US3489211A - Method and apparatus for parting subsurface well casing from floating drilling vessels - Google Patents

Description

Jan. 13, 1970 A. w. KAMMERER. JR 3,489,211

METHUD AND APPARATUS FOR PARTING SUBSURFACE WELL CASING FROM FLOATING DRILLING VESSELS Filed Sept. 18, 1967 4 Sheets-Sheet l JANE/V702 .QECHEQ W KQMMEEEE, IQ.

4 TToeA/E 2/.

Jan. l3, 1970 A. w. KAMMIERER. JR I 3,489,211

METHOD AND -APPARATUS FOR PARTING SUBSURFACE WELL CASING FROM FLOATING DRILLING VESSELS f/vvs/vroe. ee/4E2 WHOM/WERE? Je wwm/ MM i. fir roe/va Jan. 13, 1970 A. w. KAMMERER. JR 3,489,211

METHOD AND APPARATUS FOR PARTING SUBSURFACE WELL CASING FROM FLOATING DRILLING VESSELS Filed Sept. 18, 1967 4 Sheets-Sheet 5 IN vew 7'02 .QRCHEQ WKQMMEeE/e, JQ.

1970 A. w. KAMMERER. JR 3,439.

METHOD AND APPARATUS FOR PARTING SUBSURFACE WELL CASING FROM FLOATING DRILLING VESSELS Filed Sept. 18, 1967 4 Sheets-Sheet 4 United States Patent Oflice 3,489,21 l Patented Jan. 13, 1970 3,489,211 METHOD AND APPARATUS FOR PARTING SUB- SURFACE WELL CASING FROM FLOATING DRILLING VESSELS Archer W. Kammerer, Jr., Fullerton, Calif., assignor of one-fifth to Jean K. Lamphere, Fullerton, Calif., and three-fifths to Archer W. Kanunerer, Fullerton, Calif.

Filed Sept. 18, 1967, Ser. No. 668,493 Int. Cl. E21b 33/035, 43/01, 7/12 US. Cl. 166-5 28 Claims ABSTRACT OF THE DISCLOSURE A drilling string extending from a floating vessel or platform and connected through a telescopic joint or bumper sub to an expandable casing parting or milling tool which is secured through a swivel to a releasable anchor. The swivel parts are initially secured against relative rotation, enabling rotation of the drilling string to be transmitted through the bumper sub, parting tool a swivel to the anchor, to expand anchor slips into holding engagement with the well casing and thereby prevent vertical shifting of the parting tool. Torque or rotation of the apparatus then releases the swivel and enables the parting tool to be rotated and actuated to part the casing without turning the anchor, after which the anchor is released to permit longitudinal movement of the parting tool for use in milling away a length of the casing, if desired.

The present invention relates to the performance of cutting operations in subsurface well bores, and more particularly to methods and apparatus for cutting casing or other conduit strings in a well bore located below a body of water.

In a well bore underlying the ocean or other body of water, it is sometimes necessary to sever or mill away casing in the well bore from a floating drilling barge or platform. Wave and wind action causes the barge to move vertically, making it difficult to effect the severing cut at a required depth in the Well bore. In order to locate the casing severing tool in a fixed vertical location in the well bore, it has been secured to a drilling string and lowered in the well bore to the desired location, a marine swivel being disposed in the upper portion of the drilling string and bearing upon a riser or blowout preventer stack located above the ocean floor. The swivel and the riser or blowout preventer stack support the entire weight of the drilling string, which may be thousands of feet in length and correspondingly of great weight, which imposes an undersired high load on the riser or blowout preventer stack. The swivel prevents lowering of the drilling string and severing tool in the event a length of casing is to be milled away following its severing, requiring elevation of the drilling string to remove the swivel, followed by reconnection of the upper portion of the drilling string to the section below the swivel and lowering of the drilling string to relocate the severing or milling tool at the casing cut. Since the cost of operation of floating drilling vessels is very high, the time spent in elevating the drilling string to remove the marine swivel, and then reconnecting drill pipe sections and relowering the tool to its cutting position, entails substantial expense.

The present invention overcomes the above-noted difliculties and disadvantages of the prior devices and mode of operation. It permits the parting of a casing, or similar section in a well bore, form a floating vessel, vertical movement of the parting tool being prevented despite the rise and fall of the floating vessel. The casing severing operation takes place without the need for supporting the drilling string and the riser or blowout preventer, or y other equipment, at the ocean floor. Instead, the parting tool is held in a fixed vertical location by an anchor expanded into engagement with the well casing itself and in the region of the parting tool. If a length of casing is to be cut away, after performance of the casing severing operation, the anchor is easily released and the parting tool used for accomplishing the casing milling operation, without the need for withdrawing or disconnecting any portions of the drilling string. Appropriate rotation of the drilling string, imposition of the required weight on the casing parting and milling tool, andcirculation of fluid for removing the cuttings are all that is necessary in effecting milling away of the casing along a desired length.

This invention possesses many other advantages and has other purposes which may be made more clearly apparent from a consideration of a form and method embodying the invention. This form and method are shown and described in the present specification and in the drawings accompanying and consituting a part. thereof. They will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense.

Referring to the drawings:

FIGURES l to 5, inclusive, are diagrammatic views of apparatus embodying the present invention disposed in a well casing, and in various operative conditions for performing a severing cut in the casing, and for subsequently milling away a length of the well casing;

FIG. 6 is a side elevational view of the apparatus disposed in the well casing, with the parts in position for moving the apparatus downwardly and upwardly within the casing;

FIGS. 7a to 7d are side elevational and longitudinal section views of the combination of apparatus shown in FIGS. 1 to 6, inclusive, FIGS. 7b, 7c and 7d constituting lower continuations of FIGS. 7a, 7b and 7c, respectively, FIGS. 70, 7b, 7c and 7d being taken along the lines 7a7a, 7b7b, 7c--7c, and 7d7d, respectively, of FIG. 6;

FIG. 8 is a longitudinal section of the expanding milling tool corresponding to FIG. 7b, but with the cutters in their expanded position;

FIG. 9 is a quarter sectional view of the anchor shown in FIG. 7d, with its slips anchored against the well casing;

FIG. 10 is a view similar to FIG. 9 disclosing the anchor released from the well casing.

