US 3782459 A
A method and apparatus for cutting and retrieving a well pipe (having connecting collars and disposed within a well bore) from a floating drill ship utilizing a drill string, slack joint, downhole swivel, washover pipe, overshot and outside cutter; wherein the cutter is lowered into the well bore by means of the drill string until the cutter is in cutting relationship with the pipe and spaced longitudinally from one of the collars, the drill string is anchored in the well bore at a point between the cutter and the slack joint, the cutter is operated to sever the pipe, and the severed pipe section is retrieved by means of the drill string.
Claims available in
Description (OCR text may contain errors)
United States Patent Murray Jan. 1, 1974 METHOD FOR CUTTING AND 3,376,927 4/1968 Brown 166/.5 RETRIEVING PIPE FROM A FLOATING 3,396,794 8/1968 Webb 166/556 DRILL SHIP  Inventor: William K. Murray, Bossier City,
 Assignee: Tri-State Oil Tool Industries Inc.,
Bossier City, La.
 Filed: Dec. 16, 1971 ] Appl. No.: 208,652
 US. Cl. 166/.5, 166/556  Int. Cl E2lb 29/00  Field of Search 166/5, .6, 55.6, 166/98, 298, 301
 References Cited UNITED STATES PATENTS 3,378,072 4/1968 Smith 166/.5
2,418,278 4/1947 Reed 166/556 2,277,580 3/1942 Carothers 166/556 3,080,241 3/1963 Campbell 166/55.6 3,174,548 3/1965 Webb 166/556 3,299,951 l/1967 Todd 166/.5
Primary Examiner-Werner H. Schroeder Attorney-J. Vincent Martin et al.
ABSTRACT A method and apparatus for cutting and retrieving a well pipe (having connecting collars and disposed within a well bore) from a floating drill ship utilizing a drill string, slack joint, downhole swivel, washover pipe, overshot and outside cutter; wherein the cutter is lowered into the well bore by means of the drill string until the cutter is in cutting relationship with the pipe and spaced longitudinally from one of the collars, the drill string is anchored in the well bore at a point between the cutter and the slack joint, the cutter is operated to sever the pipe, and the severed pipe section is retrieved by means of the drill string.
This abstract is neither intended to define the invention of the application, which of course is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
15 Claims, 12 Drawing Figures PATENIEU H974 SHEEIIUFI;
4 W/LL/AM K. MURRAY IN VENTOR BY i221 PATFNTEU 1 4 sum 2 0r 4 Y m mm; W N m PATEHTEUJW 1W4 3.782.459
sum 3 m 4} WILL/AM K. MURRAY 1 N VEN TOR BY mu wmi PATENTEU JAN 1 74 SHEET 4 BF 4 WILL/AM K MURRAY 7/ %N VE/V TOE i wzm METHOD FOR CUTTING "AND': RETRIEVING PIPE FROM A FLOATING DRILL SHIP SUMMARY OF THE INVENTION This invention relates to the field of underwater drilling from a floating ship, and more particularly to an improved method and -apparatus forperforming a cut on a well pipe within awell bore from a floating drill ship.
Recent years have seen an increasing proportion of oil and gas exploration and production activity conducted on submerged lands, :especially the offshore areas of the continental shelf. Such activity was originally conducted from'fixed or movable platforms which rigidly engaged the oceanfloor during drilling operations. However, as activity moved farther offshore, it became necessary to operate from floatingdrill ships having no means of rigid connection with the ocean floor.
In offshore drilling, including that conducted from floating drill ships, just as in onshore operations, it is sometimes necessary to sever and remove a portion of a pipe which has become stuck within the well bore. When drilling from a floating ship, this operation is especially difficult because of wave action which is constantly changing the vertical distance between the drill ship and the well. Thus, a cutter on a tubing string does not remain stationary long enough tomake the cut.
The provision of a drilling slack joint, or telescoping joint, in the drill string above the cutter will compensate for this vertical displacement, but only if means are provided below the telescoping joint for retaining the cutter against vertical displacement while permitting rotation so that all relative vertical movement is absorbed by the telescoping joint.
