splines 75 at the lower end of housing 60.

Attention will now be directed toward that part of FIG. 4 which provides fluid under pressure to cylinder 64 above piston 65. This includes a pump 76 which has inlet 77 exterior of the apparatus. Pump 76 is nonrotatably supported on annular collar 60 below anchor section 14. The upper end of pump 76 has pinion gear 78. Supported from case 18 of the anchor section is circular gear 79 which is arranged to mate with pinion gear 78. The discharge side of pump 76 is connected through conduit 80 to annular cylinder 64 above piston 65. A pressure relief valve 81 is provided for in annular cylinder 64.

In operation, the device shown in FIG. 4 is inserted between a drill string and a bit and the apparatus is then lowered until the bit reaches the bottom of the borehole. A slight upward pull on sub 62 through the drill string will cause piston 65 to rest on shoulder 67 to sub 62. Their own weights will force anchor sec` tion 14 and housing 60 to their lowermost positions. Thus the upper face of piston 65 is in contact with theV lower side 82 of the upper part of annular cylinder 64. The lower face of piston 65 is also in contact with the upper face of shoulder 67, and seal 70 will not permit. any flow through passage 72.

Drilling fluid then is injected downwardlythrough the drill string and through sub 62 under pressure. The fluid enters anchor section 14 through check valve 63 in port 46 in sub 62. The pressure expands anchor section 14 in a manner similarly described above in regard to FIG. 1. A restriction 61A is in annular passage 61 between annular collar 60 and sub 62. This restriction permits the anchor section to be secured to the wall of the borehole before enough pressure is built up in annular cylinder 64 to cause substantial movement between piston 65 and housing 60. When the pressure builds up sul-lciently, uid urges piston 65 downwardly with respect to the anchor section.

The downward force exerted on the piston 65 is given by the formula P A in which P is the pressure of the iluid in cylinder 64 above piston 65 and A is the area of the top of piston 65. This force can be increased by increasing the pressure. This is accomplished in the device shown by rotating the drill string in the normal manner. This causes pump 76 to be operative and fluid is forced downwardly through conduit 80 into cylinder 64 thus increasing the pressure in annular cylinder 64. This greatly increases the force on the bit in proportion to the increased pressure in the cylinder. In order to protect the cylinders, seals, pump, etc., a relief valve 81 is provided for cylinder 64 which is set at a predetermined pressure. In harder formations where the drill bit advances slowly, the pressure will build up to the maximum permitted by pressure relief valve 81. This increased pressure will close check valve 63 in port 46 thus conlining it to the pushdown and anchor mechanisms. In addition to providing high weight on the bit for better drilling performance, it increases the effectiveness of the wall anchor gripping segments. As drilling progresses, piston 65 is moved downwardly and the force is transmitted to the bit. When the device has drilled the length of its stroke, it is easily reset by cutting olf the fluid pressure and stopping the rotation and the lowering of sub62 so that the fluid in cylinder 64 above piston 65 can escape through passageway 72 and the flow clearance 83 between the splines 68 and 69. After the mechanism is reset, drilling can be resumed by repeating of the operation as explained above.

While there are above disclosed but a limited number of embodiments of the structure and system of the invention herein presented, it is possible to produce still other embodiments without departing from the inventive concept herein disclosed. It is therefore desired that only such limitations be imposed on the appended claims as are stated therein.

What is claimed is:

1. An apparatus insertable in a string of drill pipe for forcing a bit against the bottom of a borehole which comprises: a hollow rigid arbor connectable at one end to said bit and at the other end to said string of drill pipe; a piston mounted on the exterior surface of said arbor; a housing means surrounding said arbor in a longitudinally slidable and non-rotatable relationship therewith and deiining a cylinder for said piston; an anchor case means mounted about the upper end of said housing means in a rotatable non-longitudinally movable relationship therewith, said case means having radially-spaced ports extending through the external surface of said case means; anchor shoes resiliently and sealingly mounted within and to the periphery of each port within said case means; rst conduitmeans establishing lluid communication between the interior of said arbor and the interior of said case means whereby fluid pressure within the arbor is utilized to force the anchor shoes outwardly against the borehole wall; second conduit means establishing fluid communication between the interior of said arbor` and the cylinder above said piston; and means establishing uid communication between the cylinder below said piston and the exterior of said housing.

2. An apparatus for forcing a bit against the bottom of the borehole which comprises in combination: an arbor means including means for rigidly attaching said bit thereto; a housing means surrounding said arbor means in a longitudinaly slidable and non-rotatable relationship therewith, said housing means and said arbor means forming an annular cylinder; piston means mounted in said cylinder and attached to said arbor means; means to provide fluid under pressure to the top side of said piston; conduit means providing lluid communication between said cylinder beneath said piston and the exterior of said housing means; an anchor case means mounted about said housing means in a rotatably and non-longitudinally movable relationship therewith; and wall anchor means mounted in said anchor case means for anchoring said case means to the wall of the borehole.

3. An apparatus for forcing a bit against the bottom of a borehole which comprises in combination: a sub section connectable to said bit; an external annular shoulder member connected to the lower end of said sub; a housing means surrounding said sub section in a longitudinally slidable and non-rotatable relationship therewith, said housing means and said sub forming an annular cylinder above said shoulder member; an annular piston mounted in said cylinder; an elongated sleeve member connected to said piston and extending downwardly between said shoulder member and said housing means in a slidable non-rotatable relationship with said housing means; an anchor case means having an anchor for engaging the wall of said borehole, said anchor case means being mounted about said housing means in a rotatable non-longitudinally movable relationship therewith; pumping means supported by said housing means and having a discharge conduit means in fluid communication with the cylinder above said piston; and means to establish iluid communication between the cylinder above said piston and the exterior of said housing upon said piston being moved from contact with the upper side of said shoulder member of said sub.

