WELL ABANDONMENT AND SLOT RECOVERY

The present invention relates to methods and apparatus for well abandonment and slot recovery and in particular, though not exclusively, to a method of removing a wellhead and cut conductor and to a recovery assembly including a self-re-cocking jacking tool to aid such removal.

A typical oil or gas well is equipped with an inner production tubing positioned within one or more concentric strings of pipe or well casing which in turn are surrounded by a large-diameter pipe string, known as a well conductor which extends from surface to several hundred feet into the earth formation. The well conductor generally supports the weight of the wellhead and at least a portion of the weight of the strings of tubing and casing hung in the well. The well conductor also protects the inner pipe strings from corrosion.

During the abandonment of oil and gas wells it is sometimes necessary to remove wellhead equipment by cutting the well conductor casing a distance below the surface. The wellhead together with the cut conductor are then lifted from the earth formation. In certain locations such as shallow water and swamp areas, the force required to remove the wellhead and cut conductor is higher than the surface equipment can supply; for instance when there is a barge with a crane available. Often it is uneconomical to bring a rig on station to accomplish the process.

In removing casing strings for abandonment it is known to use a downhole power tool (DHPT) to fish a cut section of casing as described in WO2018/083473 to Ardyne Holdings Limited and GB2533022 to Weatherford Technology Holdings LLC, the contents of which are incorporated herein in their entirety by reference. After the casing has been cut and engaged with a casing spear, hydraulically-set mechanically releasable slips anchor the DHPT to the wall of the larger diameter outer casing above. A static pressure is applied to begin the upward movement of the cut casing, with the DHPT downhole multi-stage hydraulic actuator functioning as a hydraulic jack. After the stroke is completed, the anchors are released. The power section can be reset, by raising the DHPT relative to the cut section of casing, and the anchor re-engaged as many times as required. The DHPT is described in US 8,365,826 to Ardyne Holdings Limited, the disclosure of which is incorporated herein in its entirety by reference. As the DHPT must be anchored to an outer casing above to operate, this arrangement cannot be used to raise a conductor and wellhead.

US 9,650,853 to Baker Hughes Incorporated discloses a cutting and jacking system which allows a cut section of casing to be separated from the remaining casing string without requiring the outer casing for support. The downhole tool may include an upper slip and a lower slip configured to selectively engage casing of a wellbore. A cutter and an extendable section may be positioned between the upper and lower slips. The cutter may be used to cut casing into an upper portion and a lower portion and the extendable section may be used to increase a distance between the upper and lower slips that moves the upper portion of the casing and the lower portion of the casing away from each other. The extendable section may be hydraulically actuated to move the upper portion of the casing away from the lower portion of the casing. The cutter may be an abrasive jet configured to cut the casing. This arrangement is limited in that the cut section of casing can only be raised by the length of the extendable section.

It is therefore an object of the present invention to provide a method of removing apparatus from a well obviates or mitigates one or more disadvantages of the prior art. It is a further object of at least one embodiment of the present invention to provide a method of removing a cut well conductor and wellhead from a wellbore which obviates or mitigates one or more disadvantages of the prior art.

It is a further object of at least one embodiment of the present invention to provide a recovery assembly including a jacking tool for removing a cut well conductor and wellhead from a wellbore which obviates or mitigates one or more disadvantages of the prior art.

According to a first aspect of the present invention there is provided a method for removing apparatus from a well, comprising the steps:

(a) suspending a recovery assembly from a work string, the recovery assembly comprising a jacking tool and an anchoring device, the jacking tool being arranged below the anchoring device;

(b) running the recovery assembly into a well to locate a gripping mechanism of the jacking tool at tubing in the well;

(c) anchoring the anchoring device to the apparatus;

(d) activating the jacking tool to grip the tubing ;

(e) activating the jacking tool to apply an upward force to the anchoring device while stroking the jacking tool so that the anchoring device and the apparatus is lifted upwards away from the jacking tool;

(f) disengaging the jacking tool from the tubing; and

(g) pulling the apparatus free of the well.

In this way, the additional force which can be applied by the jacking tool as compared to the force available on pulling the work string can be used to free the apparatus from the well. By locating the jacking tool on tubing below the apparatus, the jacking tool can be anchored to any tubing in the well and is not limited to a need for an outer casing string to be present. By jacking upwards a pushing force is applied to the apparatus, with the jacking tool working in a reverse configuration.

