CA2003348C - Casing hanger running and retrieval tools - Google Patents

Abstract

A tool for setting or retrieving a packoff between the casing hanger and the wellhead utilizes differential area pistons. The tool has a mandrel which connects to a string of drill pipe. The mandrel carries a body and is axially movable relative to the body. A sleeve is carried by the body for connection to the packoff. A sleeve piston is carried by the body for relative movement relative to the body. A mandrel piston is carried by the mandrel for movement with the mandrel. Passages in the body communicate the mandrel piston with the sleeve piston and contain an incompressible fluid. Axial movement of the mandrel causes the pressure to increase to drive the sleeve piston downward to set the packoff, or in another embodiment, upward to retrieve the packoff.

Description

3 1. Field of the Invention:

This invention relates in general to tools for 6 running and retrieving casing hangers in subsea wells, 7 and in particular to a tool that utilizes pressure 8 intensification through differential area pistons to 9 set and retrieve the packoff for a casing hanger.
11 2. Description of the Prior Art:

13 The subsea well of the type concerned herein will 14 have a wellhead supported on the subsea floor. One or more strings of casing will be lowered into the 16 wellhead from the surface, each supported on a casing 17 hanger. The casing hanger i8 a tubular member that is 18 secured to the threaded upper end of the string of 19 casing. The casing hanger lands on a landing shoulder in the wellhead, or on a previously installed casing 21 hanger having larger diameter casing. Cement is pumped 22 down the string of casing to flow back up the annulus 23 around the string of casing. After the cement hardens, 24 a packoff is positioned between the wellhead bore and an upper portion of the casing hanger. This seals the 26 casing hanger annulus.

28 One type of packoff proposed utilizes a metal seal ~9 so as to avoid deterioration with time that may occur with elastomeric seals. Metal seals require a much 31 higher force to set than elastomeric seals. Prior art 32 running tools have employed various means to apply the 33 downward force needed to set the packoff. Some prior - 20033~8 1 art tools use rotation of the drill string to apply 2 setting torque. It is difficult to achieve sufficient 3 torque to generate the necessary forces for a metal 4 packoff, because the running tool may be located more than a thousand fee~ below the water surface in deep 6 water.

8 Other running tools and techniques shown in the g patented art apply pressure to the annulus surrounding the drill string on which the running tool is 11 suspended. The amount of annulus pressure is limited, 12 however, to the pressure rating of the riser through 13 which the drill string extends, which is normally not 14 enough to set a metal packoff.
16 Higher pressures can be achieved by pumping 17 through the drill string. However, this requires a 18 running tool with some type of ports that are opened 19 and closed from the surface. This is necessary because cement must first be pumped down the drill string. The 21 ports may be opened and closed by dropping a ball or 22 dart. This requires a considerable amount of time, 23 however, for the ball to reach the seat. Rig time is 24 quite expensive. Another method employs raising and lowering the drill pipe and rotating in various manners 26 to engage and disengage J-slots to open and close 27 ports. This has a disadvantage of the pins for the J-28 slots wearing and not engaging properly.

Also, occasionally, a packoff may need to be 31 retrieved to the surface. A floating vessel located at 32 the surface will connect to the wellhead by means of a 33 riser. A retrieving tool is lowered on a drill string.

2~03348 1 The retrieving tool has a means for securing to the 2 packoff. Then the drill string is pulled upward to 3 release the packoff.

While this is satisfactory for elastomeric seal 6 packoffs, it is more difficult to achieve with a metal 7 packoff. Elastomeric packoffs are set at much lower 8 forces than metal packoffs. It may be difficult to 9 achieve sufficient pulling force with the drill string to pull a metal packoff loose.

1 SUMMARY pF THE INVENTION

3 In this invention, the drill string axial movement 4 is used to set and retrieve the packoff. In one embodiment, the weight of the drill string is used. In 6 another embodiment, the drill string is pulled upward.
7 The drill string weight, itself, does not have 8 sufficient force to set the packoff. The force due to g the drill string weight is intensified by using differential pistons. The running tool has a mandrel 11 that is connected to the drill string. The mandrel has 12 a mandrel piston that moves with the mandrel. The 13 mandrel carries a body that engages the casing hanger.
14 The body has a setting sleeve piston that has a much larger pressure area than the mandrel piston. Sealed 16 hydraulic passages connect the chamber of the mandrel 17 piston with the chamber of the setting sleeve piston.

19 When setting the packoff, as the drill string is lowered relative to the body, the mandrel piston will 21 apply hydraulic pressure to the liquid contained in the 22 passages. This pressure acts on the setting sleeve 23 piston, which in turn applies a downward force on the 24 setting sleeve. The downward force of the setting sleeve will be much higher than the direct force from 26 the weight of the drill string because of the 27 intensification due to the differential area pistons.

29 Preferably the body has two parts, an upper body and a lower body. The upper body is carried in an 31 upper position while r~ln~nq the casing hanger and 32 while cementing. Then, the mandrel and the upper body 33 are lowered relative to the lower body to position the 1 packoff.assembly in the annular space ~e~ween the 2 casing hanger and wellhead. Then, the mandrel is 3 lowered relative to both the upper body and lower body 4 to apply hydraulic pressure to the setting sleeve piston.

7 In another embodiment, the drill pipe and mandrel 8 are pulled upward to move the sleeve downward to set 9 the packoff. In still another embodiment, the tool is used to retrieve the packoff.

Z0033~8 3 Figures la and lb are quarter sectional views of 4 a running tool constructed in accordance with this invention, and shown in the running in and cementing 6 position.

8 Figures 2a and 2b are quarter sectional views of 9 the running tool of Figure 1, showing the packoff being moved into position for setting after the casing hanger 11 has been cemented.

13 Figures 3a and 3b are quarter sectional views of 14 the running tool of Figure 1, showing the packoff when fully set, with the mandrel in the lowermost position.

17 Figures 4a and 4b are quarter sectional views of 18 the running tool of Figure 1, showing the mandrel moved 19 back to an upper position relative to the upper body to release the running tool from the casing hanger.

22 Figures 5a and 5b are quarter sectional views of 23 the running tool of Figure 1, showing the running tool 24 released from the casing hanger after the packoff has been set.

27 Figure 6 is a partial vertical sectional view of a 28 first alternate embodiment of a running tool 29 constructed in accordance with this invention and shown in the running in position.

- 2~0334~3 1Figure 7 is a partial vertical sectional view of 2 the running tool of Figure 6, and shown in a position 3 of lowering the upper body relative to the lower body.

Figure 8 is a partial vertical sectional view of 6 the running tool of Figure 6, and shown in a retrieving 7 position.

g Figure 9 is a partial vertical sectional view of a portion of the running tool of Figure 6, in the 11 position shown in Figure 8.

13 Figures lOa and lOb are quarter sectional views 14 of a second alternate embodiment of a running tool constructed in accordance with this invention, and 16 shown in the running in and cementing position.

18 Figures lla and llb are quarter sectional views of 19 the running tool of Figures lOa and lOb, showing the packoff being moved into position for setting after the 21 casing hanger has been cemented.

23 Figures 12a and 12b are quarter sectional views of 24 the running tool of Figures lOa and lOb, showing the packoff when fully set, with the mandrel moved back to 26 an upper position.

28 Figures 13a and 13b are quarter sectional views of 29 the running tool of Figures lOa and lOb, showing the running tool released from the casing hanger.