The apparatus illustrated in the drawings is specifically provided for the purpose of severing casing A, or a similar conduit string, disposed in a well bore B at a desired location, and, if required, for continuing to mill away a desired length of easing beginning at the region of severance. More specifically, the apparatus is designed for use in performing a cutting action in a well bore underlying a body of water, the cutting action being undertaken from a vessel (not shown) floating on the water and possessing the usual equipment for drilling a well bore.

As disclosed diagrammatically in FIGS. 1 to 5, inclusive, and in side elevation in FIG. 6, the apparatus is a combination of devices that are known individually. The lower end of a string of drill pipe C is connected to a telescopic joint D through. which torque can be transmitted, known as a bumper sub, which, in turn, is connected to a suitable length of drill collars E having a predetermined desirable weight for use in effecting milling away of a length of easing, the lower end of the drill collars being secured to a milling tool F having expandable cutters 10. The lower portion of the milling tool is attached to a swivel G, which, in turn, is secured to an anchor device H. This combination is lowered from the floating vessel by means of the drilling string C into the wellbore 3 until the cutters of the expanding milling tool are .ocated at the location at which the casing A is to be ;evered.

The specific bumper sub D, expanding milling tool F, ;wivel G, and anchor H are disclosed in the drawings for .llustrative purposes only, and although each of these .tems of equipment will be described in some detail, it is to be understood that other equivalent specific devices :an be used.

The torque transmitting telescopic joint or bumper sub D (FIGS. 6 and 7a) includes an outer tubular member 11 threadedly secured to the lower end of the string of drill pipe C, this outer member being telescoped over an inner tubular member 12 having elongate splines 13 thereon meshing with companion splines 14 on a lower head "15 forming part of the outer tubular member. Leakage of Fluid between the inner and outer tubular members 12, 11 is prevented by a seal ring 16 slidably and sealingly en} gaging the inner wall 17 of the outer tubular member and held in place by being confined between a lower nut 18 threaded on the upper portion of the inner tubular member and bearing against an abutment ring 19 seated on an upwardly facing shoulder 20 on the inner member. The upper end of theseal ring 16 engages a suitable nut 21 threadedly secured to the upper end of the inner tubular member. The degree of telescopic movement of the outer tubular member 11 along the inner tubular member 12 is more than ample to permit the outer tubular member to rise and fall during the making of the severing cutin the casing, the length of travel between a fullycofitracted condition and a fully extended condition of the telescopic joint being, for example, about five feet or ten feet. In the event the outer tubular member 11 moves upwardly to its fullest extent, the upper end 22 of the lower head 15 will engage the ring 19, Downward movement of the outer tubular member relative to the inner tubular member is limited by engagement of the lower end 23 of the lower head with a lower flange 24' on the inner tubular member 12.

, The inner tubular member 12 is threadedly connected to the drill collars E, which may consist of a plurality of interconnected drill collar sections used to provide sufficient weight to the milling tool cutters 10 in effecting a cutting away of the casing after it has been severed. The lowermost drill collar section is threadedly secured to the upper mandrel 25 of the expanding milling tool F, which has an upper pin 26 threadedly connected to the threaded box 27 of the adjacent drill collar section. This mandrel includes an upper kelly or drill stem member 28 slidably splined to the main body 29 of the bit and which has a lower threaded box 30(FIGS. 7b and 7c). The exterior 31 of the lower portion of the kelly 28 is non-circular in shape, being telescopically received in a companion noncircular socket 32 formed in the main bit body 29. The kelly exterior and the socket may be hexagonally shaped to enable the kelly to be moved longitudinally with re spect'to the body 29, while still being capable of transmitting rotary motion and torque to the body; It is to be understood, however, that other non-circular shapes can be used.

The mandrel 25 has a limited range of longitudinal movement within the body, its relative downward movement being determined by engagement of the lower end 33 of the kelly with an'inwardly directed body shoulder 34, and its upward movement being limited by engagement of an external "shoulder or piston portion 35 of the kelly with a cylinder head 36' secured to the body 29 against longitudinal movement with respect thereto. The upper end of the head has a flange 37 engaging an upwardly facing body shoulder 38, the flange being prevented from moving upwardly of the body by split, snap retainer rings 39 fitting in a body groove 40 and overlying the flange 37. An annular guide 41 is releasably secured to the body by a split, snap ring 42 above the retainer rings 39.

The body 29 has a plurality of expansible parts mounted on it, including cutter supporting members 43 pivotally mounted in body slots 44 on-hinge pins 45 suitably secured to the body to prevent their loss therefrom. Each cutter supporting member 43 depends from its hinge pin 45 and carries a milling cutter structure 10 at its lower end, which may be suitably welded, or otherwise attached, to the supporting member.

The cutter supporting members 43 and the cutter structures 10 tend to occupy a retracted position substantially entirely within the confines of the main body 29 of the bit. These cutter supporting members and the cutter structures are expandable outwardly to sever the casing, and also, if desired, to mill it away by operating upon the upper end K of the casing therebelow (see FIGS. 4 and 5 To accomplish the expansion, each cutter supporting member has an inclined expander surface 46 on its inner portion below the hinge pin 45 thattapers in a downward and inward direction. Each expander surface terminates in a lock surface 47 formed on the lock portion 48 of the cutter supporting member. The outward expansion is accomplished by producing relative longitudinal movement between the mandrel 25 and the bit body 29, which will produce relative longitudinal movement between the cutter supporting members 43 and a tubular member 49 of the mandrel.

