GB2246585A

GB2246585A - Hydraulically set anchor for well tools

Info

Publication number: GB2246585A
Application number: GB9111588A
Authority: GB
Inventors: Thomas F Bailey; John E Campbell
Original assignee: Masx Energy Services Group Inc
Current assignee: Masx Energy Services Group Inc
Priority date: 1990-07-31
Filing date: 1991-05-30
Publication date: 1992-02-05
Anticipated expiration: 2011-05-30
Also published as: CA2047588A1; NO912093D0; FR2665724A1; DE4125325A1; DE4125325C2; GB9111588D0; GB2246585B; NO912093L; JPH04261997A

Abstract

A hydraulically set anchor for setting well tools may be connected to the lower end of the well tool or a running string for setting within a cased well bore. The anchor (10) (Figure 1) includes a mandrel (20) with a fluid passageway (32) to supply hydraulic fluid to a piston assembly (38). The piston assembly engages a slip assembly (52) of the anchor used to set the tool. The slip assembly includes a movable upper slip cone (58) which cooperates with slip elements (54) to set the elements into the casing. An interlock assembly (72) associated with the upper cone and the mandrel prevents release of the slip assembly. The slip cone has a shallow angle in relation to the slip elements to facilitate secure setting under minimum hydraulic pressure. <IMAGE>

Description

HYDRAULICALLY SET ANCHOR FOR WELL TOOLS

Background Of The Invention

1. Field of the Invention

This invention relates to anchors for setting well tools in a well and, in particular, to a hydraulically set anchor for use in a whipstock assembly to provide sufficient anchorage to facilitate kick-off from the primary well bore.

II. Description of the Prior Art

Packers and anchors are typically used in well bores to seal off sections of a well andlor to provide support structure for well tools in the production process. Deviating tools, whipstocks, perforating tools, etc. are examples of tools which employ an anchor or packer. In many instances, the anchor/packer is run into the well and set with one trip of the running string and the particular device engaged with the anchor/packer using a second trip of the running string. With the tool supported against thb anchor/packer, the particular operation can be conducted.

More recently, in order to reduce production costs, the tool has been combined with the anchor/packer thereby eliminating one trip of the running string. Consequently, the anchorlpacker is set in the well using mechanical or hydraulic means extending through the well tool after which the tool is engaged to carry out the operation. Once the operation is completed the anchor/packer is typically abandoned with the well.

In the prior known hydraulically set anchor/packer, the hydraulic pressure may have to be maintained in order to prevent release of the tool. As a result, mechanically set tools are typically used in one-trip combination assemblies t since the mechanical set can be maintained following disconnection of the production tool. However, mechanically set anchorlpackers are unreliable in high pressure wells because of the extreme setting forces required which cannot be achieved in such tools. Moreover, it has been found that in many applications, the well bore does not need to be sealed-off by packing elements.

Summary Of The Present Invention

The present invention overcomes the disadvantages of the prior known setting tools by providing a hydraulically set anchor which can be attached to various well tools to provide a supporting surface for continued operations. The anchor of the present invention is adapted to be securely set in the cased well under a minimum of hydraulic pressure as a result of the shallow angle between the slip cones and the associated slip elements.

The hydraulically set anchor of the present invention includes an adapter sub for connection to the production tool and which is joined to a mandrel having a partial axial bore forming a fluid passageway. The fluid passageway communicates with a cylinder formed by the annulus surrounding the mandrel within which is movably disposed a piston assembly. The piston assembly engages the movable upper slip cone of the anchoring slip assembly. The lower slip cone is stationary and is secured to the lower end sub of the anchor. The slip elements are circumferentially spaced and extend between the movable upper slip cone and the lower slip cone. The shallow angle between the slips and the slip cones facilitates secure engagement of the slips with the casing. The forces generated by the hydraulic pressure acting on the inner piston of the tool creates a higher setting force which cannot be achieved by prior known mechanically set anchors. Moreover. the 2 1 i i i i i 1 4 1 i 1 i i i i 1 i i 1 i t mechanical f orce required to shear the bolts of the tool adds to the hydraulic force to set the anchor.