33 Figure 14 is a quarter cross-sectional view of a 34 fourth embodiment illustrating a tool constructed in - 200;~348 1 accordance with this invention, used for retrieving a 2 packoff and shown with the mandrel in a lower 3 position.

Figure 15 is a quarter cross-sectional view of the 6 tool of Figure 14, and showing the mandrel lifted into 7 an upper position for retrieving the packoff.

2 Referring to Figures la and lb, and more 3 particularly to Figure lb, wellhead 11 is a tubular 4 member extending upward from the subsea floor. An internal landing shoulder 13 is located in the bore 14 6 of the wellhead 11. T~n~i ng shoulder 13 is frusto-7 conical. A set of wickers 15 is located a short 8 distance above the landing shoulder 13. Wickers 15 are g small, parallel, circumferential grooves.
11 A casing hanger 17 lands on the landing shoulder 12 13. Casing hanger 17 is a tubular member that is 13 secured to the upper end of a string of casing (not 14 shown). An annular clearance 19 exists between an upper portion of the casing hanger 17 and the bore 14 16 of the wellhead 11. A set of wickers 21 is formed on 17 the casing hanger 17. Wickers 21 are of the same 18 configuration, but extend upward farther and do not 19 extend as far down as the wellhead wickers 15. Two large circumferential grooves 23 are located on the 21 inner diameter of the upper portion of the casing 22 hanger 17.

24 Casing hanger 17 is lowered into place and set by a running tool 25. R~nn~ng tool 25 includes a mandrel 26 27 that has an upper end cont~n~ng threads 26 (Fig.
27 3a) for connection to the lower end of the string of 28 drill pipe (not shown). The drill pipe will be lowered 29 through a riser (not shown) that extends from a floating vessel down to the wellhead 11. A collar 29 31 is secured to the lower end of the mandrel 27. Collar 32 29 has exterior threads 3la, 3lb. The threads 3lb are 33 of larger diameter than the threads 3la. The threads 20033~8 1 31a, 31b are adapted to screw into mating threads 2 formed in a lower body 33.

4 An engaging element, preferably a split ring 35, is carried by the lower body 33. The ring 35 will 6 extend from the exterior of the lower body 33. The 7 ring 35 has a pair of annular bands separated by a 8 groove on the outer side. The bands are adapted to g mate with the grooves 23 in the casing hanger 17 to secure the lower body 33 to the casing hanger 17. Ring 11 35 will move between an extended position shown in 12 Figure lb to a retracted position shown in Figure 5b.
13 ~
14 A plurality of linking pins 37 extend through the lower body 33 radially inward from the ring 35. The 16 linking pins 37 are moved inward and outward by a cam 17 39, which is a solid ring. Cam 39 is carried inside a 18 cavity 40 in the lower body 33. Cam 39 has a pair of 19 lobes 41a, 4lb, which are annular bands separated by a central recess 43. The cam 39 will move axially 21 relative to the lower body 33.

23 Figure lb shows the cam 39 in an upper position 24 with the lower lobe 41b pressing the linking pins 37 and the ring 35 outward. Figure 2b shows the cam 39 in 26 a lower position, with the upper lobe 41a pressing the 27 linking pins 37 and the ring 35 outward. Figure 5b 28 shows the cam 39 in an intermediate position, with the 29 recess 43 engaging the linking pins 37, which allows the ring 35 to retract. The cam 39, linking pins 37 31 and ring 35 serve a~ connection means for releasably 32 connecting the rllnning tool 25 to the casing hanger 17.

1 The cam 39 is moved downward by retention means 2 comprising a split ring 45 secured in a recess 47 in 3 the mandrel 27. Split ring 45 bears against the upper 4 end of the cam 39 to cause the cam 39 to move downward with the mandrel 27. The flexibility of the split ring 6 45 allows it to retract into the recess 47 and slide 7 past the cam 39 when the cam is located in the lower 8 position bearing against the bottom of the cavity 40.
g In Figure 2b, the split ring 45 is located a considerable distance below the cam 39.

12 The cam 39 moves back to the intermediate position 13 by means of the collar 29, as shown in Figure lb. The 14 collar 29 has an upper edge that engages the lower end of the cam 39. When the collar 29 is fully screwed 16 into the lower body 33, the upper end of the collar 17 supports the cam 39 in the upper position. In the 18 position of Figure 5b, the threads 31a and 31b have 19 contacted the mating threads in the lower body 33, but have not yet been screwed into place. In this 21 position, the upper end of the collar 29 ~upports the 22 cam 39 in the intermediate position.

24 The lower body 33 is preferably constructed in two parts, the upper portion 49 being secured by threads to 26 the lower portion. Ring 35 locates in an annular space 27 between the lower body 33 and its upper portion 49.
28 The upper portion 49 of the lower body 33 extends 29 upward concentric with the mandrel 27. Inner and outer seals 51, 53 are located on the inner and outer 31 diameters of this lower body upper portion 49.

2~033~8 1 Referring to Figure la, the running tool 25 has an 2 upper body 55. Upper body 55 has an upper position 3 relative to the lower body 33 that is shown in Figures 4 la and lb and also in Figures 5a and 5b. In the other figures, the upper body 55 is located in a lower 6 position relative to a lower body 33. The upper body 7 55 is maintained in the upper position during running 8 in and cementing by a locking element comprising a 9 split ring 57 which is shown in Figure lb.
11 When the upper body 55 is in the upper position, 12 split ring 57 locates in a recess 59 formed on the 13 outer diameter of the mandrel 27. In both the upper 14 and lower positions of the upper body 55, split ring 57 remains located in a cavity 61 contained in the lower 16 portion of the upper body 55. Cavity 61 has a radial 17 width that is at least as wide as the radial thickness 18 of the split ring 57 so as to allow the split ring 57 19 to expand outward into the cavity 61. This allows the split ring 57 to move out of the mandrel recess 59 as 21 shown in Figure 2b, to enable the mandrel 27 to be 22 lowered relative to the upper body 55.

24 A plurality of pins 63 extend radially outward from split ring 57. Pins 63 engage a latch ring 65 26 that is also split. Latch ring 65 has outer threads 67 27 and inner grooves 69. The inner grooves 69 engage 28 mating grooves in the upper body 55 to retain the latch 29 ring 65 with the upper body 55. The latch ring threads 67 are configured to ratchet past and engage mating 31 threads 71 formed in the upper portion of the c~sing 32 hanger cavity 40. The threads 67, 71, are of a saw-33 tooth configuration.

2In Figure lb, the latch ring 65 is positioned 3above the casing hanger threads 71. In Figures 2b and 43b, the latch ring 65 is engaging the threads 71. When 5engaging the threads 71, the latch ring 65 expands 6outward. The pins 63 move outward, allowing the split 7ring 57 to move outward. This withdraws the split ring 857 from the recess 59. While engaging the threads 71, gthe grooves 69 move outward to some extent from the 10mating grooves in the upper body 55, but still remain 11in engagement. The latch ring 65 and associated 12elements serve as means for latching the upper body 55 13to the lower body 33 when the upper-body 55 is in the 14lower position, to prevent any axial movement of the 15upper body 55 relative to the lower body 33.

