SUBSEA STROKING TOOL

TECHNICAL FIELD

[0001]The present invention relates to the field of subsea oil or gas production, and more specifically to a subsea stroking tool. The invention also relates to a well control package comprising the subsea stroking tool. The invention finally relates to a method of use of the subsea stroking tool for setting or recovering a plug comprised in the tubing hanger of a subsea well, or in other applications such as milling and hydrate removal.

TECHNICAL BACKGROUND

[0002]During construction of subsea production and injection wells, prior to the installation of the subsea tree on the wellhead, a blowout preventer (BOP) is put on top of the wellhead. There is a need to temporarily suspend the well, to allow removal of the BOP. Once the well has been safely obstructed, the BOP is removed so that the tree can be installed on top of the wellhead, and the production or the injection can begin.

[0007]All these existing solutions consist in providing a long hydraulic piston to stroke more than 6 meters deep to reach down through a subsea tree to set or recover a slickline plug for a vertical Christmas tree (VXT) or a crown plug for a horizontal Christmas tree (HXT). The main problem is that there is a high risk of leak along the entire stroke length of this long piston mandrel.

[0008]Within this context there is still a need for an improved solution to set or recover a plug in a tree with reduced leak risks.

SUMMARY OF THE INVENTION

[0014]In some variations, the rod has a retracted position, an extended position, and an intermediate position between the retracted position and the extended position, and wherein the set of rollers is configured to move the rod between the retracted position and the intermediate position, and the hydraulic piston assembly is configured to move the rod between the intermediate position and the extended position.

[0015]In some variations, the set of rollers is configured to be actuated by a ROV.

[0016]In some variations, the hydraulic piston assembly is configured to be actuated by a ROV.

[0022]In some variations, the hydraulic piston comprises at least a distal portion closest to the rod and a proximal portion farthest from the rod, wherein the distal portion has a smaller cross section orthogonal to the longitudinal axis than the proximal portion; and, preferably, the hydraulic piston comprises an intermediate portion between the distal portion and the proximal portion, wherein the intermediate portion has a smaller cross section orthogonal to the longitudinal axis than the proximal portion and a larger cross section orthogonal to the longitudinal axis than the distal portion.

[0023]In some variations, the hydraulic piston comprises a blind hole extending along the longitudinal axis from the proximal end thereof.

[0024]In some variations, the rod is slidable within the hydraulic piston (instead of being attached to the hydraulic piston).

[0025]In some variations, the rod comprises a proximal shoulder and the hydraulic piston comprises a plurality of load segments having a locked position and an unlocked position, the rod and hydraulic piston being configured such that the load segments may engage with the proximal shoulder when the load segments are in the locked position, and the rod may freely slide within the hydraulic piston when the load segments are in the unlocked position.

[0026]In some variations, the subsea stroking tool further comprises a connecting element attached to the distal end of the rod).

[0027]In some variations, the subsea stroking tool further comprises an end tool attached to the connecting element, said end tool preferably being configured to set or to recover a plug inside a tubing hanger of a subsea well.

[0028]The invention further relates to a well control package configured to be placed on top of a subsea tree, comprising the subsea stroking tool as described above.

[0029]The invention further relates to a method of operating the subsea stroking tool as described above, comprising a step of moving the rod along the longitudinal axis by actuating the set of rollers and a step of moving the rod along the longitudinal axis by actuating the hydraulic piston assembly.

[0030]In some variations, the method comprises a step of moving the rod distally along the longitudinal axis by actuating the set of rollers, followed by a step of moving the rod distally along the longitudinal axis by actuating the hydraulic piston assembly.

[0031]In some variations, the method comprises a step of moving the rod proximally along the longitudinal axis by actuating the hydraulic piston assembly followed by a step of moving the rod proximally along the longitudinal axis by actuating the set of rollers.

[0040]In some variations, the method further comprises injecting fluid before moving the rod.

[0041]The invention relates to a subsea stroking tool which provides an improved solution for manipulating an object, and in particular a plug, within a wellhead. In particular, no riser is required to set or recover a plug owing to this subsea stroking tool. In other words, the present invention allows for a riser-less intervention.

[0042]The invention also removes the need for a long piston: only a short piston can be used, owing to the presence of the set of rollers.

[0043]Traditional solutions, typically with a rig are extremely costly, whereas the subsea stroking tool only requires the use of construction vessels used to install the subsea tree, which significantly lowers the cost and affords major drilling expense savings.