An interlock assembly maintains the set position of the slip assembly with respect to the casing. In the preferred embodiments, the interlock assembly is associated with the movable upper slip cone and the mandrel such that as the upper slip cone travels along the mandrel the position will be maintained therealong. Accordingly, the slip assembly can be locked at any position facilitating anchoring to various casing diameters.

Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings.

Brief Description Of The Drawings

The present invention will be more fully understood by reference to the following detailed description of a preferred embodiment of the present invention when read in conjunction with the accompanying drawing, in which like reference characters refer to like parts throughout the views and in which:

FIGURE 1 is a cross-sectional perspective of a f irst embodiment of the anchor of the present invention as it is run into the cased well bore; FIGURE 2 is a cross-sectional perspective of the first anchor set within a well casing, the anchor being shown set in two different diameter casings; FIGURE 3 is an enlarged perspective of the interlock assembly of the first embodiment of the present invention; FIGURE 4 is an enlarged perspective of the interlock assembly of a second embodiment of the present invention; FIGURE 5 is a cross-sectional perspective of a second embodiment of the anchor of the present invention; 3 r FIGURE 6 is a cross-sectional view of a well bore with a whipstock assembly incorporating the anchor of the present invention being run into the well; and FIGURE 7 is a cross-sectional view of a well bore with a whipstock assembly set therein using the anchor of the present invention.

Detailed Description Of A Preferred Embodiment Of The Present Invention

Referring to the drawings, there are shown preferred embodiments of a hydraulically set anchor 10 adapted to be set within a cased well bore 12 for anchoring various well tools including whipstocks for kicking off in a different direction from the well bore 12 (Figs. 6 and 7). The anchor 10 may be run into the cased well bore 12 in conjunction with the well tool for single trip operations or may be separately run into the hole using a running tool. The whipstock may be attached to a mill, a bit or a separate running tool. The construction and configuration of the anchor 10 facilitates secure setting thereof under hydraulic fluid pressure supplied to the anchor 10 as will be subsequently described.

Referring now to the embodiment of Figures 1 through 3, the anchor 10 is adapted to be selectively connected to a well tool, such as a whipstock or running tool, using an adapter sub 14 having a box connection 16. The sub 14 includes an axial fluid passageway 18 through which the hydraulic setting fluid is supplied. Matingly received by and connected to the sub 14 is an inner mandrel 20 which extends substantially the length of the anchor 10. The mandrel 20 is connected to the adapter sub by a threaded connection 22. The downhole end of the mandrel 20 is connected to a nose sub 24 by threaded connection 26. In this embodiment, the nose sub 24. f orms a part of the lower 4 1 1 i slip cone although the sub 24 may he formed separately from the lower slip cone as shown in Figure 5. In a pref erred embodiment, the mandrel 20 comprises an upper section 28 and a lower section 30 although the mandrel 20 may be integrally formed.

The mandrel 20 includes a fluid passageway 32 formed by a partial axial bore 34 and a lateral bore 36 to supply hydraulic fluid to a piston cylinder 38. The cylinder 38 comprises an annulus formed around the mandrel 20 and within an outer wall 40 which extends from the adapter sub 14. Accordingly, the adapter sub 14 forms the uphole end of the cylinder 38 while the downhole end of the cylinder 38 is open to allow a piston assembly 42 to extend from within the cylinder 38. The piston assembly 42 also has an annular configuration and is slidably received within the cylinder 38. Movement of the piston assembly 42 is effected by increased hydraulic pressure within the cylinder 38 uphole of piston assembly 42 which is supplied through the fluid passageway 32 as will be subsequently described. The piston assembly 42 preferably includes an annular piston head 44 sealingly received within the cylinder 38 so as to be affected by the hydraulic pressure and a piston rod 46 extending from the piston head 44-. O-ring seals 48 carried by the piston head 44 prevent fluid leakage past the piston assembly 42. In a preferred embodiment, the piston rod 46 abuts against the piston head 44 and is thereby affected by the sliding movement of the piston head 44. However, the piston rod 46 may be secured to or integrally formed with the piston head 44. The downhole end of the piston rod 46 preferably includes a port 50 to allow fluid flow within the chamber 38 to flow therefrom as the piston assembly 42 moves within the chamber 38.