17Referring to Figure la, the upper body has an 18outer portion 73 that is substantially the diameter of 19the wellhead bore 14. The outer portion 73 depends 20from the upper body 55. A setting sleeve 75 is carried 21on the upper body outer portion 73. Setting sleeve 75 22is secured by a ring 76 that is fixed to the outer 23portion 73 80 that the sleeve 75 can move axially a 24limited extent relative to the upper body 55. A key 25(not shown) causes the setting sleeve 75 to rotate in 26unison with the upper body 55.

28Referring to Figure lb, the setting sleeve 75 i8 a 29tubular member that extends downward from the upper 30body 55. A threaded ring 77 is located on the lower 31end of the setting ~leeve 75. Threaded ring 77 is a 328pl it, ratchet type ring that engages threads in a 33wedge ring 79. The wedge ring 79 is secured to a metal 1 seal packoff 81 by means of a collar 82. The packoff 2 81 has a central annular cavity 83 that receives the 3 wedge ring 79.

The setting sleeve 75 will move the packoff 81 6 from an upper position shown in Figure lb to a lower 7 position shown in the other figures. In the lower 8 position, the packoff 81 is located in the annular g clearance 19 between the casing hanger 17 and the lo wellhead 11. Furthermore, the setting sleeve 75 will 11 move the wedge ring 79 downward from the upper position 12 shown in Figure lb to a setting position shown in 13 Figure 3b. In that position, the wedge ring 79 expands 14 portions of the packoff 81 on both sides of the cavity 83 to form a metal seal.

17 While running the casing hanger 17 in and while 18 cementing, fluid in the riser and wellhead bore 14 is 19 free to flow up through a return flow passage 85 in the setting sleeve 79 and a return flow passage 86 in the 21 upper body 55 (Fig. la). There are also return flow 22 passages through the casing hanger 17, but these are 23 not shown in the drawings.

The lower body upper portion 49 sealingly locates 26 between the upper body 55 and the setting sleeve 75.
27 This is not a closed chamber, however, as fluid is free 28 to flow out through the passage 87 shown in Figure la.

After the upper body 55 has been moved to its 31 lower position shown in Figure 2b, the setting sleeve 32 75 is then moved downward relative to the upper body 55 33 to set the packoff 81. This is handled by a setting 2003;~48 1 sleeve piston 89 shown in Figure la. The setting 2 sleeve piston 89 is carried in a chamber 90 located 3 between the upper body inner portion 91 and upper body 4 outer portion 73. The setting sleeve piston 89 has seals 92 that will sealingly slide within chamber 90.
6 The chamber 90 of the setting sleeve piston 89 is 7 supplied with a substantially incompressible liquid, 8 such as hydraulic fluid, through hydraulic passages 93.
g The hydraulic passages 93 communicate with a chamber 95 formed between the bore of the upper body 55 and the 11 exterior of the mandrel 27, as shown in Figure lb.

13 A mandrel piston 97 is sealingly carried in the 14 chamber 95. The mandrel piston 97 is integrally formed on the mandrel 27 and protrudes outward. Chamber 95 16 is sealed by seals 98 on the mandrel piston 97. The 17 hydraulic passage 93 communicates the chamber 95 of the 18 mandrel piston 97 with the chamber 90 of the setting 19 sleeve piston 89. The hydraulic fluid contAine~ in the chambers 90, 95 and passage 93 is sealed from any 21 exterior fluids in the riser (not shown), wellhead bore 22 14 or within the drill pipe (not shown). Downward 23 movement of the mandrel piston 97 increases the 24 pressure of the hydraulic fluid in the passage 93 to move the setting sleeve piston 89 downward.

27 The transverse cross-sectional area of the mandrel 28 piston 97, or pressure area, is much less than the 29 cross-sectional area or pressure area of the setting sleeve piston 89. Consequently, the downward force on 31 the mandrel 27 due to the drill string weight is 32 greatly intensified. That is, the downward force 33 exerted by the piston 89 on the setting sleeve 75 will - 20~3348 1be much higher than the downward force on the mandrel 227, which is limited to the weight of the drill string.
3Preferably, a sufficient difference exists between 4the pressure areas to increase a drill string weight on 5mandrel piston 97 of 20,000 pounds to provide a setting 6force on the setting sleeve piston 89 of about 500,000 7pounds.

9 Referring to Figure 2a, a series of teeth or castellations 99 are formed on the upper side of the 11 mandrel piston 97. The castellations 99 have slots 12 (not shown) between them that are adapted to engage a 13 pin 101. Pin 101 is located at the upper end of the 14 upper body 55. Pin 101 is secured in threads in the upper body 55. A collar 103 is located on the upper 16 end of the upper body 55. A wiper seal 105 is 17 positioned between the collar 103 and the outer 18 diameter of the mandrel 27.

In operation, the casing (not shown) will be 21 lowered into the well. The upper end of the casing 22 will be secured to the lower end of the casing hanger 23 17. As shown in Figure lb, the running tool 25 will be 24 connected to the casing hanger 17 through the ring 35.
The upper end of the mandrel 27 of the running tool 25 26 is connected to the lower end of a string of drill pipe 27 (not shown). The entire assembly is then lowered into 28 the well until the casing hanger 17 lands on the 29 landing shoulder 13 in the wellhead 11, as shown in Figure lb.

32 Then, cement is pumped down the drill pipe. The 33 cement will flow through the bore of the mandrel 27 to 1 the bottom of the casing string, then back up the 2 annulus surrounding the casing string. The returns 3 from the cement will flow through the passages (not 4 shown) in the casing hanger 17, and up through the passages 85 (Fig. lb) and passages 86 (Fig. la) to the 6 surface through the riser (not shown).

8 After the cement has set sufficiently, the drill g string is rotated to the right. This disengages the threads 31a, 31b from the lower body 33, as can be seen 11 by comparing Figure lb with Figure 2b. Once unscrewed, 12 the drill string is lowered, allowing the mandrel 27 to 13 move downward.

As mandrel 27 moves downward, the lower body 33 16 will remain stationary because it is seated in the 17 casing hanger 17. The upper body 55 will move downward 18 with the mandrel 27. This occur~ because the split 19 ring 57 (Fig. lb) retains the upper body 55 with the mandrel 27 for a certain distance. The cam 39 will 21 also move downward with the mandrel 27 for a short 22 distance until it reaches the bottom of cavity 40. The 23 split ring 45 will bear against the top of the cam 39, 24 causing this downward movement. When the cam 39 is in the lower position shown in Figure 2b, the ring 35 will 26 be maintained in the engaged position by means of the 27 upper lobe 4la. Once the cam 39 reaches the lower 28 position, the split ring 45 will contract into the 29 recess 47 and slide on past the cam 39.
31 The downward movement of the mandrel 27 con~inues 32 until the latch ring 65 (Fig. lb) engages the threads 33 71 in the lower body 33. When this occurs, the latch 1 ring 65 snaps outward. This allows the split ring 57 2 to expand outward from the recess 59 in the mandrel 27.
3 The mandrel 27 is then free to move further downward 4 relative to the upper body 55, as illustrated in Figure 2b.

7 When the upper body 55 is in the lower position, 8 the packoff 81 will be properly positioned in the 9 annular clearance 19 between the casing hanger 17 and the wellhead 11. The upper body 55 will be latched to 11 the lower body 33 so that it can not move upward 12 because of the latch ring 65. This is the position 13 shown in Figure 2b.