[0044]The subsea stroking tool is also preferably air freightable, simpler in use than previous solutions and reliable with existing shear and sealing capabilities.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045]FIG. 1A/1B schematically show the internal structure of the subsea stroking tool positioned on a wellhead, according to a particular embodiment, respectively in the extended position and in the retracted position.

[0046]FIG. 2A/2B schematically show the internal structure of the subsea stroking tool according to a particular embodiment, respectively in the intermediate position and in the retracted position. The vertical scale is different in FIGS. 2A and 2B.

[0047]FIG. 3A/3B/3C/3D are various schematic views of the internal structure of part of the subsea stroking tool, according to a particular embodiment. The cutaway view of FIG. 3B corresponds to a 90° rotation of the cutaway view of FIG. 3A. FIG. 3C is another cutaway view similar to FIG. 3A, showing another part of the tool. FIG. 3D is a perspective view.

[0048]FIG. 4 schematically shows the internal structure of a part of the subsea stroking tool, according to a particular embodiment, focusing on the set of rollers.

[0049]FIG. 5 schematically shows the subsea stroking tool positioned on a wellhead and operated by a single remotely operated underwater vehicle (ROV), according to a particular embodiment.

[0050]FIG. 6A/6B schematically show the hydraulic piston of the subsea stroking tool, according to a particular embodiment, respectively in the extended position and in the retracted position.

[0051]FIG. 7A/7B/7C/7D are various schematic views of the internal structure of part of the subsea stroking tool, according to a particular embodiment, in various configurations.

DETAILED DESCRIPTION

[0052]The invention will now be described in more detail without limitation in the following description.

General Outline of the Subsea Stroking Tool

[0053]An object of the present invention is a subsea stroking tool having a longitudinal axis and comprising a housing. The subsea stroking tool comprises a hydraulic piston assembly. The subsea stroking tool further comprises a rod having a proximal end and a distal end, at least partially arranged within the housing and movable along the longitudinal axis relative to the housing. The subsea stroking tool finally comprises a set of rollers engaged with the rod. In the subsea stroking tool, both the set of rollers and the hydraulic piston assembly are configured to move the rod along the longitudinal axis.

[0054]The rod may be made of a length of coiled tubing as is typically used in the industry.

[0055]A “subsea stroking tool” refers to a tool configured to stroke within a subsea environment. The subsea stroking tool could also be used in other environments nonetheless.

[0056]A “hydraulic piston assembly” refers to an assembly comprising at least a hydraulic piston. A hydraulic piston assembly may comprise multiple pistons and other elements.

[0057]The terms “proximal” and “distal” are used herein as relative positions along the longitudinal axis. “Distal” means closer to the extremity of the tool which is configured to interact with another object, for example to be inserted into a tubing hanger and to manipulate an object such as a plug, while “proximal” means closer to the other, opposite extremity of the tool along the longitudinal axis. When a part is moved “distally”, this means that it moves along the longitudinal axis in the proximal-to-distal direction, and when a part is moved “proximally”, this means that it moves along the longitudinal axis in the distal-to-proximal direction

[0058]The rod may have a retracted position (most proximal position), an extended position (most distal position), and an intermediate position between the retracted position and the extended position. The set of rollers may be configured to move the rod between the retracted position and the intermediate position, and the hydraulic piston assembly may be configured to move the rod between the intermediate position and the extended position.

[0059]A part (i.e. a set of rollers or a hydraulic piston assembly) “configured to move the rod between two positions” means that the part can move the rod from one position to the other position but the part can also conversely move the rod from the other position to the one position.

[0060]The action of moving the rod from the retracted position to the extended position by moving first the rod from the retracted position to the intermediate position and then moving the rod from the intermediate position to the extended position is referred to as stroking.

[0061]The set of rollers is preferably configured to do most of the stroking as the distance between the retracted position and the intermediate position is preferably greater than the distance between the intermediate position and the extended position. More generally, the set of rollers is preferably configured to move the rod along a greater distance than the hydraulic piston assembly.

[0062]Preferably, taking for example one extremity of the rod as a reference, the distance between the retracted position and the intermediate position may be from 1 m to 10 m, preferably from 2 m to 8 m; and the distance between the intermediate position and the extended position may be from 0.3 m to 1 m.

[0063]The hydraulic piston assembly may be configured to move the rod between the intermediate position and the extended position. To do so, the hydraulic piston assembly needs to exert high forces. Thus, preferably, during stroking, the final stroke is performed by the hydraulic piston assembly that can provide a higher load than the set of rollers. This higher load may be required for example to unset or set a plug in a tubing hanger as will be further explained below.