The tubular member 49 includes a lower portion 50 slidably mounted within a guide bushing 51 mounted in a bridge 52 secured to the body and extending across the body slots 44. This guide bushing 51 is disposed below the lock portions 48 of the cutter supporting members 43. The tubular member 49 extends downwardly of the guide bushing 51 and is adapted to discharge fluid into the well bore B or casing A.

Located initially substantially above the guide bushing 51 and below the hinge pins 45, and in cutter member recesses 53, is a mandrel lock and expander 54 which has outer surfaces 55 adapted to engage the lock surfaces 47. The lock and expander 54 may be formed integrally with the tubular member 49, its upper enlarged boss 56 being piloted within a socket 57 formed in the lower portion of the kelly 28. The enlarged boss 56 on the tubular member engages a downwardly facing shoulder 58 of the kelly, the tubular member being held against this shoulder by a suitable split retainer or lock ring 59 therebelow mounted in the kelly 28.

Drilling mud or other fluid can pass down through the central passage 60 of the kelly or drill stem 28 and into the central passage 61 extending completely through the tubular member 49, this fluid passing through a nozzle 62 of suitable size secured within the lower end of the tubular member passage and discharging into the well casing. Leakage of fluid around the exterior of the tubular member 49 is prevented by a suitable side seal ring 63 mounted in the kelly and engaging the exterior of the boss 56.

Assuming the body 29 of the tool to be elevated relatively along the tubular mandrel 25, the inclined expander surfaces 46 of the cutter supporting members 43 will be shifted upwardly along the lock and expander portion 54 of the tubular members. .During such upward shifting, the cutter supporting members 43'and the cutter structures 10 carried thereby will pivot about the hinge pins 45 and be urged in an outward direction. The upward movement of the body 29 with respect to the tubular mandrel can continue until the cutter structures 10 have been shifted outwardly to their fullest extent, as determined by engagement of stop shoulders 64 on the cutter supporting members with companion shoulders 65 formed on the body on opposite sides of the body slots 44. When such engagement occurs, the lower end 33 of the kelly portion of the tubular mandrel will engage the body shoulder 34, and the lock and expander 54 on the tubular member will be disposed behind and in engagement with the lock portions 48 of the cutter supporting members 43.

Relative longitudinal movement between the tubular mandrel 25 and the body 29 of the tool is accomplished hydraulically in the specific form of apparatus shown in the drawings. The piston or enlarged portion 35 of the drill stem is received Within a counterbore 66 in the upper portion of the body of the tool. This upper portion actually constitutes a cylinder 70 having a cylinder wall extending from the lower shoulder 67 defining the bottom of the counterbore to the cylinder head 36. I

A confined cylinder space 68 is formed between the piston portion 35 of the kelly, the cylindrical periphery of the kelly above the piston, the cylinder 70 and head 36. A suitable packing or side seal ring 71 may be mounted on the piston portion 35, which is adapted to slidably seal against the cylinder wall 66 of the cylinder. Fluid is thereby prevented from passing in a downward direction between the piston and cylinder. Similarly, fluid is prevented from passing in an upward direction out of the annular cylinder space 68 by an inner side seal ring 72 carried by the cylinder head 36 and slidably and sealingly engaging the cylindrical periphery of the kelly above the piston, and also by an outer side seal ring 73 on the head sealingly engaging the cylinder wall 66.

Fluid under pressure in the string of drill pipe C, bumper sub D, drill collars E, and in the tubular mandrel passage 60 can be fed into the cylinder space 68 through one or more side ports 74 establishing communication between the central passage through the kelly and the cylinder space. Such fluid under pressure is developed, as disclosed in the drawings, by virtue of the fact that the area through the lower nozzle 62 is substantially less than the area of the passage 60 through the kelly portion of the mandrel, or because of the fact that the passage 61 through the tubular member of the mandrel is of restricted diameter as compared to the kelly passage 60. As a result, the pumping of drilling mud or other fluid at an adequate rate through the drilling string C and the apparatus results in the building up of a back pressure of fluid in the passage 60, which pressure will then be imposed on the fluid in the cylinder space 68, such fluid under pressure acting upon the cylinder head 36 to urge the body 29 of the tool in an upward direction with respect to the tubular mandrel 25 and secure outward expansion of the cutter supporting members 43 and cutter structures to their fullest extent, as above described.

When the combination of apparatus disclosed has been lowered in the well casing A, with the cutter supporting members 43 and the cutters 10 in their initial retracted position, to the desired point at which the cutters are to sever the well casing, the pumps (not shown) on the floating vessel are started to pump fluid at a sufficient rate through the drill pipe C, bumper sub D, and drill collars E into the mandrel passages 60, 61 and through the lower nozzle 62, building up a back pressure in the kelly passage 60, ports 74 and cylinder space 68, which pressure acts upon the cylinder head 36 to urge the body 29, the cutter supporting members 43 and the cutter structures 10 in an upward direction with respect to the mandrel 25. During such upward movement, the expander surfaces 46 are brought to bear against the lock and expander portion 54 of the mandrel, the cutter structures 10 being urged in an outward direction against the wall of the well casing A. The drill pipe C, bumper sub D, drill collars E and the expanding milling tool F are rotated at the proper speed while fluid is being pumped through the apparatus, the outer or reamer edges of the cutters 10 acting upon the wall of the casing and gradually cutting it away. During this operation, the milling tool body 29 is retained in the same longitudinal position in the well casing A, the inner tubular member 12 of the bumper sub being extended fully downwardly out of the outer tubular member 11. As

the casing is cut away, the hydraulic force acting upon the body 29 raises it and the cutter supporting members 43 and cutter structures 10 to a further extent until the outer edges of the cutters have completely severed the casing. Thereafter, rotation of the drill pipe C, bumper sub D, drill collars E, and the expanding milling tool F continues, so that the outer reaming portions of the cutters continue to mill away the casing and dig into the surrounding formation ntil the cutters 10 have been fully expanded outwar ly to their maximum extent, as determined by engagement of the stop shoulders 64, 65 and the lower end 33 of the kelly portion of the mandrel with the body shoulder 34. With the parts in this position, the lock portion 48 of each cutter supporting member bears against the lock and expander portion 54 of the tubular member 49 to preclude inadvertent partial retraction of the cutter structures from their fully expanded position (FIG. 8).