The downhole end of the piston rod 46 engages a slip assembly 52 of the anchor 10, specifically upper slip r elements 54 of the slip assembly 52. The slip assembly 52 is mounted to the mandrel 20 and also includes lower slip elements 56 and a double slip cone 58. In a preferred embodiment, the upper slip elements 54 are movable in response to extension of the piston rod 46 thereby driving the slip elements 54 radially outwardly into anchoring engagement with the casing 12. The upper slip elements 54 are initially locked against movement by shear screws 60 extending through a housing locking nut 59 into a locking sleeve 61 mounted to the mandrel 20 thereby preventing travel of the upper slip elements 54 until a predetermined hydraulic pressure is attained. In a first embodiment, an anti-rotation key 62 is disposed between the slip cone 58 and the mandrel 20. The key 62 is received within longitudinal slots 64 in the mandrel 20 to prevent rotation of the slip assembly 52 relative to the mandrel 20.

The movable slip elements 54 and the fixed lower slip elements 56 include interface surfaces 68 which cooperate with the sloped surfaces 70 of the slip cone 52 to drive the elements radially outwardly. The shallow angle of the interface surfaces 68 facilitates secure setting of the slip assembly 52 under a minimum of hydraulic fluid pressure. In a preferred embodiment, the slope of the interface surfaces 68 is less than 20 degrees and preferably 10 degrees. As a result, a simple slip assembly utilizing a single movable slip cone is sufficient to securely anchor the device. Moreover, the shallow slope of the interface allows the anchor 10 to be utilized in different casing diameters as shown in Fig 2 where the anchor 10 is set in two dif f erent casings 12.

Referring now to Fig. 1-3, as the slip assembly 52 is set, interlock means 72 are provided to prevent retraction of the upper elements cone 54 and release of the slip assembly 52 once hydraulic pressure is reduced or 6 i i 1 1 1 1 f eliminated. As best shown in Fig. 3, the interlock means 72 comprises a locking nut 74 having a first ratchet surface 76 which cooperates with a ratchet surf ace 78 on the locking housing 59 and a second ratchet surface 80 which cooperates with a ratchet surface 82 on the mandrel 20. The mandrel ratchet surface 82 extends a substantial length beneath the locking housing 59 such that contact is maintained between the locking nut 74 and the mandrel 20 as the locking housing 59 and the upper slip elements 54 moves towards the slip cone 58. The ratchet surfaces are configured to allow movement of the locking housing 59 and the upper slip elements 54 in a first downhole direction but prevent movement in a second direction. The ratchet surfaces 80 and 82 have smaller teeth to facilitate movement in the first direction while the teeth of the ratchet surfaces 76 and 78 are larger to allow movement only under extreme pressures. Accordingly, once the slip assembly 52 has been set, the hydraulic pressure can be eliminated and the well tool detached without causing release of the slip assembly. The position of the double slip cone 58 is maintained through a series of shear screws 90 which extend into the mandrel 20. The slip cone 58 includes an upper cone section 92 and a lower cone section 94 which cooperate with the upper slips 54 and lower slips 56, respectively. The lower cone section 94 preferably includes at least one spline or keyway 96 to allow the cone 58 to travel longitudinally along the key 62 in order to expand the lower slip elements 56 into engagement with the casing 12. The shear screws 90 are designed to shear prior to screws 60 such that upper slip elements 54 and the double cone 58 will move longitudinally to set the lower slip elements 56 prior to setting the upper elements 54. The sleeve 61 prevents setting of the upper elements 54 until screw 60 is sheared.