[0064]The subsea stroking tool may further comprise a connecting element attached to the distal end of the rod.

[0065]The connecting element makes it possible to connect the rod to an end tool. Such end tool may itself engage with and manipulate an external object, such as a plug.

[0066]The end tool may comprise latching fingers and a spring. Specifically, the end tool can be configured to set or recover a plug in the tubing hanger of a subsea well.

[0067]A tubing hanger is a device which is set in a Christmas tree (Xmas tree or XT) or a wellhead and suspends tubing and/or casing. The tubing hanger is configured for sealing the production or injection tubing so as to cut the circulation of fluid (typically oil or gas) within the well. The tubing hanger is usually inside the Christmas tree of the well, or below said Christmas tree. The Christmas tree is an assembly of valves, casing spools, and fittings used to regulate the flow of fluids in the well. The Christmas tree can be a VXT or an HXT. The abovementioned plug is a component that can be placed inside the tubing hanger to provide a barrier during well completion or maintenance operations.

[0068]One example of a subsea stroking tool according to the invention is shown in FIGS. 2A and 2B. In this example, the housing 200 of the subsea stroking tool 100 contains the hydraulic piston assembly 203, as well as the set of rollers 202. The set of rollers 202 may be located distally relative to the hydraulic piston assembly 203. The rod 201 is partially within the housing 200 and partially outside of the housing 200. The extent to which the rod 201 protrudes out of the housing 200 depends on whether it is in the retracted, intermediate or extended position (or in any other position between these positions). The connecting element 204 at the distal end of the rod 201 comprises a fixation for fixing to an end tool (not shown). This fixation can be for example a threaded member or a threaded hole. In FIG. 2A, the rod 201 of the subsea stroking tool 100 is in the intermediate position, and in FIG. 2B it is in the retracted position. The set of rollers 202 makes it possible to transition the rod from the retracted position to the intermediate position or conversely. The rod 201 protrudes further out of the housing 200 in this transition. The extended position of the rod 201 is not shown in FIG. 2A or 2B.

[0069]The subsea stroking tool may also comprise a circulation fluid hose, which may run along the longitudinal axis of the tool, for example up to or past the distal end of the housing, for example external to the housing. The circulation fluid hose may be configured to provide circulation fluid, such as methanol, to the area of intervention of the subsea stroking tool.

Set of Rollers

[0070]The set of rollers comprises a plurality of rollers, for example 2, 3, 4, 5, 6, 7, 8, 9, or more than 10 rollers. The rollers are configured to engage with the rod so as to move the rod along the longitudinal axis (e.g. between the retracted position and the intermediate position) when they are rotated.

[0071]The rollers may be replaceable. They may be of any diameter to suit any diameter of rod used.

[0072]An example of the set of rollers is disclosed in more details by referring to FIG. 4. It may comprise two or more longitudinally aligned rollers. It may also comprise a first group of one or more rollers and a second group of one or more rollers, the two groups engaging the rod at different circumferential positions around the longitudinal axis of the rod. The set of rollers 202 may comprise circulation channels 401 configured to let fluid circulate through them. The circulation channels 401 may allow the circulation of fluid (such as methanol or sea water) to bypass the rollers.

[0073]The set of rollers 202 may further comprise a ROV rotary interface 402. The ROV rotary interface 402 is configured for a ROV to connect to actuate the set of rollers 402 so as to move the rod along the longitudinal axis.

[0074]The (optional) circulation fluid hose 307 is also visible on FIG. 4.

Hydraulic Piston Assembly

[0075]The hydraulic piston assembly may comprise a chamber within the housing. Hydraulic fluid may be fed to the chamber or withdrawn from the chamber, so as to regulate hydraulic pressure. The hydraulic piston assembly may comprise a hydraulic piston which is slidable within the chamber. When the rod is in the retracted position, the hydraulic piston may be outside of the chamber, proximal to the chamber. When the rod is in the intermediate or extended position, the hydraulic piston may be fully or partially within the chamber. The chamber may comprise two or more portions along the longitudinal axis having different (internal) cross-sectional areas. Similarly, the hydraulic piston may comprise two or more portions along the longitudinal axis having different (external) cross-sectional areas. All cross-sectional areas as defined herein are orthogonal to the longitudinal axis.