The method may include the step of running a cutting tool in the well to cut the tubing and at step (d), the jacking tool grips tubing below a cut point. In this way, a cut section of casing can be removed.

The anchoring device may be a casing spear. The apparatus may be a cut section of casing. In an embodiment the apparatus is a well conductor The well conductor is a surface casing or conductor casing. The well conductor may be connected to a wellhead and the apparatus includes the wellhead. In this way, the wellhead can be pulled from the well together with the well conductor. In an embodiment, the anchoring device is a wellhead picker. In this way, the wellhead is supported on removal.

Advantageously, steps (d) to (f) are repeated after step (f) until the apparatus is free and can be pulled from the well. In this way, the use of the jacking tool is not limited to a single stroke as in the prior art. This allows a repeated force to be applied to the apparatus.

Preferably, the method includes the step of resetting the jacking tool at step (f) once the jacking tool has been disengaged from the tubing . The step of resetting the jacking tool will return to jacking tool to the start of the stroke in preparation to make the next stroke to move the anchoring device upwards away from the jacking tool. This may be considered as re cocking the jacking tool.

The work string may be selected from a group comprising : drill pipe, tubing, slickline, wireline, craneline and chain. In this way, any convenient arrangement may be used to suspend the recovery assembly at a well and recover a wellhead. Preferably, the method includes hoisting the work string at step (g). In this way the hoist is used to support the recovery assembly at step (c). This allows the method to be used without requiring a rig and thus is adaptable to be used from a floating vessel such as a barge with a crane.

The method may include the step of cutting the tubing at the cut point. The step of cutting the tubing may be on the same trip into the well. This allows the tubular to be cut and pulled on a single trip. Alternatively, the step of cutting the tubular can be made on a separate trip into the well.

According to a second aspect of the present invention there is provided a recovery assembly for removing apparatus from a well, the recovery assembly being configured to be suspended on a work string for running into the well, the recovery assembly including :

an anchoring device to attach the assembly to the apparatus for recovery thereof;

a jacking tool, the jacking tool comprising :

an inner mandrel having a bore and an outer housing;

an anchor section including one or more slips for axially fixing the jacking tool to tubing in the well;

a power section including an axially stacked plurality of pistons generating a cumulative axial force on the anchoring device, the plurality of pistons arranged between the inner mandrel and the outer housing and axially movable by a stroke length relative to the one or more slips in response to the fluid at a first pressure in the bore; and

a resetting mechanism to move the plurality of pistons back across the stroke length. Existing downhole jacking tools are re-set or re-cocked by lifting the pipe string connecting the jacking tool to surface. The jack is thus stroked in the opposite direction to that during activation by hydraulic pressure. For the present invention, this operation cannot be used as the movement of the pistons is used to create the lift in the pipe string.

Preferably, the jacking tool is arranged with the power section between the anchoring device and the anchor section. In this way, if both the anchoring device and anchor section are set to grip the apparatus and tubing respectively, the cumulative axial force will act against the anchoring device. Preferably the anchoring device is a casing spear. Alternatively, the anchoring device may be a wellhead picker. Those skilled in the other will recognise that there are other tools of known type capable of attachment to the conductor or to the wellhead to lift these.

In an embodiment, the resetting mechanism comprises a biasing means to bias the pistons in a direction back across the stroke length. In this way, the fluid pressure in the bore is required to overcome the bias in order to operate the jacking tool when the slips are set to grip the tubing. When the slips are unset and the fluid pressure in the bore reduced the biasing means will move the pistons back across the stroke length. In use, if the jacking tool cannot complete a stroke to move the apparatus, the resetting mechanism will move the pistons back across a distance equal to the distance travelled by the cut section of tubing, being a portion of the stroke length. This can be considered as a re-cocking mechanism. Preferably, the biasing means is a spring. Advantageously, the spring is a pre-compressed spring which extends when the hydraulic pressure of the fluid in the bore is released. More preferably, the spring is located between a piston and a stop in the jacking tool. Alternatively, the resetting mechanism is located in a separate adaptor to the jacking tool.