As stated above, the expanding milling tool F is of a known type, being shown, for example, in United States Patent No. 3,283,834.

The lower threaded :box 30 of the body of the expanding rnilling tool is threadedly secured to the upper pin 76 of an upper su-b or member 77 forming part of the swivel G (FIG. 70). The lower portion 78 of the upper member is enlarged in external diameter and has a counterbore 79 receiving the upper portion 80 of a lower sub 81, this upper portion having an external flange 82 thereon upon which a suitable rollable type of bearing 83 rests, the upper end of the bearing engaging a downwardly facing shoulder 84 of the upper sub. The lower sub or member 81 is retained upwardly within the upper sub or member 77 by a gland 85 engaging the lower side of the flange 82 and which is held in position by a split retainer ring 86 underlying the gland and received within an internal groove 87 in the upper member. A support ring 88 bears against the lower end of the gland 85 and extends within and partially across the retainer ring 86, this support ring being secured to the gland by a plurality of longitudinally extending cap screws 89.

The upper sub 77 is adapted to rotate relative to the lower sub 81, and during such rotation, as well as when the upper sub 77 is stationary, downward forces can be transmitted from the upper sub through the bearing 83 to the lower sub 81. Similarly, upward pulling of the upper sub 77 is transmitted to the flange 82 through the retainer ring 86 and gland 85. Initially, however, relative rotation between the upper and lower subs or members 77, 81 is prevented by one or a plurality of shear screws 90 threaded in the outer member 77 and fitting within companion radial sockets 91 opening through the periphery of the flange 82 of the inner member 81. The shear screws 90 have suflicient strength as to permit the upper and lower members of the swivel to rotate as a unit and transmit substantial torque required for setting the anchor H in the well casing, as described hereinbelow. The transmission of suflicient torque through the shear screws 90 will effect their disruption, whereupon the swivel G becomes operative, permitting rotation of the upper sub 77 with respect to the lower sub 81, while downward forces can be transmitted from the upper sub through the bearing 83 to the lower sub.

The lower end of the lower sub 81 is threadedly secured to a coupling 93 (FIG. 7d), which, in turn, is threadedly attached to the upper end of a central tubular body or mandrel 94 of the anchor H, which is adapted to be set in the well casing A against longitudinal movement therein in both upward and downward directions. The anchor is secured in the well casing by slips 95, and an upper expander structure 96 and a lower expander structure 97 disposed on opposite sides thereof. A single set of circumferentially spaced slips can be anchored against the wall of the well casing A to prevent movement of the anchor apparatus both upwardly and downwardly. Each slip has external wickers or teeth 98 adapted to be embedded in the wall of the well casing, and also an upper inner tapered surface 99 inclined in a downward and inward direction and a lower inner tapered surface 100 nclined in an upward and inward direction. The upper :xpander has a frustoconical tapered surface 101 com- :anion to the tapered surface 99 of the upper ends of he slips, for the purpose of urging the slips laterally outvardly; whereas, the lower expander has a frustoconical apered surface 102 companion to the tapered surface 100 )n the lower portions of the slips and adapted to expand he slips laterally outwardly and to hold them in such )utward position.

Each slip 95 is disposed in an opening or window 103 n a housing or outer tubular member 104 encompassing he body 94 of the tool and its upper and lower expanders F6, 97. The width of each opening 103 conforms to the vidth of each slip; whereas, the length of each opening s greater than the length of each slip. The housing 104 s carried by the body 94 of the tool through a swivel :onnection, which includes a coupling or nut member 105 hreaded on the body of the tool and secured thereto by l screw 106. The swivel further includes a lower shoulder L07 on the upper portion of the housing engaging the ower end of the coupling 105 to prevent upward movement of the housing 104 along the body of the tool, lownward movement of the housing relative to the body )f the tool being prevented by a split snap ring 108 in the rousing and engaging an upper surface of the nut or :oupling flange.

The body 94 of the tool is provided with an external lpper left-hand thread 109 and with an external lower 'ight-hand thread 110. The upper portion of the upper eft-hand thread may be employed for securing the couvling 105 and housing 104 to the body of the tool. The eft-hand thread 109 engages a companion internal leftland thread 111 on the upper expander 96, the upper :xpander initially occupying an upper position on the body if the tool, determined by engagement of a rotational top pin 112 on the upper portion of the upper expander, vith a companion stop pin 113 secured to and depending rom the coupling 105.

The external right-hand thread 110 meshes with a comanion internal right-hand thread 114 on a lower sleeve .15 of the lower expander structure 97, which is en- :ompassed by an outer expander sleeve portion 116 of the tructure and which is secured thereto by one or a pluality of shear pins 117, so that the outer expander memver 116 and sleeve 115 normally coact and function as unitary lower expander member 97. Both the upper 11d lower expander members 96, 97 are spaced apart suficiently to be out of operative engagement with the comuaniOn upper and lower tapered surfaces 99, 100 of the lips, which can occupy a retracted position relative to he body 94 of the tool and its housing 104. Retraction vi the slips is insured by a plurality of helical tension prings (not shown) and extending between and secured o the opposite sides of the slips, as shown in United States 'atent No. 3,077,933, which more particularly discloses he anchor apparatus H illustrated in the drawings. These prings normally tend to pull the slips 95 inwardly to heir retracted position, but will stretch or expand to allow he upper and lower expanders 96, 97 to shift the slips utwardly into anchoring engagement with the wall of be well casing A.