7 In a second embodiment of the anchor 10 shown in Figures 4 and 5, operation is substantially identical to the first embodiment although the construction of the anchor 10 is slightly different. As shown in Fig. 5, a f ixed lower slip cone 156 is a separate component from a nose sub 124. Furthermore, the anti-rotation key 162 is associated with a lower slip cone 156 and seats within the shorter slot 164 in the mandrel 20. The interlock means 172 is also slightly different as shown in Fig. 4. As with the first embodiment, the interlock means 172 comprises a locking ring 174 with first and second ratchet surfaces. However, the shear screws 160 are provided with a spacer 190 having a ratchet surface 192 which cooperates with the ratchet surface 178 of the upper slip cone 154. Accordingly, the shear screws 160 extend through the interlock means.

operation of the hydraulically set anchor 10 within a cased well bore 12 is identical for both embodiments of the anchor 10. With the anchor 10 connected to a well tool such as a simple running tool or a whipstock through the sub 14, hydraulic fluid pressure is supplied through the passageway 18 of the sub 14 and the passageway 32 of the mandrel 20. The increased fluid pressure within the piston cylinder 38 will exert a downward f orce on the piston head 42. At a predetermined pressure, the screws 90 will shear releasing the slip cone 58 from the mandrel 20 and allowing the piston assembly 42 to move the slip cone 58 in the f irst downhole direction. once the lower elements 56 are set, the screw 60 will shear allowing the upper elements 54 to set and freeing the locking housing 59. As this occurs, the second ratchets So of the locking nut 74 will move across the ratchet surface 82 of the mandrel 20. As the upper slip elements 54 move towards the fixed lower slip elements 56, the slip elements will expand outwardly until the teeth of the slip elements are imbedded into the casing 12 anchoring the 8 i 1 1 1 i i -1 1 1 i i 1 1 1 device therein. As is shown in Fig. 2, the anchor 10 may be utilized in different diameter casings 12 with only the degree of downhole movement of the upper slip elements 54 changing. With the slip assembly 52 set into the casing 12 the hydraulic pressure may be eliminated. The interlock means 72 will prevent the upper slip elements 54 from moving in the second uphole direction thereby preventing release of the anchor 10. Thus, the present invention provides a hydraulically set anchor 10 which provides secure anchoring for secondary well tools.

As an example of an application of the anchor 10, Figures 6 and 7 show the anchor 10 incorporated into a whipstock assembly 100 for directional drilling. In the embodiment shown in the drawings, the anchor 10 is secured to the lower end of the whipstock 100 which in turn is connected to a running string 102. The running string 102 is used to position the whipstock 100 as well as supply the fluid pressure required to set the anchor 10. A fluid passageway 104 through the running string 102 and the whipstock 100 communicates with the axial passageway 18 of the anchor 10. Once the anchor 10 has been set to secure the whipstock 100 the running string 102 is disconnected form the whipstock 100 to allow a mill 106 or other cutting tool to be run into the hole for cutting through the casing 108. However, upon disconnection of the running sting 102 the hydraulic pressure from above will be cut off causing the prior known anchors to release. The interlock means 72 of the present invention prevents disengagement of the anchor 10. Thus, the anchor 10 and whipstock 100 will remain set in the casing 108 allowing the necessary milling operation.

In addition to running the whipstock 100 into the hole using a string 102, the whipstock 100 may be attached directly to the mill 106 resulting in a single trip 9 - - ' 1.4 ',, r operation. The anchor 10 could also be run and set independently for other operations although the hydraulically set anchor 10 lends itself f or use with a whipstock 100 since orientation of the whipstock within the casing 108 is crucial. The prior known mechanically set anchors required rotation of the string causing the offset surface of the whipstock to become disorientated from the desired placement. Moreover, it was previously believed that only packers could be used in such operations because of the pressure compensation properties of the packing elements. However, the present invention provides an anchor 10 which can be positively and securely set within a casing using hydraulic pressure. The shallow angles of the slip elements and slip cones allows secure engagement with the casing under reasonably attainable hydraulic pressures.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as some modifications will be obvious to those skilled in the art without departing from the scope of the appended claims.