In an alternative embodiment, the resetting mechanism is a chamber located between the inner mandrel and the outer housing, having access to a reverse side of a piston, and a hydraulic control line. The resetting mechanism operates when fluid pressure in the bore is stopped, fluid under pressure is introduced to the chamber via the hydraulic control line to act on the reverse side of the piston and move the pistons back to their original positions at the other end of the stroke.

In a preferred embodiment, the plurality of pistons are arranged on the inner mandrel, with the inner mandrel axially moveable relative to the one or more slips and being connected to the anchoring device; the outer housing surrounds the inner mandrel and includes a plurality of stops, spaced apart a distance over which each piston can travel the stroke length, and the housing supports the anchor section. In this way, setting the anchor fixes the housing axially in the tubing, fluid pressure from the bore of the inner mandrel can be directed to act on the pistons to move them between the stops and thereby move the inner mandrel and hence the anchoring device upwards away from the anchor section. In this embodiment the anchor section may be located at either end of the outer housing, though preferably is at a lower end, in use. In an alternative embodiment, the plurality of pistons are arranged on the inner wall of the outer housing, the outer housing being connected to the anchoring device and axially moveable relative to the one or more slips, the housing surrounds an inner mandrel including a plurality of stops mounted thereon, spaced apart a distance over which each piston can travel the stroke length, the inner mandrel extending from a lower end of the housing and supporting the anchor section thereon. Operation is the same via fluid from the inner mandrel entering a sealed chamber between each piston and stop to cause the pistons to move over the stroke length. The recovery assembly may further include a cutting tool. The cutting tool may be a casing cutter as is known the art for creating a 360 degree cut in tubing to sever an upper portion of tubing from a lower portion of tubing in a well. The tubing may be a well conductor. The cutting tool may be located below the jacking tool on a distal end of the recovery assembly. Alternatively, the cutting tool may be located between the anchoring device and the jacking tool.

The recovery assembly may include further tools as are known in the art such as a positive displacement motor for turning the cutting tool and/or a valve for closing the bore to allow fluid pressure to build up in the jacking tool.

In an embodiment, the work string is a tubular being co-linear with the bore of the jacking tool. In this way fluid from surface can be used to operate the tool. In an alternative embodiment, the work string is a chain or other line and the recovery assembly includes a hydraulic fluid line to deliver fluid under pressure to the bore.

In the description that follows, the drawings are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including," "comprising," "having," "containing," or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. All numerical values in this disclosure are understood as being modified by "about". All singular forms of elements, or any other components described herein including (without limitations) components of the apparatus are understood to include plural forms thereof. While phrases such as 'up', 'down', 'upper' and 'lower' are used these are considered to be relative and the invention can be used in deviated wells and is not limited to use in vertical wells.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings of which:

Figures 1(a) to 1(g) illustrate a method of removing apparatus from a well according to an embodiment of the present invention; Figures 2(a) to 2(c) illustrate a recovery assembly according to an embodiment of the present invention illustrating operating modes of a jacking tool;

Figure 3 illustrates a jacking tool of a recovery assembly according to a further embodiment of the present invention;

Figures 4(a) to 4(d) illustrate a jacking tool of a recovery assembly according to a further embodiment of the present invention, in operating modes at figures 4(a) to 4(c) together with an exploded view of a resetting mechanism at Figure 4(d); Figures 5(a) to 5(c) illustrate a method of removing a wellhead and well conductor from a well according to an embodiment of the present invention; and Figures 6(a) and 6(b) are schematic illustrations of recovery assemblies according to further embodiments of the present invention.

Reference is initially made to Figures 1(a) to 1(g) of the drawings which illustrate a method for removing apparatus from a well, according to an embodiment of the present invention. Figure 1(a) shows a well 10 in which a tubing 12 is located. In the example shown tubing 12 is a surface casing being a well conductor 14 which extends from a surface 16 into formation 18. At the surface 16, there is a wellhead 20, as is known the art, supported on the well conductor 14. It is desired to remove the wellhead 20 and a portion of the well conductor 14 to a position below the mudline (not shown). The first step is to cut the tubing 12 at the required depth by a known method. This is illustrated in Figure 1(b) where the well conductor 14 has been severed at a cut point 22, to provide a cut section of tubing 24 separate from the remaining tubing 26. The well conductor may be cut by any known means such as by rotating knives, chemical action, water jetting, laser cutting, or milling. In this example the cutting step is shown as being carried out on a separate trip into the well 10. Flowever, the cutting step may be completed on the same trip into the well as the remaining method steps if the cutting tool where incorporated into the recovery assembly 30, used for the removal of the cut section of tubing 24.