It is, accordingly, the primary object of the present invention to provide a method for making cuts on a pipe within a well bore which overcomes the disadvantages found in the prior'art methods.
A further object is to provide such a method employing a swivel to anchor the tubing string at any point within the well casing, rather than at a predetermined point.
Another object is to-provide such a method which may economically be used to cut pipes at a point deep within the well bore.
A more specific object is to provide such a method wherein there is nopossibility that a cut may inadvertently be taken at aco'nnecting collar.
An additional object is to provide an apparatus adapted for use in carrying out'the foregoing objects.
DESCRIPTION OF THE DRAWINGS AND THE PREFERRED EMBODIMENT These and other objects and advantages of-the present invention will become apparent from the drawings, the specification and the claims.
in the accompanying drawings, which illustrate the preferred embodiment of the'present invention, and in which like numerals indicate like parts:
FIGJ is a diagrammatic view, partly in elevation and partly in section, of an offshore well installation including a floating drill ship. and illustrating a cutting tool being used in accordance with the method of the present invention to cut a pipe located within the bore of a well in the ocean floor.
FIG. 2A is a diagrammatic view, partly in elevation and partly in section, illustrating a step in the method of the present invention, wherein a tubular cutter is disposed about a pipe to be cut.
FIG. 2B is a view similar and sequential toFIG. ZA, showing the cutter being operated to make a cut in the pipe.
FIG. 2C is a view similar and sequential to FIG. 28, showing the tubing string and cutter being withdrawn to retrieve the pipe section.
FIG. 3A is an enlarged detail view, partly in elevation and partly in section, of the upper portion of the downhole swivel utilized in the cutting method of the present invention.
FIG. 3B is a continuation of FIG. 3A, illustrating the lower portion of the swivel, including the anchor means.
FIG. 4 is an enlarged detail view, partly in elevation and partly in section, of the collar locater, or overshot, used in performing the method of the present invention.
FIG. 5 is an enlarged detail view, partly in elevation and partly in section, of a tubular cutter used in performing the method of the present invention.
FIG. 6 is a sectional view, taken along line 66 of FIG. 4, showing the overshot dogs.
FIG. 7 is a sectionl view, taken along line 7-7 of FIG. 5, showing the cutter knives.
FIG. 8 is a sectional view, taken along line 88 of FIG. 33, showing the friction blocks used in connection with the anchor means.
FIG. 9 is a sectional view, taken along line 9-9 of FIG. 38, showing the anchor means.
Referring now to FIG. 1, there is shown a well bore 10 in the ocean floor 11. A casing 12 lines the well bore and is capped by the usual wellhead installation including blowout preventer 13. A pipe P which is to be cut is disposed within the lower end of casing 12, or in open hole.
Floating above well 10 on the surface of water 14 is a drill ship 15. On the deck of the drill ship 15 a drilling rig 16 is provided which supports a drill string 17 extending downwardly from the drill ship, through blowout preventer 13, and into the bore of the well casing 12. Means for compensating for relative vertical movement between the ship and well bore is provided by a telescoping or slack joint 18 in drill string 17, preferably at a point just above the downhole swivel S. The telescoping joint serves to compensate for vertical movements of the drill ship 15 relative to the ocean floor due to wave and tide action. The details of construction and operation of the telescoping joint 18 are conventional and are well known to those skilled in the art.
Spaced downwardly along tubing string 17 from telescoping joint 18, and within the bore of well 10, is a downhole swivel S which, as hereinafter explained, when actuated serves to anchor the portion of tubing string 17 below telescoping joint 18 against vertical displacement while permitting its free rotation. Below swivel S is provided a tubular collar locater, or overshot O, which, as hereinafter explained, serves to space the cutter C longitudinally from a collar of pipe I, thus assuring that the cut willbe made in the body of the pipe section and not at a collar connecting two such sections. The tubular cutter C is below the overshot O and is adapted to surroundingly engage and cut pipe P.