Continued downward movement of the mandrel 27 16 relative to the upper body 55 and lower body 33 causes 17 a pressure increase in the chambers 90, 95 and 18 hydraulic passage 93. The pressure increase acts on 19 the setting sleeve piston 89. The setting sleeve piston 89 acts on the setting sleeve 75. The setting 21 sleeve 75 applies downward force to the wedge ring 79.
22 The wedge ring 79 moves downward into the cavity 83, 23 which sets the packoff 81. The inner portion of the 24 packoff 81 embeds into the casing hanger wickers 21.
The outer portion of the packoff 81 embeds into the 26 wellhead bore wickers 15. The setting position is 27 illustrated in Figure 3b. When fully set, the upper 28 end of the setting sleeve 75 will be substantially 29 flush with the upper end of the lower body upper portion 49.

32 After testing, the running tool 25 may be 33 retrieved from the casing hanger 17. First, the drill 1 string is picked up to pull the mandrel 27 upward. At 2 a certain distance, the castellations 99 (Fig. 2a) will 3 engage the pin 101 as shown in Figure 4a. Then, the 4 drill string i8 rotated to the right again. The mandrel 27 will rotate. The castellations 99 and pin 6 101 will cause the upper body 55 to rotate with the 7 mandrel 27. This will cause the threaded ring 77 to 8 unscrew from the wedge ring 79. This rotation will 9 also cause the latch ring 65 to unscrew from thethreads 71. The mandrel 27 may then be picked up.
11 This is the position shown in Figures 5a and 5b.

13 As the mandrel 27 is picked up, the recess 59 will 14 move up and engage the split ring 57. This will cause the upper body 55 to begin moving upward with the 16 mandrel 27. The collar 29 will contact the lower side 17 of the cam 39 and move it up to intermediate position 18 shown in Figure 5b. The threads 31a and 31b will 19 contact the mating threads in the lower body 33 to limit the upward movement of the collar 29 to the 21 position shown in Figure 5b. The intermediate position 22 of the cam 39 allows the ring 35 to retract. The 23 entire running tool 25 may then be pulled to the 24 surface.
26 In the embodiments of Figures 6-9, the elements 27 which are similar to the first embodiment are either 28 not discussed, or when discussed, are indicated with a 29 prime symbol. The principal difference is in the manner of releasing the lower body 33' from the casing 31 hanger 17'. The mandrel 27' is secured by threads to 32 an annular insert 107, which may be considered a part 33 of the lower body 33'. The insert 107 has left-hand 1 threads 108 which secure the insert 107 to the lower 2 body 33'. While downhole, the insert 107 does not 3 unscrew from the lower body 33', rather it is removed 4 and installed only during disassembly and assembly at the surface.

7 An annular stop 109 is formed on the upper end of 8 the insert 107, extending into the cavity 40' of the g lower body 33'. The stop 109 serves as stop means for preventing a cam 111 from moving downward from its 11 lower position shown in Figures 6, 7. Cam 111 is 12 axially movable from the lower position shown in 13 Figures 6, 7 to the upper position shown in Figure 8.
14 Cam 111 has a central lobe 113 that pushes outward on link pins 37' and split ring 35' when cam 111 is in the 16 lower position. The lobe 113 maintains the split ring 17 35' in an engaged position with the casing hanger 17'.
18 When in the upper position of Figure 8, the lobe 113 19 passes above the link pins 37', allowing the split ring 35' to retract.

22 Cam 111 has an inner diameter that slidingly 23 receives the mandrel 27'. An annular slot 115, shown 24 more clearly in Figure 9, is located in the inner diameter of cam 111. Slot 115 inclines downward and 26 outward relative to the axis of mandrel 27'.

28 A spring element such as a split ring 117 locates 29 in the slot 115. Split ring 117 has a circular transverse cross-section and is considerably smaller in 31 cross-sectional diameter than the height of the slot 32 115. Split ring 117 is biased inward into engagement 33 with the mandrel 27'.

2 A recess 119 is formed on the exterior of the 3 mandrel 27', at a point so that it is initially above 4 the cam 111. As shown in Figure 9, the upper edge ll9a and the lower edge ll9b of the recess are bevelled.
6 The upper edge ll9a faces downward and outward, and the 7 lower edge ll9b faces downward and inward.

g In operation of the second embodiment, after the cement has set, the drill string and mandrel 27' are 11 rotated to the right to unscrew the mandrel 27' from 12 the lower body 33'. The insert 107 will not unscrew 13 because of the left-hand threads. As the mandrel moves 14 downward, the cam 111 remains stationary. The recess 119 will slide past the split ring 117, as indicated in 16 Figure 7. The upper edge ll9a pushes the split ring 17 117 outward into the slot 115 as it moves past.

19 The packoff 81' is set in the same manner as described in the first embodiment. To release the 21 running tool 25', the drill string and the mandrel 27' 22 are picked up. The recess 119 will move up and engage 23 the ring 117. The lower edge ll9b will push the ring 24 117 against the inclined upper edge of slot 115. The inclination of the lower edge ll9b and the upper edge 26 of slot 115 are substantially the same. This traps the 27 ring 117 between the lower edge ll9b and the upper 28 edge of slot 115. This locks the cam 111 to the 29 mandrel 27 for upward movement.
31 As the cam 111 moves upward, the lobe 113 passes 32 above the link pin 37'. This allows the ring 35' to 33 retract, releasing the lower body 33' from the casing 1 hanger ~7'. The setting sleeve 75' releases from the 2 packoff wedge ring 79' by a straight upward pull. The 3 grooves or threads on the ring 77' are configured to 4 allow releasing with a moderate upward pull. No rotation is necessary.

7 The upper body 55' will remain in the lower 8 position relative to lower body 33' as the running tool 9 25' is retrieved to the surface. The latch ring 65' is not unscrewed from the threads 71' until the running 11 tool 25' is at the surface. Consequently, there will 12 be no structure such as the castellations 99 or pin 101 13 (Fig 2a) for locking the mandrel 27'-to the upper body 14 55' for rotation.

17 A third embodiment is shown in Figures lOa through 18 13b. Referring to Figures lOa and lOb, and more 19 particularly to Figure lOb, wellhead 211 is a tubular member extending upward from the subsea floor. An 21 internal l~n~ng shoulder 213 is located in the bore 22 214 of the wellhead 211. T~n~ing shoulder 213 is 23 frusto-conical. A set of wickers 215 is located a 24 short distance above the landing shoulder 213. Wickers 215 are small, parallel, circumferential grooves.

27 A casing hanger 217 lands on the landing shoulder 28 213. Casing hanger 217 is a tubular member that is 29 secured to the upper end of a string of casing (not shown). An annular clearance 219 exists between an 31 upper portion of the casing hanger 217 and the bore 214 32 of the wellhead 211. Return flow passages 218 extend 33 through the casing hanger 217 to return fluid from the 34 annulus surrounding the casing with the annular 2~03348 1 clearanc,e 219 during cementing before the casing hanger 2 is fully set.

4 A set of wickers 221 is formed on the casing hanger 217. Wickers 221 are of the same configuration, 6 but extend upward farther and do not extend as far down 7 as the wellhead wickers 215. Two large circumferential 8 grooves 223 are located on the inner diameter of the 9 upper portion of the casing hanger 217.
11 Casing hanger 217 is lowered into place and set by 12 a running tool 225. Running tool 225 includes a 13 mandrel 227 that has an upper end containing threads 14 226 (Fig. 12a) for connection to the lower end of the string of drill pipe (not shown). The drill pipe will 16 be lowered through a riser (not shown) that extends 17 from a floating vessel down to the wellhead 211. A
18 shoulder 229 is secured to the lower end of the mandrel 19 227. Mandrel 227 has exterior threads 231a, 231b. The threads 23lb are of larger diameter than the threads 21 23la. The threads 23la, 23lb are adapted to screw into 22 mating threads formed in a lower body 233.