We now require to economically remove the wellhead 20 and cut conductor 28. The recovery assembly 30 may be considered as a bottom hole assembly. Assembly 30 is run in the well 10. The assembly 30 comprises, from a first end 32, a jacking tool 34, on a pipe string 36 with an anchoring device 38 located in the string 36 above the jacking tool 34. The pipe string 36 is supported at the surface 16 by a crane hoist 40. The crane hoist 40 may be located on a floating vessel such as a barge (not shown). The jacking tool 34 will be described hereinafter with reference to Figures 2(a) to (c). The jacking tool 34 may be considered as a downhole hydraulic jack which includes an anchor mechanism 42 for latching to an inner surface 44 of the tubing 12. The anchoring device 38 is a casing spear. In other embodiments the anchoring device 38 may be a wellhead latch or another tool of known type capable of attachment to the conductor or to the wellhead. The anchoring device 38 includes slips 46 or other anchor mechanism to grip the inner surface 44 of the tubing 12.

The assembly 30 is run into the well 10 such that the jacking tool 34 is positioned below the cut point 22 on the remaining casing 26 and the anchoring device 38 is positioned above the cut point 22 on the cut conductor 28. This is as illustrated in Figure 1(c) with the assembly 30 being supported by the crane hoist 40. The wellhead 20 may also be supported at surface 16. Other hoisting equipment may be used, such as a derrick if a rig is used. Once in position the anchoring device 38 is anchored to the inner surface 44 of the tubing 12 above the cut point 22 via the slips 46.

Next the jacking tool 34 is activated to initially grip the inner surface 44 of the tubing 12 at a position below the cut point 22. The jacking tool 34 then applies an upward force to the anchoring device 38, by stroking the jacking tool 34, so that the anchoring device 38, wellhead 20 and cut conductor 28 are raised upwards. The distance between the anchoring device 38 and jacking tool 34 is increased by a stroke length of the jacking tool 34. This is as illustrated in Figure 1(d). If the cut conductor 28 and wellhead 20 are free of the grip of the formation 18 they may be hoisted via the crane hoist 40 to surface 16 and removed from the well 10. However, as the stroke length on jacking tools is limited, it is possible that the wellhead 20 and cut conductor 28 may require more than one stroke of the jacking tool 34 to release it from the grip of the earth formation 18 until the hoisting equipment 40 is capable of pulling it from the ground. In this case the downhole jacking tool 34 can be re-set i.e. 're-cocked' whilst in the well 10. Existing downhole jacks are re-cocked by lifting the pipe connecting the jack to surface. The jack is thus stroked in the opposite direction to that during activation by hydraulic pressure. For the procedure of the present invention, this operation cannot be used to re-cock the jacking tool 34, as the jacking tool is below the anchoring device 38 in the well 10 which is set to hold the cut tubing 12 and therefore cannot be lifted by the pipe string 36 from surface 16. The jacking tool 34 of the present invention includes means to re-cock itself when hydraulic pressure is released. This is as described with reference to Figures 2(a) to (c). The jacking tool 34 is re-cocked by stopping pumping fluid down a bore 64 of the pipe string 36 and releasing the anchor mechanism 42 so that the jacking tool 34 releases from the remaining tubing 26. This effectively de-activates the jacking tool 34 and allows it to reset so that the distance between the anchoring device 38 and the jacking tool 34 returns to the initially separation on run-in, as shown in Figure 1 (e). The jacking tool 34 has been raised from its initial position (see Figure 1(c)).