Referring now to FIGS. 3A and 38, there is shown the preferred form of downhole swivel S for use in carrying out the method of the present invention. The swivel provides means for anchoring the portion of drill string 17 below telescoping joint 18 against vertical displacement, while permitting its free rotation. it comprises two tubular body sections indicated generally at 19 and 20. Upper body section 19 provides the means for connecting the swivel into the drill string 17, and is the portion of the swivel which continues to rotate with the drill string during the cutting operation. Section 19 includes an upper portion 19a of enlarged diameter and an elongated lower portion 19b of reduced diameter, with downwardly facing annular shoulder 21 formed between the two. Reduced diameter portion 19b is adapted to fit within the central bore of lower body section 20 and extends downwardly below the lower end thereof. A threaded box portion 22 on the upper end of body section 19, and a threaded pin 23 on the lower end provides means for connecting the swivel S to adjacent sections of the drill string 17, and a central bore 24 therethrough provides a fluid passageway through the tool.
The lower swivel body section 20 has means for anchoring the swivel within the well bore and for rotatably supporting the upper swivel body section 19 and the apparatus attached thereto. It includes at its upper end a split nut 25 comprising two sections joined by bolts 26. Split nut 25 has an annular portion 27 of reduced inner diameter which fits within a groove 28 on upper swivel body section 19 so as to retain the upper and lower swivel sections against relative longitudinal movement.
Suitable bearing means 29 are provided between the top of split nut 25 and horizontal shoulder 21 on upper swivel section 19 so that, as will be hereinafter explained, when the lower swivel section 20 is anchored within the well bore, bearing means 29 rotatably support the upper swivel body section 19.
Threadedly connected to the lower end of split nut 25 is slip-expanding mandrel 32 which has multiple downwardly and inwardly tapering cam surfaces 33.A cylindrical slip body 34 is slidably disposed about the exterior of mandrel 32 and has in its upper portion multiple longitudinal slots 35 (six being shown) in which are disposed the individual slips 36. Slips 36 have on their outer edges multiple downwardly facing teeth 37 which are adpated to grip the inner surface of well casing 12. The inner edges of slips 36 have downwardly and inwardly tapering cam surfaces 38 which are adapted, upon relatively vertical movement of the slips and mandrel, to coact with cam surfaces 33 on slip expander mandrel 32 so as to force slips 36 radially outwardly into engagement with casing 12. The slips are retained against complete outward displacement by upper and lower dogs 39 and 40 on slips 36.
A plurality of vertical recesses 43 (eight being shown) are provided in the lower portion of slip body 34. ln each recess 43 is mounted a friction block 44. A plurality of circular recesses 45 is provided in the back of each friction block 44 with a compression coil spring 46 being mounted in each recess 45 and having its inner end bearing against the back 43a of vertical recess 43, so that friction blocks 44 are at all times urged radially outwardly into engagement with the inner surface of well casing 12. Complete outward displacement of friction blocks 44 is prevented by upper and lower dogs 44a and 44b, respectively. Upper dogs 440 are held by keeper ring 47 while lower dogs 4412 are held by the upper portion of a lower tubular extension 48 which is threadedly connected to the lower end of slip body 34.
Tubular extension 48 has an upper portion 48a wherein the central bore is of enlarged diameter, and a lower portion 48b wherein the bore is of decreased diameter, with an upwardly facing annular shoulder 48c being formed between the two. Located between shoulder 48c and the lower edge of a wear bushing 49 carried by slip body 34 is a retainer nut 50 which, as hereinafter shown, serves to keep the slips 36 from setting, and which may be selectively released to permit the slips to set. Retainer nut 50 has on the lower portion of its inner surface upwardly facing threads 51 which are adapted to engage downwardly facing threads 52 on the surface of lower portion 19b of swivel section 19. Extending upwardly from the bottom of retainer nut 50 are a plurality of longitudinal slots 53, so that the threaded portion 51 of nut 50 actually comprises a plurality of discontinuous thread sections 54, each carried at the end of a spring finger portion 50a of retainer nut 50, the purpose of which will be hereinafter explained. A pin 55 carried by lower tubular extension 48 fits within a slot 53 of retainer nut 50, to thereby prevent nut 50 from rotating relative to tubular extension 48 and slip body 34.