24 An engaging element, preferably a split ring 235, is carried by the lower body 233. The ring 235 will 26 extend from the exterior of the lower body 233. The 27 ring 235 has a pair of annular bands separated by a 28 groove on the outer side. The bands are adapted to 29 mate with the grooves 223 in the casing hanger 217 to secure the lower body 233 to the casing hanger 217.
31 Ring 235 will move between an extended position shown 32 in Figure lOb to a retracted position shown in Figure 33 14b.

20()3348 2 A plurality of linking pins 237 extend through the 3 lower body 233 radially inward from the ring 235. The 4 linking pins 237 are moved inward and outward by a cam 239, which is a solid ring. Cam 239 is carried inside 6 a cavity 240 in the lower body 233. Cam 239 has a pair 7 of lobes 24la, 24lb, which are annular bands separated 8 by a central recess 243. The cam 239 will move axially 9 relative to the lower body 233.
11 Figure lOb shows the cam 239 in an upper position 12 with the lower lobe 241b pressing the linking pins 237 13 and the ring 235 outward. Figure llb shows the cam 239 14 in a lower position, with the upper lobe 241a pressing the linking pins 237 and the ring 235 outward. Figure 16 13b shows the cam 239 in an intermediate position, with 17 the recess 243 engaging the linking pins 237, which 18 allows the ring 235 to retract. The cam 239, linking 19 pins 23~ and ring 235 serve as connection means for releasably connecting the running tool 225 to the 21 casing hanger 217.

23 The cam 239 i5 held in the upper and the 24 intermediate positions by means of a shoulder 229 which engages the lower end of the cam 239. When the mandrel 26 227 is fully screwed into the lower body 233, the upper 27 end of the shoulder 229 supports the cam 239 in the 28 upper position. Pins 245 are secured to the cam 239 29 and extend through holes in the bottom of cavity 240.
The pins 245 provide an upper limit for the movement of 31 the cam 239.

1In the position of Figure 13b, the threads 23la 2and 23lb have contacted the mating threads in the lower 3body 233, but have not yet been screwed into place. In 4this position, the shoulder 229 supports the cam 239 in 5the intermediate position.

7 The lower body 233 is preferably constructed in 8 two parts, the upper portion 249 being secured by g threads to the lower portion. Ring 235 locates in an annular space between the lower body 233 and its upper 11 portion 249. The upper portion 249 of the lower body 12 extends upward concentric with the mandrel 227. Inner 13 and outer seals 251, 253 are located on the inner and 14 outer diameters of this lower body upper portion 249.
16 Referring to Figure lOa, the running tool 225 has 17 an upper body 255. Upper body 255 has an upper 18 position relative to the lower body 233 that is shown 19 in Figures lOa and lOb and also in Figures 13a and 13b.
In the other figures, the upper body 255 is located in 21 a lower position relative to a lower body 233. The 22 upper body 255 moves to the lower position by its own 23 weight and by the contact of a downward facing shoulder 24 257 on the exterior of mandrel 227, which is shown in Figure lla.

27 A split latch ring 265 is carried on the exterior 28 of the lower end of the upper body 255. Latch ring 265 29 has outer threads 267. The latch ring threads 267 are configured to ratchet past and engage mating threads 31 271 formed in the upper portion of the casing hanger 32 cavity 240. The threads 267, 271 are of a saw-tooth 33 configuration.

2(~03348 2 In Figures lOa and lOb, the latch ring 265 is 3 positioned above the casing hanger threads 271. In 4 Figures llb and 12b, the latch ring 265 is engaging the threads 271. The latch ring 265 and threads 271 serve 6 as means for latching the upper body 255 to the lower 7 body 233 when the upper body 255 is in the lower 8 position, to prevent any axial movement of the upper g body 255 relative to the lower body 233.
11 Referring to Figure lOa, the upper body 255 has an 12 outer portion 273 that is substantially the diameter of 13 the wellhead bore 214. The outer portion 273 depends 14 from the upper body 255. A setting sleeve 275 is carried on the upper body outer portion 273. Setting 16 sleeve 275 is secured by a ring 276 that is fixed to 17 the outer portion 273 so that the sleeve 275 can move 18 axially a limited extent relative to the upper body 19 255. A key (not shown) causes the setting sleeve 275 to rotate in unison with the upper body 255.

22 Referring to Figure lOb, the setting sleeve 275 is 23 a tubular member that extends downward from the upper 24 body 255. A threaded ring 277 is located on the lower end of the setting sleeve 275. Threaded ring 277 is a 26 split, ratchet type ring that engages threads in a 27 wedge ring 279. The wedge ring 279 i8 secured to a 28 metal seal packoff 281 by means of a collar 282. The 29 packoff 281 has a central annular cavity 283 that receives the wedge ring 279.

32 The setting sleeve 275 will move the packoff 281 33 from an upper position shown in Figure lOb to a lower 1 position shown in the other figures. In the lower 2 position, the packoff 281 is located in the annular 3 clearance 219 between the casing hanger 217 and the 4 wellhead 211. Furthermore, the setting sleeve 275 will move the wedge ring 279 downward from the upper 6 position shown in Figure lOb to a setting position 7 shown in Figure 12b. In that position, the wedge ring 8 279 expands portions of the packoff 281 on both sides 9 of the cavity 283 to form a metal seal.
11 While running the casing hanger 217 in and while 12 cementing, fluid in the riser and wellhead bore 214 is 13 free to flow up through a return flow passage 285 in 14 the setting sleeve 279 and a return flow passage 286 in the upper body 255 (Fig. lOa).

17 The lower body upper portion 249 sealingly locates 18 between the upper body 255 and the setting sleeve 275.
19 This is not a closed chamber, however, as fluid is free to flow out through the passages (not shown) in the 21 setting sleeve 275.

23 After the upper body 255 has been moved to its 24 lower position shown in Figure llb, the setting sleeve 275 is then moved downward relative to the upper body 26 255 to set the packoff 281. This is handled by a 27 setting sleeve piston 289 shown in Figure lOa. The 28 setting sleeve piston 289 is carried in a chamber 290 29 located between the upper body inner portion 291 and upper body outer portion 273. The setting sleeve 31 piston 289 has seals 292 that will sealingly slide 32 within chamber 290. During the setting process, the 33 chamber 290 of the setting sleeve piston 289 will 1 receive a substantially incompressible liquid, such as 2 hydraullc fluid, through hydraulic passages 293. The 3 hydraulic passages 293 communicate with a chamber 295 4 formed between the bore of the upper body 255 and the exterior of the mandrel 227, as shown in Figure lla.