The jacking tool 34 is then re-activated to engage the anchor mechanism 42 again and stroke to lift the wellhead 20 and cut conductor 28, as described for Figure 1(d). This is as illustrated in Figure 1(f). The jacking tool 34 can be stroked and re-cocked any number of times until the crane hoist 40 is capable of lifting the wellhead 20 and cut conductor 28 to surface 16. Once the wellhead 20 and cut conductor 28 are removed the well 10 is left with the remaining tubing 26 in place and further steps to abandon the well 10 can be undertaken. This is illustrated in Figure 1(g). The ability to re-cock the jacking tool 34 in the well 10 advantageously allows the cut section of tubing 24, to be forced upwards over distances greater than the stroke length of the jacking tool 34 used. This means that in the method of the present invention: it can be carried out on a single trip into the well 10; the well conductor 14 can be cut at increased depths; and, the wellhead 20 need only be supported by the crane hoist 40 throughout.

A self re-cocking jacking tool 34 is shown in Figures 2(a) to 2(c). Like parts to those of Figure 1 will be given the same reference numerals to aid clarity. Figure 2(a) shows a schematic illustration of the assembly 30 with the anchoring device 38 latched to the inner surface 44 of the cut tubing 24, and the jacking tool 34 with its anchor mechanism 42 also latched to the inner surface 44 of the remaining tubing 26. The jacking tool 34 has most of the standard parts found in a downhole hydraulic jack. Downhole hydraulic jacks have been used in the oilfield for many years. They are often provided with an anchor mechanism for latching to a piece of sub-surface casing and hydraulic pistons which when pressurised pull or push an object in the desired direction from above. Often there are multiple pistons to magnify the force. In the jacking tool 34 these are shown as an anchor section 42 and a power section 48. The anchor section or anchor mechanism 42 comprises slips 52 which are moved radially outwards, typically by being driven over cones, to engage the inner surface 44 of tubing 12. The power section 48 includes a series of stacked pistons 50a-d to provide the cumulative force to move the pipe 36 attached to the cut tubing 24. In the arrangement shown in Figure 2(a) the pistons 50a-d, are arranged on an inner mandrel 54 which is connected at its upper end 56 to the pipe string 36. A housing 58 is arranged around the inner mandrel 54 which sealingly engages the inner mandrel 54 via sliding seals so that the inner mandrel 54 can move axially relative to the housing 58. Inside the housing are stops 60a-e which extend from the inner wall 62 of the housing to the inner mandrel 54 and have sliding seals therebetween. A piston 50a is arranged between each pair of stops 60a, b so that its travel is limited to that of the stroke length of the jacking tool 34. The pistons 50a-d have sliding seals onto the inner wall 62 of the housing 58 so that fluid passed through ports from a bore 64 of the inner mandrel 54, to the sealed chamber between a piston 50a and a stop 60b, will cause the piston 50a, to travel to the upper stop 60a. Exhaust ports are provided on the underside of the stops 60a-d through housing 58. Although the arrangement is shown with four pistons, the number and surface area of each is selected dependent upon the force required to be produced.

A re-cocking arrangement 70 is shown in the jacking tool 34. This provides a biasing element, which in the embodiment shown is a spring 66. The spring 66 is arranged between a piston 50d and a stop 60d.

Spring 66 is pre-compressed so that the piston 50d is biased towards the stop paired stop 60e, so that the pistons 50 are biased towards a starting position to begin a stroke and operate the jacking tool 34. The spring 66 therefore holds the pistons 50a-d against the lower stops 60b-e.

In use, the assembly 30 is run into the well 10 through the tubing 12. Depending upon the mass of the housing 58 balanced against the force of the spring 66, the pistons 50 may move between the stops 60. This will be seen as movement of the housing 58 over the inner mandrel 54 but does not affect operations. Once the jacking tool 34 is in position with the anchor mechanism 42 below the cut point 22, the string 36 is stopped. The spring 66 now biases the pistons 50a-d against the lower stops 60b- e. The anchoring device 38 on the assembly 30 above the jacking tool 34, positioned above the cut point 22 can now be set to grip the cut section of tubing 24. The anchor mechanism 42 on the jacking tool 34 is then set against the remaining tubing 26. The anchor mechanism 42 is arranged on the housing 58 and may be above (see Figure 1(c)) or below (see Figure 2(a)), the power section 48. Typically, a valve or other pressure drop facility will be mounted on the string 36 below the jacking tool 34. This will be used to increase fluid pressure in the bore 64 of the jacking tool 34 to hydraulically operate the anchor mechanism 42 and the power section 48. This is as illustrated in Figure 2(a).