Spaced downwardly along drill string 17 from swivel S is a collar locater, or overshot 0 shown in detail in FIGS. 4 and 6. It includes two tubular body sections 56 and 57 threadedly connected. Upper section 56 has at its upper end a threaded box portion 56a for connection to a washover string W. Lower section 5:! has at its lower end a threaded pin portion 57a for connection to the washover string. The bore through both tubular sections 56 and 57 provides fluid communication through the tool.
Lower overshot section 57 has formed in its bore an upwardly facing annular shoulder 58. Confined between shoulder 58 and the lower end of upper overshot section 56 is a collar 59 having a plurality (three being shown) of openings, or windows, 60 therein. Extending into each window 60 are two lugs 61 formed from the collar 29; one lug 61 being on each vertical side of the window near the lower edge thereof. The lugs 61 are preferably of less thickness than the wall of collar 59.
Disposed within each window 60 of collar 59 is an arcuate overshot dog 62 having serrations 63 along its upper edge. On the inner face of each dog 62 are formed two recesses 64 adapted to coact with the lugs 61 of window 60, so that in its assembled position each dog 62 is retained between the lugs 61 and the inner surface of lower overshot section 57. A leaf spring 65 is attached to the back of each dog 62 by bolt 66 and bears with its free end against the inner surface of overshot section 57. Each dog 62 is thereby resiliently urged radially inwardly at its upper end, tending to pivot about lug 61. A key 67 fits through overshot section 57 and into a recess 68 in collar 69 to prevent the collar from rotating relative to the remainder of the tool.
Referring now to FIGS. 5 and 7, there is shown the cutter C preferably used in performing the method of the present invention. As shown, cutter C is tubular, being adapted to surround the pipe to be cut, and cut from the outside of the pipe inward. Therefore, the
bore of the cutter is of sufficient internal diameter to accommodate the pipeto be cut, including connecting collars.
The cutter includes a tubular body 69 having a plurality of longitudinal openings 70 therein. At the lower end of each opening 70 is an upstanding lug 71 having formed on its inner surface downwardly and inwardly tapering cam surface 72. Disposed within the upper end of each opening 70 is a slide 73 having at its lower end a curved cutting knife 74 pivotally mounted on the slide 73 by a pin 75. The lower rear portion 76 of each cutting knife 74 tapers downwardly and inwardly so as to coact with cams 72 of lugs 71 to pivot the knives radially inwardly about pins 75 as slides 73 move downwardly relative to the cutter body 69.
Each slide 73 is attached at its upper end by means of screws 77 to square-cut coil spring 78 disposed within the bore of cutter body 69. Above spring 78 is a slidable sleeve 79 having thereon a conical seal element 80. As hereinafter explained, the seal 80 is adapted to seal between a pipe P disposed within the bore of cutter C and the sleeve 79, whereby pressurizing fluid may be retained above seal 80 to exert a downward force on the sleeve 79 and spring 78. A shear pin 81 initially retains the lower end of spring 78 against downward movement.
The manipulation of the above described apparatus to perform the cutting method of the present invention is indicated diagramatically in FIGS. 2A, 2C and is as follows: The operating string, including the cutter C, overshot O, washover pipe W, swivel S, telescoping joint 18 and connecting drill string 17, is made up on the drill ship and is run into the well bore by drilling rig 16. As the string is lowered, the top of pipe P enters the lower end of the bore of cutter C and thereafter the cutter is lowered in surrounding relationship to pipe P. As the pipe moves relatively upwardly in the bore of cutter C, it engages the annular seal 80. Thereafter, the flexible annular seal 80 maintains a seal between the pipe P and sleeve 79.
As the drilling string is lowered further, pipe P enters the bore of overshot O and the upper ends of overshot dogs 62 bear against the outside of pipe P. The dogs pivot outwardly to accommodate a collar on the pipe as they pass down around it, but leaf springs 65 cause the dogs to snap back against the body of the pipe section as the collar is cleared. The parts are shown in this relationship in FIG. 2A with the cutter and overshot surroundingly engaging the pipe P.