7 A mandrel piston 297 is sealingly carried in the 8 chamber 295. The mandrel piston 297 is secured to the 9 mandrel 227 for movement therewith and protrudes outward. The chamber 295 extends upward from the 11 mandrel piston 297 when the mandrel piston 297 is in 12 the lower position shown in Figure llb. Chamber 295 is 13 sealed by seals 298 on the mandrel piston 297. The 14 hydraulic passage 293 communicates the chamber 295 of the mandrel piston 297 with the chamber 290 of the 16 setting sleeve piston 289. The hydraulic fluid 17 contained in the chambers 290, 295 and passage 293 is 18 sealed from any exterior fluids in the riser (not 19 shown), wellhead bore 214 or within the drill pipe (not shown). Upward movement of the mandrel piston 297 21 increases the pressure of the hydraulic fluid in the 22 passage 293 to move the setting sleeve piston 289 23 downward.

The transverse cross-sectional area or pressure 26 area of the mandrel piston 297 is much less than the 27 cross-sectional area or pressure area of the setting 28 sleeve piston 289. Consequently, the upward force on 29 the mandrel 227 due to the drill string tension is greatly intensified. That is, the downward force 31 exerted by the setting sleeve piston 289 on the setting 32 sleeve 275 will be much higher than the upward force on 33 the mandrel 227. Preferably, the pressure area of the 1 mandrel piston 297 is about one-tenth that of the 2 pressure area of the setting sleeve piston 289, so that 3 60,000 pounds pull on the drill string will provide a 4 setting force of 600,000 pounds.

6 Referring to Figure llb, a lug 299 is formed on 7 the upper side of the mandrel piston 297. The lug 299 8 is adapted to engage a slot 301 (Fig. lOa). Slot 301 9 is located at the upper interior of the upper body 255.
When engaged, as shown in Figures lOa and 13a, the 11 upper body 255 will rotate with the mandrel 227.

13 In operation, the casing (not shown) will be 14 lowered into the well. The upper end of the casing will be secured to the lower end of the casing hanger 16 217. As shown in Figure lOb, the running tool 225 will 17 be connected to the casing hanger 217 through the ring 18 235. The upper end of the mandrel 227 of the running 19 tool 225 i8 connected to the lower end of a string of drill pipe (not shown). Hydraulic fluid will be 21 located in the passages 93. The entire assembly is 22 then lowered into the well until the casing hanger 217 23 lands on the landing shoulder 213 in the wellhead 211, 24 as shown in Figure lOb.
26 Then, cement is pumped down the drill pipe. The 27 cement will flow through the bore of the mandrel 227 to 28 the bottom of the casing string, then back up the 29 annulus surrounding the casing string. The returns from the cement will flow through the passages 218 in 31 the casing hanger 217, and up through the passages 285 32 (Fig. lOb) and passages 286 (Fig. lOa) to the surface 33 through the riser (not shown).

2 After the cement has set sufficiently, the drill 3 string is rotated to the right. This disengages the 4 threads 231a, 231b from the lower body 233, as can be seen by comparing Figure 10b with Figure llb. Once 6 unscrewed, the drill string is lowered, allowing the 7 mandrel 227 to move downward.

9 As mandrel 227 moves downward, the lower body 233 will remain stationary because it is seated in the 11 casing hanger 217. The mandrel piston 297 moves 12 downward in mandrel chamber 295, drawing hydraulic 13 fluid from the setting sleeve chamber 290 and passages 14 293 into the mandrel chamber 295. The upper body 255 under its own weight is free to move downward with the 16 mandrel 227. The cam 239 is also free to move 17 downward under its own weight as shoulder 229 moves 18 down. When cam 239 is at the bottom of cavity 240, 19 mandrel piston 297 will bear against the top of cam 239, stopping further downward movement of mandrel 227.
21 When the cam 239 is in the lower position shown in 22 Figure llb, the ring 235 will be maintained in the 23 engaged position by means of the upper lobe 241a.

When mandrel 227 is in its lower position shown 26 in Figures lla, llb, the latch ring 265 (Fig. lb) will 27 be aligned with the threads 271 in the lower body 233.
28 When this occurs, the latch ring 265 snaps outward into 29 engagement with the threads 271. The mandrel shoulder 257 will assure that the upper body 255 reaches the 31 lower position shown in Figures lla, llb.

1 When the upper body 255 is in the lower position, 2 the packoff 281 will be properly positioned in the 3 annular clearance 219 between the casing hanger 217 and 4 the wellhead 211. The upper body 255 will be latched to the lower body 233 so that it can not move upward 6 because of the latch ring 265. The mandrel piston 297 7 will be located in a lower position at the bottom of 8 the chamber 295.

The drill string is then lifted upward. The 11 upward movement of the mandrel 227 relative to the 12 upper body 255 and lower body 233 causes the mandrel 13 piston 297 to push hydraulic fluid through passage 293 14 into the setting sleeve chamber 290. Continued upward movement of the mandrel piston 297 causes a pressure 16 increase in the chambers 290, 295 and hydraulic passage 17 293. The pressure increase acts on the setting sleeve 18 piston 289.

The setting sleeve piston 289 acts on the setting 21 sleeve 275. The setting sleeve 275 applies downward 22 force to the wedge ring 279. The wedge ring 279 moves 23 downward into the cavity 283, which sets the packoff 24 281. The inner portion of the packoff 281 embeds into the casing hanger wickers 221. The outer portion of 26 the packoff 281 embeds into the wellhead bore wickers 27 215. The setting position is illustrated in Figures 28 12a, 12b. When fully set, the upper end of the setting 29 sleeve 275 will be substantially flush with the upper end of the lower body upper portion 249.

32 After testing, the running tool 225 may be 33 retrieved from the casing hanger 217. First, the drill 1 string is picked up to pull the mandrel 227 upward. At 2 a certain distance, the lug 299 (Fig. lla) will engage 3 the slot 301 as shown in Figure 13a. Then, the drill 4 string is rotated to the right again. The mandrel 227 will rotate. The lug 299 and slot 301 will cause the 6 upper body 255 to rotate with the mandrel 227. This 7 will cause the threaded ring 277 to unscrew from the 8 wedge ring 279. This rotation will also cause the 9 latch ring 265 to unscrew from the threads 271. The mandrel 227 may then be picked up.

12 As the mandrel 227 is picked up, the shoulder 229 13 will contact the lower side of the cam 239 and move it 14 up to the intermediate position shown in Figure 13b.
The threads 231a and 231b will contact the mating 16 threads in the lower body 233 to limit the upward 17 movement of the shoulder 229 to the position shown in 18 Figure 13b. The intermediate position of the cam 239 19 allows the ring 235 to retract. The entire running tool 225 may then be pulled to the surface as shown in 21 Figures 13a, 13b.

23 Referring to Figure 14, wellhead 411 will be 24 located on the subsea floor. A riser (not shown) will extend from a floating vessel down to the wellhead. A
26 casing hanger 413 is landed in the wellhead 411.
27 Casing hanger 413 will be connected to a string of 28 casing (not shown) ext~n~ing into the well. A packoff 29 415 locates in an annular space between the casing hanger 413 and the bore of the wellhead 411 to seal the 31 annulus surrounding the casing.

1 In the embodiment shown, packoff 415 has a metal 2 seal 417. A wedge ring 419 locates within an annular 3 central cavity in the seal 417. A running tool (not 4 shown) moves the wedge ring 419 downward to set the packoff 415, forcing the inner and outer walls of seal 6 417 farther apart to form a metal seal. The wedge ring 7 419 remains with the packoff 415 after the packoff 415 8 is set. It has threads or grooves 421 on its upper end 9 on the inner wall to be used in retrieving the packoff 415 at a later date.