As fluid from the bore 64 enters the ports and acts on the underside of the pistons 50a-d, this will want to move the inner mandrel 54 upwards relative to the static housing 58. Movement will occur when the fluid pressure causes a force greater than that of the spring 66 which is acting against it. This applied pressure on the pistons 50a-d jacks the cut tubing 24 upwards as the inner mandrel 54, is forced against the anchoring device 38 attached to the cut section of tubing 24. This is as illustrated in Figure 2(b), where the casing sections 24, 26 are seen to separate and a distance is formed between them. The pistons 50a-d can travel a stroke length between the stops 60a-e, which translates to the distance the cut section 24 can be moved.

To re-cock the jacking tool 34 and allow the tool 34 to re-set and jack again, fluid pressure in the bore 64 is reduced and the slips 52 on the anchor mechanism 42 unset. Note that the anchoring device 38 remains set. The spring 66 will now at between the stop 60d and the piston 50d so as to move the housing 58 upwards and bring the pistons 50 back over the stroke length, relative to the housing 58, to the initial starting position again. The jacking tool 34 has moved upwards in the tubing 12. This is as illustrated in Figure 2(c). The anchor mechanism 42 can be re-engaged and the jacking operation repeated as per Figures 2(a) to 2(c). In this way, multiple jacking operations can be carried out until the hoisting equipment 40 is capable of lifting the cut section of tubing 24, wellhead 20 and surface conductor 28 in an embodiment, clear of the ground. Figure 3 illustrates an alternative design of jacking tool, indicated by reference numeral 34'. Like parts to those of Figures 2(a) to (c) are given the same reference numeral to aid clarity. Here the housing 58' is attached to the pipe string 36' above and includes the pistons 50'. The inner mandrel 54' can move within the bore 64', relative to the housing 58', and includes the stops 60'. The anchor mechanism 42' is now arranged on the inner mandrel 54' which exits the lower end of the housing 58'. The re-cocking arrangement 70' is still present and acts as before, but with the housing 58' now forcing the pipe string 36' upwards to act on the anchoring device 38' and cut section of tubing 24'.

Reference is now made to Figures 4(a) to 4(d) illustrating a further alternative design of jacking tool, indicated by reference numeral 234. Like parts to those of Figures 2(a) to (c) are given the same reference numeral with the addition of 200 to aid clarity. Jacking tool 234 has an anchor section 242 and power section 248 as for the jacking tool 34, shown in Figures 2(a) to 2(c). However, an alternative resetting mechanism 270 is used. In the jacking tool 234 the bore 264 does not lead to a pipe string, but instead terminates at a connection plate 35. A hydraulic pressure line (not shown) is connected to a port 37 in the plate 35. The resetting mechanism is formed as a hydraulic control line 39 which is also connected to the plate 35 and runs through the body 41 of the inner mandrel 254, parallel to the bore 264. The hydraulic control line 39 connects to a chamber 41 behind a piston 250a. The hydraulic control line 39 may connect to a single chamber 41 or may connect to chambers at each piston. Chamber 41 is a chamber created at the reverse side 43 of the piston 250a to the sealed chamber 45, between a piston 250a and a stop 260a, through which fluid enters from the bore 264, via ports 47 to activate the jacking tool 234. See Figure 4(d). Activation of the jacking tool 234 is as described with reference to Figures 2(a) to (c) with fluid from a hydraulic pressure line entering the bore 264, see Figure 4(b). The lower end of the bore 264 is sealed 49 to allow the build-up of pressure in the bore 264 to activate the tool 234. When the tool 234 has stroked, Figure 4(a), fluid injected down the hydraulic control line 39 will fill the chamber 41 and cause the piston 250a, to move back towards the stop 260a, Figure 4(c). The jacking tool 234 is thus placed in its original configuration to be activated again.