The slips 95 are expanded outwardly against the well asing by rotating the drilling string C and all of the ,pparatus D, E, F, G, connected thereto and the body or mandrel 94 to the right, while preventing the upper and ower expanders 96, 97 and the slips 95 themselves from otating. To prevent rotation of the expanders and slips, |utwardly bowed circumferentially spaced leaf springs .20 are mounted on the exterior of the housing 104, being ecured thereto by screws 121 which extend inwardly into :eys 122 within the housing disposed in longitudinal keyvays 123 in the upper expander 96. The lower ends 124 f the springs are free and are disposed in the lower lortions of longitudinal grooves 125 in the exterior of he housing, being slidable along the base of the grooves.

The intermediate portions engage the wall of the well casing A for the purpose of resisting rotation of the housing 104. In view of the key and keyway connection 122, 123 of the housing with the upper expander 96, rotation of the latter is also resisted by the friction drag springs 120. Rotation of the lower expander structure 97 is also resisted by a key and keyway or slot connection. As disclosed, pins or screws 126 are secured to the lower expander member 116, extending within longitudinal slots 127 in the housing. When the lower expander 97 is in its initial position in which the slips are retracted, the pins or screws 126 are located in the lower portions of the slots 127.

In the use of the anchor apparatus H, the upper expander 96 is disposed initially in its uppermost position illustrated in FIG. 7d, with the rotational stop pins 112, 113 in engagement. The lower expander structure 97 is disposed in its lowermost position along the body 94 of the tool. When the anchor apparatus has been lowered in the well casing to the desired location therein at which the apparatus is to be set, the drilling string C and the several devices connected thereto are rotated to the right, as through the use of hand tongs (not shown) on the floating drilling vessel. The friction drag springs 120 prevent the housing 104, upper and lower expanders 96, 97, and slips 95 therebetween from turning, because of the resistance afforded by the springs against the wall of the casing. However, the nut or coupling can turn with the body since its connection with the upper portion of the housing is a swivel one, the coupling turning between the housing shoulder 107 and the split snap or coupling ring 108. Rotation of the body of the tool relative to the expanders results in the upper expander 96 threading relatively downwardly along the body, and the lower expander structure 97 threading relatively upwardly along the body of the tool, the upper and lower expanders engaging the upper and lower tapered surfaces 101, 102 of the slips and shifting the latter radially outwardly through the housing openings 103 into engagement with the wall of the well casing A.

After the slips 95 contact the casing, a strain may be placed on the drilling string C, which will be transmitted through the several items of apparatus D, E, F, 6 connected in series to the mandrel 94, and right-hand torque is then applied to the drilling string. Downweight is then imposed on the drilling string and through the apparatus connected thereto to the mandrel, the right-hand torque being maintained thereon. The alternate pulling of a strain and the setting down of weight on the drilling string and the apparatus connected thereto, with torque applied, insure that all play or lost motion has been removed from the anchor apparatus H so that the upper expander 96 is firmly wedged behind the upper portions of the slips 95 and the lower expander 97 is firmly wedged behind the lower portions of the slips (FIG. 9). Since the anchor H is firmly secured to the well casing, the body 29 of the expanding milling tool and its cutters 10 will be definitely located in the casing string and their vertical movement therein prevented.

In order to release the anchor H from the casing, the drilling string C is pulled upwardly sufficiently, the upward strain being transmitted through the bumper sub D, drill collars E, expanding milling tool F and swivel G to the body or mandrel 94 of the anchor, and from the latter to the lower expander sleeve 115, passing through the shear pins 117 to the lower expander member 116 and then to the slips and into the well casing. When the strain exceeds the shear value of the pins 117 securing the outer expander portion 116 to the inner expander sleeve 115, the shear pins are disrupted or sheared, which will then allow the body 94 to move upwardly, carrying the upper expander 96 upwardly of the slips 95, and the lower sleeve upwardly within the lower expander member 116. Removal of the upper expander 96 from its wedging position behind the slips effects the release of the wedgof the springs 120 frictionally I ing force on the slips, and also allows the lower expander member 116 to drop downwardly along the housing, such as illustrated in FIG. 10, the springs (not shown) then pulling the slips 95 laterally inwardly from the casing A or toward a releasing position. The drilling string C and all of the apparatus attached thereto can now be elevated or lowered, as desired.

The method of using the apparatus in severing the casing, and, if desired, of milling away a length of the casing after the severing out has been completed, is illustrated diagrammatically in FIGS. 1 to 5, inclusive, of the drawings. As shown in FIG. 1, the anchor H, with its parts in their initial condition disclosed in FIG. 7d, is secured through the coupling 93 to the swivel G, the upper and lower subs 77, 81 of which cannot rotate relative to one another because of the interconnecting shear screws 90. The upper portion 77 of the swivel is connected to the body 29 of the expanding milling tool F, the mandrel 25 of which is secured to the drill collars E, which usually have a predetermined weight required for forcing the expanded cutters 10 downwardly against the severed end K of the casing, and which, for example, may be about 10,000 lbs. The upper end of the uppermost drill collar is connected to the inner tubular member 12 of the bumper sub D, the outer tubular member 11 of which is attached to the drill pipe C that extends upwardly to the usual rotary equipment and drawworks (not shown) mounted on the vessel floating in the body of water overlying the well bore B. The combination of apparatus C, D, E, F, G, H is lowered in the well casing, at which time the weight of the equipment will pull the expanding mill body 29 in a downward position along its mandrel 25, the inner tubular member 12 of the bumper sub being expanded to its fullest extent from the outer tubular member 11 of the bumper sub D.