12 A retrieving tool 423 is used to retrieve the 13 packoff 415 after it has been set. Retrieving tool 423 14 has a central, axial mandrel 425. Mandrel 425 has threads 427 on its upper end, which serve as connection 16 means for connecting the mandrel 425 to the lower end 17 of the string of conduit, such as a string of drill 18 pipe (not shown).

A mandrel piston 429 is integrally formed on the 21 mandrel 425. Mandrel piston 429 extends radially 22 outward from the mandrel 425 and has seals 431 on its 23 outer diameter. An exterior cylindrical wall 433 of 24 smaller diameter than mandrel piston 429 is formed on the mandrel 425 above the mandrel piston 429.

27 The mandrel piston 429 slidingly and sealingly 28 engages a bore 435 of a body 437. A pressure chamber 29 439 is defined by the space between the bore 435 of body 437 and the exterior wall 433 of mandrel 425. The 31 pressure area of mandrel piston 429 is the transverse 32 cross-sectional area of the mandrel piston 429. This 33 pressure area corresponds to the difference between the 1 diameter. of the bore 435 and the outer diameter of the 2 exterior wall 433.

4 Body 437 has a landing shoulder 441 on its lower end that serves as means for landing the retrieving 6 tool 423 on the upper end of the casing hanger 413.
7 Body 437 is tubular, having an exterior wall 443 that 8 is cylindrical. Seals 445 are located on the exterior 9 wall 443.
11 A retrieving sleeve piston 447 is carried by 12 mandrel 425. The retrieving sleeve piston 447 is an 13 annular member for carrying packoff 415. Retrieving 14 sleeve piston 447 has an inner diameter containing seals 449 which sealingly engage the exterior wall 433 16 of mandrel 425. A retrieving sleeve 451 is integrally 17 formed with and depends downward from the retrieving 18 sleeve piston 447. The retrieving sleeve 451 has an 19 inner cylindrical wall 453. The inner wall 453 sealingly and slidingly engages the exterior wall 443 21 of the body 437.

23 A latch means for latching into the packoff 415 is 24 carried on the outer wall of the retrieving sleeve 451.
This latch means comprises a split latch ring 455. The 26 latch ring 455 is retained on its upper end by a collar 27 457 and is located in a recess 459 on the retrieving 28 sleeve 451. The latch ring 455 has grooves on its 29 exterior adapted to latch into and engage the grooves 421 on the packoff wedge ring 419. Once engaged, the 31 retrieving sleeve 451 will be locked to the packoff 32 wedge ring 419, so that upward movement of the 1 retrieving sleeve 451 will cause upward movement of the 2 wedge ring 419.

4 The retrieving sleeve piston 447 serves as reacting means in fluid communication with the pressure 6 chamber 439 for upward movement relative to the body 7 437 in response to a pressure increase in the pressure 8 chamber 439. The retrieving sleeve piston 447 has a 9 pressure area that is greater than the pressure area of the mandrel piston 429. The pressure area of the 11 retrieving sleeve piston 447 is the transverse cross-12 sectional area that is bounded on the inner side by the 13 mandrel exterior wall 433 and on the-outer side by the 14 body exterior wall 443. The chamber 439 is filled with a substantially incompressible hydraulic fluid and 16 is sealed from the exterior of the retrieving tool 423 17 by means of the seals 431, 445, and 449.

19 A pair of stop rings 461 located on the mandrel 425 serve as a stop to limit downward movement of the 21 mandrel 425 relative to the retrieving sleeve piston 22 447 and body 437. The body 437 i8 retained with the 23 retrieving tool 423 by means of a downward facing 24 retention shoulder 463 formed on the exterior wall 443 of the body 437. The retention shoulder 463 is adapted 26 to engage a plurality of pins 465 (only one shown) 27 located on the lower end of the retrieving sleeve 451.

29 In operation, to retrieve packoff 415, the retrieving tool 423 is lowered on a string of conduit, 31 such as drill pipe. Initially, the retrieving sleeve 32 piston 447 will be located in contact with the upper 33 side of the mandrel piston 429. The body 437 will be 1 located in a lower position (not shown) with the 2 retention shoulder 463 in contact with the retention 3 pins 465. The body 437 will first land on the upper 4 end of the casing hanger 413. Continued downward movement of mandrel 425 results in the stop rings 461 6 contacting the upper end of retrieving sleeve piston 7 447. The weight of the drill string pushes down on the 8 retrieving sleeve piston 447, causing the latch ring 9 455 to ratchet into engagement with the grooves 421 of the packoff 415.

12 Then, the drill string is pulled upward. The 13 mandrel piston 429 will cause a pressure increase in 14 the hydraulic fluid. The pressure of the hydraulic fluid in the chamber 439 acts against the retrieving 16 sleeve piston 447. The piston 447 will start to move 17 upward, pulling the wedge ring 419 upward from the seal 18 417.

The pressure in the pressure chamber 439 i8 equal 21 to the upward force on the mandrel 425 divided by the 22 pressure area of the mandrel piston 429. The force 23 exerted on the packoff assembly 415 is equal to the 24 pressure in the pressure chamber 439 times the pressure area of the retrieving sleeve piston 447. For example, 26 if the pressure area of the retrieving sleeve 447 is 27 ten times that of the pressure area of the mandrel 28 piston 429, then the upward force exerted by the 29 retrieving sleeve 451 will be ten times that of the upward force pulled on the drill string. The 31 intensification of the force provides a sufficient 32 force for retrieving a metal seal packoff 415.

1 When in the uppermost position, the retrieving 2 tool 423 appears as shown in Figure 2. Continued 3 upward pulling will retrieve the entire packoff 4 assembly 415. A new packoff can then be lowered in place and set using a running tool (not shown).

7 The invention has significant advantages. A high 8 force is achieved by using the differential pistons.
9 This high force enables the setting of metal packoffs.
Annulus fluid pressure is not needed. There is no need 11 for dropping balls or darts, or to shift pins in J-12 slots in order to pump fluid down the drill pipe. The 13 running tool can be released after ~etting by pulling 14 upward and rotating in one embodiment, or by straight upward pull in the other embodiment. In another 16 embodiment, the tool is able to retrieve a metal seal 17 packoff by intensifying the actual force pulled on the 18 drill string.

Claims (21)

1. A tool (25) (225) (423) for performing an operation on a packoff (81) (281) (415) located between a casing hanger (17) (217) (413) and a wellhead (11) (211) (411), comprising in combination:

a mandrel (27) (227) (425) having means (26) (226) (427) for connection to a string of drill pipe;

a body (55) (255) (437) carried by the mandrel (27) (227) (425), the mandrel (27) (227) (425) being axially movable relative to the body (55) (255) (425);

a sleeve (75) (275) (451) carried by the body (55) (255) (437) and having means (77) (277) (455) for connection to the packoff (81) (281) (415);

a sleeve piston (89) (289) (447) in engagement with the body (55) (255) (437) for movement relative to the body (55) (255) (437) and positioned to engage an upper end of the sleeve (75) (275) (451);

a mandrel piston (97) (297) (429) carried by the mandrel (27) (227) (425) for movement therewith; and communication means (93) (293) (439) containing a fluid for communicating pressure created by axial movement of the mandrel piston (97) (297) (429) with the sleeve piston (89) (289) (447), whereby axial movement of the mandrel piston (97) (297) (429) and mandrel (27) (227) (425) relative to the body (55) (255) (437) due to axial movement of the drill string will increase the pressure of the fluid to exert an axial force on the sleeve piston (89) (289) (447) to move the sleeve (75) (275) (451) axially to perform the operation on the packoff (81) (281) (415).