Use of the jacking tool 234 for removing a wellhead 20 and well conductor 14, from a subsea well will now be described with reference to Figures 5(a) to 5(c). Like parts to those in Figures 1(a) to 1(g) are given the same reference numeral with the addition of 200 to aid clarity. Jacking tool 234 is connected to a wellhead picker 51 via the connection plate 35. The wellhead picker 51 is a known device for latching or connecting onto wellheads and acts as the anchoring device 238 in the assembly 230 with the jacking tool 234. The wellhead picker 51 also includes a hot stab for connecting hydraulic fluids to port 37 and the hydraulic control line 39. The casing conductor 214 is pre-cut at cut point 222. The following steps are then undertaken:

1. Lower jacking tool 234 into casing 214 using hoist (w/hydraulic line), coil tubing or drill pipe;

2. Ensure space-out between top of wellhead 220/casing 214 and jacking tool 234 is enough to position anchor mechanism 242 below the cut point 222. This is as illustrated in Figure 5(a);

3. Pick up and engage the recovery assembly 230 in top of wellhead 220/casing 214, so that the wellhead picker 51 anchors to the wellhead 220;

4. Take an overpull on the hoist, coil tubing or drill pipe to keep the wellhead 220/casing 214 straight during the jacking operation; 5. Stab ROV (Remotely Operated Vehicle) 53 into wellhead picker 51. The ROV 53 having hot stab 55 and pump capacity is used pressure up bore 264, by a controlled volume of fluid;

6. The jacking tool 234 will automatically activate, the anchor mechanism 242 will engage the casing below the cut point 222 and begin pushing on the wellhead picker 51 forcing the wellhead 220 out of hole;

7. Monitor the overpull on the craneline to verify the movement of the wellhead 220;

8. Once the jacking tool 234 has reached its full stroke an increase in pressure will be observed. This position is as illustrated in Figure 5(b);

9. Bleed off the hydraulic pressure to the bore 264;

10. Pressure up the hydraulic control line 39 for deactivation and reset the jacking tool 234 if a second operation is required to free wellhead 220 from the seabed 57;

11. The jacking tool 234 will retract the slips on the anchor mechanism 238 and return to start position;

12. Repeat the operation to jack the wellhead 220/casing 214 out of hole, or friction is low enough to be pulled free with the vessel crane; and

13. Pull out of hole/seabed with well head 220/casing 214 using vessel crane. This is as illustrated in Figure 5(c). The wellhead 220 and casing conductor 214 can be removed from the assembly 230 and the jacking tool 234 redressed for further operations.

Reference is now given to Figures 6(a) and 6(b) which show schematic illustrations of assemblies 30, which could be used to provide cutting of the tubing 12 on the same trip into the well 10 as that of removing the cut section of tubing 24. Like parts to those of Figures 1(a) to 1(g) have been used to aid clarity. In Figure 4(a), a cutting tool 68 is mounted below the jacking tool 34. On run-in the cutting tool 68 can be operated with the anchor mechanism 42 of the jacking tool 34 set to provide stability, if desired. A motor may be located between the cutting tool 68 and jacking tool 34 if the cutting tool 68 is to be operated by rotation. Once the cut is made, the assembly 30 is positioned so that the anchoring device 38 is above the cut point 22 and the jacking tool 34 is below it.

Referring to Figure 6(b), the cutting tool 68 is positioned between the anchoring device 38 and the jacking tool 34. In this arrangement, anchoring device 38 and/or anchor mechanism 42 can be set when the cut is made. Advantageously, the assembly 30 does not have to be repositioned after the cut point 22 is created however, jacking of the cut section of tubing 24 must occur through the cutting tool 68. If the cutting tool 68 is hydraulically operated this may limit the fluid pressure available to operate the jacking tool 34. Where the tubing 12 is to be a wellhead 20 and well conductor 14, due to the short distance to surface 16, it may be a simpler operation to run a separate string to initially cut the conductor 14. The principle advantage of the present invention is that it provides a method of removing apparatus from a well bore by jacking without the need for an outer casing section to support the jacking tool above the apparatus. A further advantage of the present invention is that it provides a cost effective method of removing a wellhead and cut conductor from a well.

A further advantage of at least one embodiment of the present invention is that it provides a recovery assembly for removing apparatus from a well with a resettable jacking tool so that the apparatus can be moved by distances greater than the stroke length of the jacking tool in the well. Modifications may be made to the invention herein described without departing from the scope thereof. For example, while the re-cocking arrangement is shown in the power section of the jacking tool, it could be in a separate adaptor. While the tubing is described as a well conductor it may be any tubular found in a well such as production tubing, liner or casing. Features of each embodiment may be combined with features of alternative embodiments.