The severing cut is preferably made to one side of a casing coupling. In order to find a casing coupling in the region of the cut, fluid can be pumped down through the drilling string and will pass through the expanding mill, building up a pressure in the cylinder space 68 and elevating the body 29 along the mandrel to cause the cutter members 10 to expand outwardly against the wall of the casing. The lowering of the apparatus in the casing will cause the milling cutters to shift into the first casing coupling therebelow, informing the operator, by the loss of weight on the drilling string, that the casing coupling has been entered. The pumping of fluid is then discontinued, and the string of apparatus elevated by elevating the drilling string C to the location above the casing coupling at which the severing cut is to be made. The drilling string is then turned to the right, the right-hand turning effort torque being transmitted through the bumper sub D to the drill collars E and through the expanding milling tool mandrel 25 to the body 29 of the tool, from where the turning effort is transmitted through the upper sub 77 of the swivel G through its shear screws 90 to the lower sub 81, and then to the body or mandrel 94 of the anchor H. Rotation is continued for the required number of turns of the anchor body 94, which, for example, may be about eight turns, to shift the upper and lower expanders 96, 97 behind the slips 95 and expand the latter firmly into anchoring engagement with the wall of the well casing, in the manner described above (FIG. 2). After the slips have been firmly anchored, an increase in the turning effort applied through the swivel G will shear the screws 90 and enable the upper member 77 of the swivel to turn relative to its lower portion 81, which means that the expanding mill F, drill collars E, bumper sub D and drilling string C can then be rotated without turning the anchor H.

The drilling string C is then lowered or slacked off until the bumper sub D is in its collapsed position, that is, its lower head 15 is adjacent to the lower flange 24 of the inner tubular member 12, which will prevent the up and down movement of the floating vessel and of the drill pipe C from being transmitted to the inner tubular member 12. The drilling string is then rotated, the rotation bemg transmitted through the bumper sub D and drill collars E to the mandrel 25 and the body 29 of the tool, to rotate the milling cutters 10. During such rotation, and even 111 the absence of any substantial pressure built up in the expanding milling tool as a result of pumping fluid therethrough, the weight of the drill collars B will urge the mandrel downwardly and cause its expander 54 to bear against the expander surfaces 46 on the supportlng members 43 and urge the milling cutters 10 outwardly. The milling tool is rotated at the proper speed, which, for example, may be about 80 to 100 r.p.m., the cutters penetrating the casing A and cutting it away, the cutters remalning at the same location in the well casing. Rotatlon continues and the fluid circulation pressure increased to the maximum practical extent until the expanding milling tool F no longer requires any significant torque to effect its rotation, which is indicative of the fact that the milling cutters 10 have been expanded outwardly to their fullest extent and have completely severed the casing (FIG. 3).

The pumps are now stopped and a pull taken on the drilling string C, bumper sub D (which will expand to its fullest extent), drill collars E and mandrel 25 to shift the latter upwardly within the body 29, and then exert an upward pull on the body 29, which is transmitted through the swivel G to the anchor mandrel 94 and its inner sleeve 115. When this pull has reached the shear value of the pins 117, which, for example, may be about 25,000 lbs., they are sheared, which then permits the anchor mandrel or body 94 to move upwardly and elevate the upper expander 96 from the slips and permit the lower expander member 116 to drop downwardly from the slips, the slips then being pulled inwardly to their retracted position, as disclosed in FIG. 10. In other words, the anchor H has now been rendered inoperative.

As a result of the upward pull on the string of tools, the cutters 10 will have returned to their retracted position within the confines of the body 29 of the expanding milling tool F (FIG. 4). Accordingly, the pumps are started again and fluid circulated through the drilling string C and all of the apparatus connected thereto, the combination of apparatus being rotated. The pump pressure built up within the cylinder space 68 will reelevate the body 29 of the tool along its mandrel 25 and urge the cutters 10 outwardly. When they come opposite the cut R (FIG. 4), they will expand out again to their fullest extent and then come to rest upon the severed end K of the casing A. The drilling string C can then be lowered slightly to position the outer tubular member 11 of the bumper sub D midway along the inner tubular member 12 and allow the entire weight of the drill collars E to be imposed upon the mandrel 25, the lower end 33 of which then engages the body shoulder 34 so as to transmit the weight of the drill collars, which, as stated above, may be about 10,000 lbs., to the cutters 10 and force them against the upwardly facing severed end K of the casing. The drilling string is rotated at the proper milling speed while fluid is circulated down through the string of tools at the required flow rate and pressure, the cutters 10 progressively milling away the casing section to the desired extent (FIG. 5). The bumper sub or telescopic joint D prevents the vertical movement of the drilling vessel from interfering with the milling action.

After the casing has been milled away to the required extent, the pumps are stopped and rotation discontinued, the elevation of the drilling string elevating the mandrel 25 back to the position shown in FIG. 7b, which permits the milling cutters 10 to shift inwardly to their retracted condition. The drilling string C can now be elevated to elevate the entire interconnected series of tools D, E, F, G, H in the well casing to the floating vessel.

It is, accordingly, apparent that a method and apparatus have been provided which is capable of severing the casing and, if desired, of milling it away along a require ,ength, without the necessity for imposing substantially he entire weight of the drilling string on any other equipnent associated with the well bore, such as risers or blow- )ut preventers mounted above the floor of the ocean. The :utters 10 of the parting tool are located appropriately and held in proper position by use of the subsurface anchor H, and such anchor is released to permit the casing be milled away without the necessity for removing any 3f the apparatus from the well bore, or for disconnecting any portions of the drilling string C. As a result, the disadvantages of prior devices are overcome by avoiding the imposition of weight on equipment externally of the well bore, and in effecting savings in time in accomplishing the desired result of parting the casing and milling it away to a required length.

I claim:

1. A method of severing casing disposed in a well bore, which comprises lowering an anchor apparatus and a severing tool having an expandable cutter in the casing by means of a drilling string, anchoring said anchor apparatus in the casing to locate said cutter at the desired severance point of the casing, operating said severing tool to expand its cutter against the casing and sever the same, releasing said anchor apparatus from the casing to permit longitudinal movement of the anchor apparatus and severing tool in the casing, and then moving said severing tool and released anchor apparatus longitudinally in the casing with said cutter expanded to mill away a portion of the casing.