2. The tool (25) (225) (423 according to claim 1 wherein the mandrel piston (97) (297) (429) has a smaller pressure area than the sleeve piston (89) (289) (447).

3. The tool (25) (225) (423) according to claim 2 wherein the communication means (93) (293) (439) is sealed from the exterior of the tool (25) (225) (423).

4. The tool (25) (225) according to claim 2 wherein the axial force exerted on the sleeve piston (89) (289) by the increase in pressure caused by the mandrel piston (97) (297) is downward in direction for moving the sleeve (75) (275) downward to set the packoff (81) (281).

5. The tool according to claim 4 wherein the communication means (93) (293) comprises:

a sleeve chamber (90) (290) within the body (55) (255), the sleeve piston (89) (289) being carried in the sleeve chamber (90) (290) for axial movement relative to the body (55) (255);

a mandrel chamber (95) (295) located between the body (55) (255) and the mandrel (27) (227), the mandrel piston (97) (297) being carried in the mandrel chamber (95) (295) for axial movement relative to the body (55) (255); and passage means (93) (293) located in the body (55) (255) sealed from the exterior of the body (55) (255) for communicating the fluid from the mandrel chamber (95) (295) with the sleeve chamber (90) (290).

6. The tool (25) (225) according to claim 5 wherein the body (55) (255) has an upper portion (55) (255) and a lower portion (33) (233) which are axially movable relative to each other, the sleeve chamber (90) (290) being located in the upper portion (55) (255) of the body, and wherein the tool (25) (225) further comprises:

retaining means (31a,b) (231a,b) for retaining the upper portion (55) (255) of the body in an upper position relative to the lower portion (33) (233) of the body while cementing the casing hanger (17) (217) in place and for moving the upper portion (55) (255) of the body from the upper position to a lower position relative to the lower portion (33) (233) of the body, with the packoff (81) (281) located between the casing hanger (17) (217) and the wellhead (11) (211), after the casing hanger (17) (217) has been cemented in place.

7. The tool (25) (225) according to claim 6 wherein the body (33,55) (233,255) has connection means (35) (235) for releasably connecting the lower portion of the body (33) (233) to the casing hanger (17) (217).

8. The tool (25) (225) according to claim 7 wherein the tool (25) (225) further comprises:

latch means (65) (265) for latching the upper portion (55) (255) of the body to the lower portion (33) (233) of the body when the upper portion ( 33) (233) of the body is in the lower position, to prevent upward movement of the upper portion (55) (255) of the body relative to the lower portion ( 33) (233) of the body.

9. The tool (25) (225) according to claim 8 further comprising release means (37, 43) (237, 243) for releasing the connection means (35) (235) from the casing hanger (17) (217) and the setting sleeve (75) (275) from the packoff (81) (281) to allow the tool (25) (225) to be retrieved after the packoff (81) (281) is set.

10. The tool (25) (225) according to claim 9 wherein the retaining means (31a,b) (231a,b) comprises:

mating threads (31a,b) (231a,b) in the mandrel (27) (227) and lower portion (33) (233) of the body for retaining the mandrel (27) (227) and the upper portion (55) (255) of the body in said upper position, and for allowing the mandrel (27) (227) and upper portion (55) (255) of the body to move downward by rotating the drill string and mandrel (27) (227) to unscrew the threads.

11. The tool (25) according to claim 9 further comprising:

a locking element (57) located in a recess (59) between the mandrel (27) and the upper portion (55) of the body, for moving the upper portion (55) of the body and sleeve (75) downward with the mandrel (27) from the upper position to the lower position; and means (63) for releasing the locking element ( 57) when the upper portion (55) of the body is in the lower position, to allow downward movement of the mandrel (27) relative to the upper portion (55) of the body for moving the mandrel piston ( 97) in the mandrel chamber (95) downward to apply pressure to the sleeve chamber (90).

12. The tool (25) (225) according to claim 11 wherein the latch means (65) (265) comprises a split latch ring (65) (265) carried by the upper portion (55) (255) of the body, and a latch groove (71) (271) located in the lower portion (33) (233) of the body for receiving the latch ring (65) (265) when the upper portion (55) (255) of the body moves to the lower position.

13. The tool (25) according to claim 12 wherein the means (63) for releasing the locking element (57) comprises pin means (63) extending through the upper portion (55) of the body and connecting the latch ring (65) with the locking element (57), for causing the locking element (57) to move out of the recess (59) when the latch ring (65) engages the latch groove (69).

14. The tool (25) (225) according to claim 7 wherein the connection means (35) (235) comprises:

an engaging element (35) (235) carried by the lower portion (33) (233) of the body, and movable between an inner retracted position and an outer engaged position in engagement with a groove (23) (223) in the casing hanger (17) (217), for securing the lower portion (33) (233) of the body to the casing hanger (17) (217);

a cam (39) (239) carried by the mandrel (27) (227) in the lower portion (33) (233) of the body for axial movement relative to the lower portion (33) (233) of the body between an engaging position and a released position, the cam (39) (239) forcing the engaging element (35) (235) outward to the engaged position when the cam (39) (239) is moved to the engaging position.

15. The tool (25) according to claim 2 wherein the axial movement of the drill string to move the mandrel piston (97) to increase the pressure of the fluid is in a downward direction.

16. The tool (225) according to claim 2 wherein the axial movement of the drill string to move the mandrel piston (297) to increase the pressure of the fluid is in an upward direction.

17. The tool (423) according to claim 2 wherein the axial force exerted on the sleeve piston (447) by the increase in pressure caused by the mandrel piston (429) is upward in direction for moving the sleeve (451) upward to retrieve the packoff (415).

18. The tool (423) according to claim 17 wherein the means (455) for connection of the sleeve (451) to the packoff (415) comprises a latch (455) which latches to the packoff (415) when the sleeve (451) is lowered into contact with the packoff (415).

19. The tool (423) according to claim 17 wherein the sleeve (451) depends from the sleeve piston (447) and has an inner wall (453) that sealingly and slidingly engages an exterior wall (443) of the body (437).

20. The tool (423) according to claim 17 wherein the sleeve piston (447) has a lower portion that is in communication with the fluid in the communication means (439).

21. The tool (423) according to claim 17 wherein:

the mandrel (425) and the body (437) each has an exterior wall (433,443) and the body (437) has a bore (435);

the mandrel piston (429) extends radially outward from the exterior wall (433) of the mandrel (425) and has an outer diameter sealingly engaging the bore (435) of the body (437), the mandrel piston (429) having a pressure area defined by the difference in diameter between the exterior wall (433) of the mandrel (425) and the bore (435) of the body (437);

the sleeve piston (447) has an inner diameter that sealingly and slidingly engages the exterior wall (433) of the mandrel (425) above the mandrel piston (429);

the sleeve (451) depends from the sleeve piston (447) and has an inner wall (453) that sealingly and slidingly engages the exterior wall (443) of the body (437), the sleeve piston (447) having a pressure area that is greater than the pressure area of the mandrel piston (429) and which is defined by the difference in diameter between the exterior wall (433) of the mandrel (425) and the exterior wall (443) of the body (437);
and the communication means comprises a chamber (39) between the mandrel piston (429) and the sleeve piston (447).