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Claims

1. An anchor for well tools, said anchor being hydraulically set within a cased well bore using hydraulic fluid supplied to the anchor through a well tool, said anchor comprising: an inner mandrel having a fluid passageway selectively communicating with the hydraulic fluid supply; a piston cylinder in fluid communication with said fluid passageway of said mandrel, said cylinder having piston means slidably disposed therein; a slip assembly mounted to said mandrel, said slip assembly including at least one movable slip cone and a plurality of slip elements selectively expandable into anchoring engagement with the cased well bore upon movement of said at least one movable slip cone, said at least one movable slip cone movable in response to extension of said piston means within said cylinder; and interlock means for preventing retraction of said slip elements from the cased well bore.

2. The anchor as defined in claim I wherein said slip assembly includes a lower fixed slip cone, an upper movable slip cone and a plurality of slip elements, said slip elements expandable into anchoring engagement upon movement of said upper slip cone in a first direction towards said lower slip cone.

3. The anchor as defined in claim 2 wherein said interlock means comprises a locking nut engaging said mandrel and said movable upper slip cone, said locking nut positionally captured between said upper slip cone and said mandrel such that as said upper slip cone moves in said 11 f irst direction relative to said mandrel, said locking nut prevents said upper slip cone from moving in a second direction relative to said mandrel.

4. The anchor as def ined in claim 1 wherein said mandrel includes a partial axial bore and a lateral bore forming said fluid passageway.

5. The anchor as defined in claim 4 and further comprising an adapter sub f or selectively connecting the well tool to said anchor, said adapter sub including an axial fluid passageway communicating with said partial axial bore of said inner mandrel for supply of the hydraulic fluid.

6. The anchor as def ined in claim 5 wherein said cylinder is f ormed by an annulus surrounding said mandrel, said annulus fluidly communicating with said lateral bore of said fluid passageway.

7. The anchor as defined in claim 6 wherein said annulus is formed between an outer wall and said inner mandrel, said outer wall extending from said adapter sub.

8. The anchor as defined in claim 6 wherein said piston means is received within said annular cylinder, said piston means includes an annular piston head sealingly received within said cylinder and a piston rod extending from said piston head and engaging said upper slip cone whereby movement of said piston head within said annular cylinder moves said upper slip cone in said first direction to drive said slip elements into engagement with the cased well bore.

12 1 1 1 1 1 i 1 1 1 i 1 1 i i i i i i 1 1 i i 1 1 1 1 1 i i i if 9. The anchor as def ined in claim 3 wherein said upper and lower slip cones include an interface surface cooperating with corresponding surfaces on said slip elements, said interface surfaces having a slope of less than 20 degrees.

10. The anchor as def ined in claim 9 wherein said interface surfaces have a slope of less than 12 degrees.

11. An anchor for well tools, said anchor being hydraulically set within a cased well bore using hydraulic f luid supplied to said anchor through a well tool, said anchor comprising: an inner mandrel having a fluid passageway selectively communicating with the hydraulic fluid supply; a piston cylinder in fluid communication with said fluid.passagaway of said mandrel, said cylinder formed by an annulus surrounding said mandrel and enclosed by an outer wall, said cylinder having a piston assembly slidably disposed therein; a slip assembly mounted to said mandrel, said slip assembly including a movable upper slip cone, a f ixed lower slip cone, and a plurality of slip elements selectively expandable into anchoring engagement with the cased well bore upon movement of said movable slip cone in a f irst direction, said movable slip cone engaging said piston assembly whereby said movable slip cone moves in said first direction upon extension of said piston assembly within said cylinder; and interlock means disposed between said upper slip cone and said mandrel for preventing movement of said upper slip cone in a second direction thereby preventing retraction of said slip elements from the cased well bore.

13 12. The anchor as def ined in claim 11 wherein said interlock means comprises a locking nut engaging said mandrel and said movable upper slip cone, said locking nut having first ratchet teeth cooperating with ratchet teeth on said ipper slip cone and second ratchet teeth cooperating with ratchet teeth on said mandrel such that said locking nut allows movement of said upper slip cone in said f irst direction relative to said mandrel and prevents movement of said upper slip cone in said second direction relative to said mandrel.

13. The anchor as defined in claim 11 and further comprising an adapter sub for selectively connecting the well tool to said anchor, said adapter sub connected to said mandrel and said outer wall to f orm an end wall of said piston cylinder and including an axial f luid passageway of said Pandrel.