2. A method of severing casing disposed in a well bore, which comprises providing a drilling string with a severing tool connected thereto and an anchor apparatus below and connected to the severing tool, said severing tool having an expandable cutter and said anchor apparatus having slips, lowering the drilling string, severing tool and anchor apparatus in the casing to locate the cutter at the desired severance point in the casing, expanding the slips against the casing to anchor the anchor apparatus in the casing and retain the cutter at the severance point, operating the severing tool to expand its cutter against the casing and sever the same, and releasing the slips from the casing to permit the drilling string to move the severing tool and anchor apapratus in the well casing, and then moving said severing tool and released anchor apparatus longitudinally in the casing with said cutter expanded to mill away a portion of the casing.

3. A method as defined in claim 1, in which the anchor apparatus is anchored to the casing by manipulation of the drilling string, the severing tool severing the casing by rotating the drilling string and severing tool without rotating the anchor apparatus, the anchor apparatus being released from the casing by manipulating the drilling string.

4. A method as defined in claim 1, in which the anchor apparatus is anchored to the casing by rotating the drilling string and without moving the drilling string longitudinally, the severing tool severing the casing by rotating the drilling string and severing tool without rotating the anchor apparatus, the anchor apparatus being released from the casing by longitudinal movement of the drilling string.

5. A method as defined in claim 2, in which the slips are expanded against the casing by manipulating the drilling string, the severing tool severing the casing by rotating the drilling string andsevering tool without rotating the anchor apparatus, the slips being released from the casing by manipulating the drilling string.

6. A method as defined in claim 2, in which the slips are expanded against the casing in response to rotation of the drilling string and without moving the drilling string longitudinally, the severing tool severing the casing by rotating the drilling string and severing tool without rotating the anchor apparatus, the slips being released from the casing by longitudinal movement of the drilling string.

7. A method as defined in claim 1, in which the anchor apparatus is connected to the severing tool through a swivel, the severing tool being rotated to sever the casing after anchoring of the anchor apparatus in the casing without rotating the anchor apparatus.

8. A method as defined in claim 1, in which the anchor apparatus is connected to the severing tool through a swivel initially retained in inoperative condition, the anchor apparatus being anchored to the casing by rotation of the drilling string transmitted through the severing tool and inoperative swivel to the anchor apparatus, releasing the swivel to render it operative following anchoring of the anchor apparatus to the casing, the severing tool severing the casing by rotating the drilling string and severing tool without rotating the anchor apparatus, the anchor apparatus being released from the casing by manipulating the drilling string, and expanding said severing tool cutter while said anchor apparatus remains released from the casing.

9. A method as defined in claim 2, in which the anchor apparatus is connected to the severing tool through a swivel, the severing tool being rotated to sever the casing after expansion of the slips against the casing and without rotating the anchor apparatus.

10. A method as defined in claim 2, in which the anchor apparatus is connected to the severing, tool through a swivel initially retained in inoperative condition, the slips being expanded against the casing by rotation of the drilling string transmitted through the severing tool and inoperative swivel to the anchor apparatus, releasing the swivel to render it operative following expansion of the slips against the casing, the severing tool severing the casing by rotating the drilling string and severing tool without rotating the anchor apparatus, the slips being released from the casing by manipulating the drilling string, and expanding said severing tool cutter while said slips remain released from the casing.

11. A method as defined in claim 1; and said severing tool being operated to mill away a length of easing, commencing with the point of severance, after release of the anchor apparatus in the casing.

12. A method as defined in claim 2; and said severing tool being operated to mill away a length of easing, commencing with the point of severance, after release of the anchor apparatus in the casing.

13. A method as defined in claim 2, in which the slips are expanded against the casing in response'to rotation of the drilling string, the severing tool severing the casing by rotating the drilling string and severing tool without rotating the anchor apparatus, the slips being released from the casing by longitudinal movement of the drilling string; and said severing tool being operated to mill away a length of casing, commencing with the point of severance, after release of the slips from the casing.

14. A method as defined in claim 2, in which the anchor apparatus is connected to the severing tool through a swivel initially retained in inoperative condition, the slips being expanded against the casing by rotation of the drilling string transmitted through the severing tool and inoperative swivel to the anchor apparatus, releasing the swivel to render it operative following expansion of the slips against the casing, the severing tool severing the casing by rotating the drilling string and severing tool without rotating the anchor apparatus, the slips being released from the casing by manipulating the drilling string; and said severing tool being operated to mill away a length of casing, commencing with the point of severance, after release of the slips from the casing. I

15. A method of severing casing disposed in a well bore underlying a body of water from a vessel floating in the body of water, which comprises lowering an anchor apparatus and a severing tool having an expandable cutter in the casing by means of a drilling string embodying a torque transmitting telescopic joint above the severing tool, anchoring said anchor apparatus in the easing to locate said cutter at the desired severance point in the casing, operating said severing tool to expand its cutter against the casing and sever the same, releasing said anchor apparatus from the casing to permit longitudinal movement of the anchor apparatus and severing tool inthe casing, and then moving said severing tool and released anchor apparatus longitudinally in the easing with said cutter expanded to mill away a portion of the casing. v I

16. A method as defined in claim 15, in which the anchor apparatus is connected to the severing tool through a swivel initially retained in inoperative condition, the anchor apparatus being anchored to the casing by rotation of the drilling string transmitted through the telescopic joint, severing tool and inoperative swivel to the anchor apparatus, releasing the swivel to render it ,operative following anchoring of the anchor apparatus to the casing, the severing tool severing the casing by rotating the drilling string, telescopic joint and severing tool without rotating the anchor apparatus, the anchor apparatus being released from the casing by manipulating the drilling string.