4. In a rotary drilling apparatus for drilling a borehole which includes a drill string and a bit, the improvement which comprises: a rigid arbor means having a longitudinal passage therethrough for conveying fluids and including means to rigidly connect one end of said arbor I means to said bit; a housing means mounted around said arbor means in a longitudinally slidable and non-rotatable relationship therewith; pushdown means positioned between said arbor means and said housing means for exerting force on said arbor longitudinally thereof in the direction of said bit and for exerting the reaction thrust of such force on said housing means; an anchor case means mounted about said housing means in a rotatable and nonlongitudinally movable relationship therewith; and anchor means attached to said case means and of a character to transfer the reaction thrust to the borehole wall.

5. An apparatus for use in rotary borehole drilling systems including a string of drill pipe and a drill bit which comprises: an arbor; means to rigidly attach one end of said arbor to said bit; second means to attach the other end of said arbor rigidly to said drill string; a housing means mounted around said arbor in a longitudinally slidable and non-rotatable relationship therewith; pushdown means positoned between said arbor and said housing means operable to exert a force .on said arbor longitudinally thereof in the direction of said bit and to exert the reaction thrust of such force on said housing means; an anchor case means mounted about said housing means in a rotatable non-longitudinally movable relationship; and anchor means attached to said case means for transferring said reaction thrust to the borehole wall.

6. An apparatus for forcing a bit against the bottom of a borehole which comprises in combination: an arbor; means to rigidly attach said arbor to said bit; a housing means surrounding said arbor in a longitudinally slidable and non-rotatable relationship therewith; pushdown means positioned between said arbor and said housing means operable upon actuation to exert a downward force on said arbor; an `anchor case means mounted about said housing means in a rotatable and non-longitudinally movable relationship therewith; and wall anchor means mounted on said case means for anchoring said case means to the wall of the borehole.

7. In a rotary drilling system for drilling a borehole including a drill string and a bit, the improvement which comprises: a hollow arbor of a character -to connect said drill string to said bit, a portion of the exterior surface of said arbor protruding to define a piston; a housing means surrounding said arbor in a non-rotatable and longitudinally slidable relationship therewith and defining a cylinder for said piston; port means in said arbor to provide uid communication between said arbor and said cylinder above said piston; second port means in said housing means to provide fluid communication between the cylinder below said piston and the exterior of said housing means; pump means carried by said housing means, said pump means including means for increasing fluid pressure differential across said piston; an anchor case means mounted about said housing means in a rotatable and xed longitudinal position with respect to said housing means, and wall anchor means mounted on said case means for anchoring said case means to the wall of the borehole.

8. An apparatus as dei-ined in claim 7 in which said wall anchor means are hydraulically operated and inoluding .port means establishing uid communication between said cylinder albove said piston and the interior of said `anchor case means.

9. An apparatus for forcing a bit against the bottom of a borehole which comprises: an arbor; means to rigidly attach said anbor to said bit; a housing means surrounding sai-d arbor in a longitudinally slidable and nonrotatable relationship therewith; an anchor case means mounted about said housing means in a rotatable nonlongitudinally movable -relationship therewith; wall anchor means mounted on said case means for anchoring said case means to the wall of the borehole; and pushdown means mounted between said housing means and said arbor for urging said arbor downwardly with respect to said housing means.

10. An apparatus for forcing a bit against the lbottom of a -bore hole which comprises: an arbor connectable to said bit; a piston on the exterior surface of said arbor;

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a housing means surrounding said arbor in a longitudinally slidalble and non-rotatable relationship therewith and dening a cylinder for said piston; an anchor case means mounted about said housing means in a rotatable non-longitudinally movable realtionship therewith; wall anchor means mounted on said case means for anchoring said case means to the wall of the borehole; a circular gear carried by said case means and surrounding said housing means; a pumping means fixed to said housing means, said pumping means including an inlet, an outlet and a drive pinion which is mounted so as to mesh with said gear, the inlet to said pumping means bein-g in fluid communication with the exterior of said apparatus; conduit means fluidly connecting the outlet of said pump with the cylinder above said piston; and relief valve means for relieving pressure in said cylinder.

11. An apparatus for forcing a bit against the bottom of a borehole which comprises: an arbor connectable to said bit; a piston on the exterior surface of said arbor; a housing means surrounding said arbor in a longitudinally slidable and non-rotatable relationship therewith and defining a cylinder for said piston; an anchor case means mounted about said housing means in a rotatable, nonlongitudinally moya-ble relationship therewith; wall anchor means mounted on said case means for anchoring said case means to the wall of the borehole; a circular gear carried by said case means and surrounding said housing means; pumping means fixed to said housing means, said pumping means including an inlet and an outlet and having a drive pinion which is mounted so as to mesh with said gear, the inlet to said pumping means being in uid communication with said cylinder lbelow said piston and the outlet of said pumping means being in uid communication with the interior of said cylinder above said piston.

References Cited by the Examiner UNITED STATES PATENTS 556,718 3/1896 Semmer 175--118 712,887 11/1902 Wyczynski 175-230 2,223,645 12/1940 Solomon 175-99 2,643,860 6/1953 Koch 175-99 2,942,667 6/1960 Blood et al. 175--325 X 3,088,532 5/1963 Kellner 175-99 X 3,105,561 10/1963 Kellner 175-325 X CHARLES E. OCONNELL, Primary Examiner.

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