When the cutter has been lowered to the approximate cut point, an upward pull is taken with the drill string 17 which causes the cutter and overshot to move upwardly until dogs 62 engage the lower edge of a collar in pipe P which stops further upward movement. Since the overshot O is a fixed distance above the cutter C, this automatically spaces the cutter from a collar and assures that the cut is taken in the body of the pipe P.
Next, the downhole swivel S is set by rotating the drill string 17 to the right and lowering slightly. As
the string is rotated to the right, upper swivel body section 19 also rotates..while lower section 20 tends to remain stationary by virtue of friction blocks 44 dragging on the inner surface of the well casing 12. This causes the threads 52 on upper swivel member 19 to disengage from threads 53 on retainer nut 50. After disengagement, threads 52 are below threads 53. Then, as the tubing string 17 is lowered, slip mandrel 32 also moves downwardly while slip body 34 remains stationary due to friction blocks 44. Continued downward movement causes cams 33 on the slip mandrel 32 to engag carns 38 on the slips 36, and thereby urge theslips 36 radially outwardly into gripping engagement with the well cas- As the slips set, the entire weight of the string suspended from the swivel is carried by lower swivel section 20 through bearings 29. Thus, the setting of the downhole swivel will be indicated on the drill ship 15 by a loss of weight in the string approximately equal to the weight of the tools below the swivel. The drill string above the swivel is then lowered a distance equal to approximately one-half the travel of the telescoping joint to position it to compensate for the ships vertical movements.
Once the swivel is set and the telescoping joint is positioned, the cutter C remains vertically stationary, and movements of the drill ship 15 are absorbed by the telescoping joint 18. However, the tubing string and cutter remain rotatable by virtue of resting on bearings 29 in the swivel S.
Next, the tubing string 17 is rotated to rotate the cutter C and hydraulic fluid is pumped down through the string to actuate the cutter knives. The hydraulic fluid is trapped above the seal 80 in cutter C and, as pressure increases, forces the sleeve 79 downwardly, compressing spring 78 until shear pin 81 is severed. The combined actions of spring 78 and the hydraulic pressure acting on sleeve 79 then force slides 73 downwardly relative to the cutter body 69, causing cutter knives 74 to pivot about pin 75 and engage and cut the outer surface of the pipe P. As the cut progresses, knives 74 pivot further inwardly until the pipe is completely severed. The parts are shown in this configuration in FIG. 2B with the slips 36 of swivel S engaging the inner wall of well casing 12 and with a cut being made in the pipe P.
er th cutis c tipl sdtt idtl atr ns ll i eised Ito disengage slips 36. Threads 51 and 52 on the retainer nut and swivel section 19, respectively, may, by virtue of their shape and the flexible spring-finger sections 50a which carry the thread segments 54 of retainer nut 50, be snapped into place without relative rotation.
After the swivel is released, the string 17 may be raised until the dogs 62 in the overshot 0 again engage a collar on the pipe P. This retains the pipe against further downward movement relative to the cutter so that the severed pipe section may be withdrawn supported within the string, as shown in FIG. 2C.
Thus, it is seen that a method and apparatus have been provided for making a cut on a pipe within a well bore from a floating drill ship. Moreover, the disadvantages present in the prior art are overcome in that means are provided for rotatably supporting the drill string at a point within the well bore and for assuring that the cut is taken in the body of the pipe and not at a connecting collar.
The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.
What is claimed is: l. A method for cutting and retrieving, from a floating drill ship, a well pipe disposed within a well bore and including connecting collars, wherein a cutter is utilized mounted on a drill string, said string including means for compensating for relative vertical movements between said ship and the well bore, said method comprising:
lowering said drill string into the well bore to position said cutter in cutting relationship to said pipe,
locating said cutter in spaced longitudinal relationship with respect to one of said collars in said pipe,
anchoring said drill string, at a point between the cutter and the compensating means, at any desired depth within the well bore so as to prevent longitudinal displacement of said cutter while permitting rotation thereof,
lowering said drill string from said ship to operatively position said compensating means,
operating said cutter to sever said pipe,
releasing said drill string from its anchored position,
utilizing said drill string to remove the severed pipe from the well bore.