14. The anchor as def ined in claim 11 wherein said piston assembly includes an annular piston head sealingly received within said cylinder and a piston rod extending from said piston head and engaging said upper slip cone.

15. The anchor as def ined in claim 14 wherein said upper and lower slip cones include an interface surface cooperating with corresponding bottom surfaces on said slip elements, said interface surfaces having a slope of less than 12 degrees.

16. An anchor for well tools, said anchor being hydraulically set within a cased well bore using hydraulic f luid supplied to said anchor through a well tool, said anchor comprising:

14 i 7 x 1 1 1 1 i 1 i 1 i I i i i i 1 j 1 1 i 1 i 1 1 i an inner mandrel having a f luid passageway selectively communicating with the hydraulic fluid supply; an adapter sub connected to said mandrel and including an axial passageway communicating with said fluid passageway of said mandrel, said sub including means f or selectively connecting said anchor to the well tool; a piston cylinder in fluid communication with said fluid passageway of said mandrel, said cylinder formed by an annulus surrounding said mandrel and enclosed by an outer wall extending from said adapter sub, said cylinder having a piston assembly slidably disposed therein; a slip assembly mounted to said mandrel, said slip assembly including a movable upper slip cone, a fixed lower slip cone, and a plurality of slip elements selectively expandable into anchoring engagement with the cased well bore upon movement of said upper slip cone in a first direction, said piston assembly engaging said upper slip cone such that upon extension of said piston assembly within said cylinder said upper slip cone moves in said first direction to expand said slip elements into engagement with the cased well bore; and interlock means disposed between said upper slip cone and said mandrel for preventing movement of said upper slip cone in a second direction thereby preventing retraction of said slip elements from the cased well bore.

17. The anchor as def ined in claim 16 wherein said interlock means comprises a locking nut engaging said mandrel and said movable upper slip cone, said locking nut having first ratchet teeth cooperating with ratchet teeth on said upper slip cone and second ratchet teeth cooperating with ratcheL teeth on said mandrel.

18. The anchor as def ined in claim 16 wherein said upper and lower slip cones include an interface surface cooperating with corresponding bottom surf aces on said slip elements, said interface surfaces having a slope of less than 12 degrees.

19. A whipstock assembly for changing the direction of drilling through a cased well bore comprising:

a running tool for positioning said whipstock assembly in the cased well bore, said running tool having a fluid passageway; whipstock connected to said running tool; hydraulically set anchor connected to said whipstock, said anchor including a fluid passageway, a hydraulically set slip assembly and interlock means for preventing retraction of said slip assembly; and fluid passage means for supplying hydraulic fluid from said running tool to said fluid passageway of said anchor.

20. The whipstock assembly as defined in claim 19 wherein said anchor further comprises a piston cylinder in fluid communication with said fluid passageway of said anchor, said slip assembly movable into setting engagement with the cased well bore in response to extension of said piston slidably disposed in said cylinder.

21. A whipstock assembly for changing the direction of drilling through a cased well bore comprising:

mill for forming an opening in the well bore casing; whipstock detachably connected to said mill; and hydraulically set anchor connected to said whipstock, whereby said assembly can be run into and set within the cased well bore for milling an opening in the casing in one trip of the assembly.

16 1 i 1 i i 1 1 i 1 i i 1 2. An -ancncr for settin,,,. L,,II Iy - nerein before describec uith tc5 Figures 1 to --- or Figures 4 anc ED of' t.nt drawings.

23. A well tool whipstock assembly including an anchor as in any prectding clairi...

24. A well tool whipstock assembly su3stantially as nereinbefore described witn refer2nc.-- tD and as snown in the accompanying drawings.

17 Published 1992 atTbe Patent Office. Concept House. Cardiff Road, Newport, Gwent NP9 IRH. Further copies may be obtained from Sales Branch. Unit 6, Nine Mile Point. Cwmfelinfach. Cross Keys, Newport, NPl 7HZ. Printed by Multiplex techniques ltd. St Mary Cray, Kent.