17. A method as defined in claim 15, in which the anchor apparatus is connected to the severing tool through a swivel initially retained in inoperative condition, the anchor apparatus being anchoredto the casing by rotation of the drilling string transmitted through the telescopic joint, severing tool and inoperative swivel to the anchor apparatus, releasing the swivel to render it operative following anchoring of the anchor apparatus to the casing, the severing tool severing the casing by rotating the drilling string, telescopic joint and severing tool without rotating the anchor apparatus, the anchor apparatus being released from the casing by manipulating the drilling string, said severing tool being operated to mill away a length of casing, commencing with the point of severance, after release of the anchor apparatus in the casing.

18. A method of severing casing disposed in a well bore underlying a body of water from a vessel floating in the body of water, which comprises providing a drilling string with a torque transmitting telescopic joint connected thereto which is connected to a severing tool therebelow, an anchor apparatus being connected to and below the severing tool, said severing tool having an expandable cutter and said anchor apparatus having slips, lowering the drilling string, telescopic joint, severing tool and anchor apparatus in the casing to locate the cutter at the desired severance point in the casing, expanding the slips against the casing to anchor the anchor apparatus in the casing and retain the cutter at the severance point, operating the severing tool to expand its cutter against the casing and sever the same, releasing the slips from the casing to permit the drilling string to move the severing tool and anchor apparatus in the well casing, and then moving said severing tool and released anchor apparatus longitudinally in the casing with said cutter expanded to mill away a portion of the casing.

19. A method as defined in claim 18, in which the anchor apparatus is connected to the, severing tool through a swivel initially retained in inomrative condition, the slips being expanded against the casing by rotation of the drilling string transmitted through the telescopic joint, severing tool and inoperative swivel to the anchor apparatus, releasing the swivel to render it operative following expansion of the slips against the casing, the severing tool severing the casing by rotating the drilling string, telescopic joint and severing tool without rotating the anchor apparatus, the slips being released from the casing by manipulating the drilling string.

20. A method as defined in claim 18, in which the anchor apparatus is connected to the severing tool through a swivel initially retained in inoperative condition, the slips being expanded against the casing by rotation of the drilling string transmitted through the telescopic joint, severing tool and inoperative swivel to the anchor apparatus, releasing the swivel to render it operative 01- lowing expansion of the slips against the casing, the severing tool severing the casing by rotating the drilling string, telescopic joint and severing tool without rotating the anchor apparatus, the slips being released from the casing by manipulating the drilling string; said severing tool being operated to mill away a lengthof casing, commencing with the point of severance, after release of the slips from the casing.

21. In apparatus for severing casing disposed in a well bore: a severing tool having an expandable cutter and adapted for connection to a drilling string for lowering in the casing; anchor apparatus connected to said severing tool and having initially retracted means expandable against the casing to anchor the anchor apparatus therein; means for expanding said initially retracted means against the casing; means for expanding said cutter against the casing to sever the same after expansion of said initially retracted means against the casing; means for releasing said initially retracted means for the casing, said severing tool and anchor apparatus being movable as a unit in the well bore after release of said initially retracted means and with said cutter expanded for cutting the casing.

22. In apparatus as defined in claim 21; said means for expanding said intially retracted means against the casing being responsive to manipulation of the drilling string; said means for releasing said initially retracted means from the casing being responsive to manipulation of the drilling string.

23. In apparatus as defined in claim 21; said means for expanding said initially retracted means against the casing being responsive to rotation of the drilling string and without moving the drilling string longitudinally; said means for releasing said initially retracted means from the casing being responsive to longitudinal movement of the drilling string,

24. In apparatus as defined in claim 1; means including a swivel interconnecting said severing tool and anchor apparatus, said swivel having relatively rotatable members permitting rotation of said severing tool without rotating said anchor apparatus; releasable means connecting said relatively rotatable members to prevent their relative rotation and retain said swivel in inoperative condition; and means for releasing said releasable means.

25. In apparatus as defined in claim 21; means including a swivel interconnecting said severing tool and anchor apparatus, said swivel having relatively rotatable members permitting rotation of said severing tool without rotating said anchor apparatus; releasable means connecting said relatively rotatable members to prevent their relative rotation and retain said swivel in inoperative condition; means for releasing said releasable means; said means for expanding said initially retracted means against the easing being responsive to rotation of the drilling string transmitted to said anchor apparatus through said severing tool and swivel when in inoperative condition; said means for releasing said initially retracted means from the casing being responsive to longitudinal movement of the drilling string.

26. In apparatus as defined in claim 21; a torque transmitting telescopic joint above and connected to said severing tool.

27. In apparatus as defined in claim 21; a torque transmitting telescopic joint above and connected to said severing tool; means including a swivel interconnecting said severing tool and anchor apparatus, said swivel having relatively rotatable members permitting rotation of said telescopic joint and severing tool without rotating said anchor apparatus; releasable means connecting said relatively rotatable members to prevent their relative rotation and retain said swivel in inoperative condition; and means for releasing said releasable means.

28. In apparatus as defined in claim 21; a torque transmitting telescopic joint above and connected to said severing tool; means including a swivel interconnecting said severing tool and anchor apparatus, said swivel having relatively rotatable members permitting rotation of said 15 v telescopic joint and severing tool without rotating said anchor apparatus; releasable means connecting said relatively rotatable members to prevent their relative rotation and retain said swivel in inoperative condition; means for releasing said releasable means; said means for expanding said initially retracted means against the casing being responsive to rotation of the drilling string transmitted to said anchor apparatus. through saidtelescopic joint, severing tool and swivel when in inoperative condition; said means for releasing said initially retracted means from the casing being responsive to longitudinal movement of the drilling string.

10 ERNEST R.

References Cited UNITED STATES PATENTS 11/1938 Osmun 166-55 .8 9/1940 Ellis res-55,8 1/1950 Patrick 16 65 5.7 5/1960 Kinley et a1, 285 '3 2/1963 Bigelow 166'217 7/1967 "Thomas 166-553 X PURSER, Primary Examiner U. S. c1. X.R.

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