2. The method of claim 1 wherein said drill string includes an overshot and the locating of said cutter in spaced longitudinal relationship with respect to one of said collars in said pipe is accomplished by raising said drill pipe to contact one of said collars with said overshot.
3. The method of claim 1 wherein the anchoring of said drill string is accomplished by rotating said drill string to the right and lowering slightly to actuate swivel means and anchor means carried by said drill string.
4. The method of claim 1 wherein said cutter includes seal means to seal between said pipe and said cutter and wherein the operation of said cutter includes rotating said drill string to rotate said cutter and supplying pressurizing fluid to one side of said seal means.
5. The method of claim 3 wherein said drill string is raised to release the drill string from its anchored position by releasing said anchor means.
6. An apparatus for use with a floating drill ship for making an outside cut on a pipe having connecting collars and disposed within a well bore and for retrieving the severed pipe section, comprising:
a drill string adapted to be suspended from said drill ship, an outside cutter at the lower end of said drill string having at least one movable knife adapted to engage and cut said pipe, and being adapted to be actuated by pressurizing fluid supplied through said drill string, locater means carried by the drill string above said cutter for engaging a collar on said pipe to locate said cutter a spaced distance from said collar,
swivel means for rotatably supporting said cutter and locater means within the well bore,
said swivel means including anchor means for releasably anchoring said cutter and locater means at any desired depth to the wall of the well bore against lateral and longitudinal displacement within the well bore, and
a telescoping joint in said drill string between said drill ship and said swivel means for compensating for vertical movement of said drill ship relative to said well bore.
7. A method for making an outside cut from a floating drill ship on a well pipe having connecting collars and disposed within a well bore, employing an outside cutter mounted on a drill string including a telescoping joint, said method comprising the steps of:
lowering said drill string into the well bore to locate said cutter in surrounding relationship to said pipe, locating said cutter in spaced longitudinal relationship with respect to one of said collars,
rotatably anchoring the drill string at any desired depth within the well bore against lateral and longitudinal displacement,
lowering the drill string to operatively position said telescoping joint,
operating the outside cutter to sever said pipe,
releasing the drill string from its anchored position,
utilizing the drill string to remove the severed pipe from the well bore.
8. The method of claim 7 wherein said cutter is lowered in spaced longitudinal relationship with respect to one of said collars by raising said drill string to contact said collar with an overshot carried by said drill string.
9. The method of claim 7 whereinsaid drill string is rotatably anchored within the well bore by rotating said drill string to the right and lowering to actuate anchor means and swivel means carried by the drill string.
10. The method of claim 7 wherein said outside cutter is operated by rotating said drill string to rotate said cutter and supplying pressurizing fluid to said cutter through said drill string to act on seal means carried by said cutter and sealing between said cutter and said pipe.
11. The method of claim 9 wherein said drill string is released from its anchored position by raising it to release said anchor means.
12. An apparatus for use with a floating drill ship, for cutting and retrieving a pipe having connecting collars and disposed within a well bore, comprising:
a drill string adapted to be suspended from said drill ship,
means for compensating for relative vertical movement between said drill ship and the well bore, a cutter on said drill string having at least one movable knife adapted to engage and cut said pipe,
locater means carried by the drill string for locating and engaging a collar on said pipe to locate said cutter a spaced distance from said collar,
swivel means for rotatably supporting said cutter and locater means within the well bore, and
anchor means on the swivel means for engaging the well wall at any desired depth for releasably anchoring said cutter, locater means and swivel against lateral and longitudinal displacement within the well bore.
13. The apparatus according to claim 12 wherein said cutter is an outside cutter adapted to surroundingly engage said pipe.
14. The apparatus according to claim 13 wherein said cutter is hydraulically actuated.
15. The apparatus according to claim 12 wherein said locater means comprise an overshot.