[0076]For example, the hydraulic piston may comprise at least a distal portion closest to the rod and a proximal portion farthest from the rod. The distal portion may have a smaller cross sectional area than the proximal portion. Similarly, the chamber may comprise at least a distal portion and a proximal portion, and the distal portion may have a smaller cross sectional area than the proximal portion. Preferably, the hydraulic piston may comprise an intermediate portion between the distal portion and the proximal portion. In this case, the intermediate portion may have a smaller cross sectional area than the proximal portion and a larger cross sectional area than the distal portion. Similarly, the chamber may comprise an intermediate portion between the distal portion and the proximal portion, and the intermediate portion may have a smaller cross sectional area than the proximal portion and a larger cross sectional area than the distal portion.

[0077]The hydraulic piston may comprise another part located proximally to the proximal portion, and having an even larger cross sectional area: this is the piston centraliser mentioned elsewhere. Similarly, the chamber may comprise another space located proximally to the proximal portion, and having an even larger cross sectional area.

[0078]In this case, the cross sectional area of the portions (for both the hydraulic piston and the chamber) thus preferably decreases stepwise from the proximal to distal direction.

[0079]The hydraulic piston may have a distal end and a proximal end, the distal end of the hydraulic piston being attached to the proximal end of the rod.

[0080]The hydraulic piston assembly may also comprise at least one seal fixed on the periphery of the hydraulic piston. When the hydraulic position is in the chamber, each seal on the periphery of the hydraulic piston may define two zones on either side thereof, along the longitudinal axis, within the chamber. The respective zones on either side of a seal may be fluidically isolated, so that a hydraulic pressure differential between the zones may be applied, so as to displace the hydraulic piston.

[0081]The hydraulic piston assembly may also comprise at least one hydraulic port, configured to provide hydraulic fluid to the chamber (or withdraw hydraulic fluid from the chamber). The hydraulic piston may be configured to be actuated with hydraulic pressure provided by the hydraulic fluid coming to the chamber from at least one hydraulic port. The hydraulic piston assembly may comprise a plurality of hydraulic ports at different positions along the longitudinal axis. One or more hydraulic ports may be configured to apply hydraulic pressure so as to displace the hydraulic piston distally, for example from the intermediate position to the extended position. One or more hydraulic ports may be configured to apply hydraulic pressure so as to displace the hydraulic piston proximally, for example from the extended position to the intermediate position. In some cases, a same hydraulic port can be used for displacing the hydraulic in both directions.

[0082]The hydraulic piston may comprise a blind hole extending along the longitudinal axis from the proximal end thereof.

[0083]An example of the hydraulic piston assembly is disclosed in more detail by referring to FIG. 3A/3B/3C/3D. The hydraulic piston assembly 203 of the subsea stroking tool is presented when the rod 201 is in the intermediate position in FIG. 3A/3B. The hydraulic piston assembly 203 comprises a hydraulic piston 301 configured to slide through the chamber 300. The hydraulic piston 301 may comprise a piston centraliser 306 at the proximal end thereof. Between the piston centraliser 306 and the point at which the rod 201 is attached to the hydraulic piston 301, the hydraulic piston 301 may successively comprise, in the proximal to distal direction: a proximal portion 311, an intermediate portion 312 and a distal portion 313. The (external) cross-sectional area of the hydraulic piston 301 decreases stepwise from the proximal portion 311, to the intermediate portion 312 and then the distal portion 313.

[0084]The chamber 300 may similarly comprise a proximal portion 314, an intermediate portion 315 and a distal portion 316. The (internal) cross-sectional area of the chamber 300 decreases stepwise from the proximal portion 314, to the intermediate portion 315 and then the distal portion 316.

[0085]In the intermediate position as illustrated on FIG. 3A/3B, the proximal portion 311 of the hydraulic piston 301 may substantially or fully lie outside of the chamber 300, the intermediate portion 312 of the hydraulic piston 301 may substantially or fully lie in the proximal portion 314 of the chamber 300, and the distal portion 313 of the hydraulic piston 301 may substantially or fully lie in the intermediate portion 315 of the chamber 300.

[0086]In the extended position, the proximal portion 311 of the hydraulic piston 301 may substantially or fully lie in the proximal portion 314 of the chamber 300, the intermediate portion 312 of the hydraulic piston 301 may substantially or fully lie in the intermediate portion 315 of the chamber 300, and the distal portion 313 of the hydraulic piston 301 may substantially or fully lie in the distal portion 316 of the chamber 300.

[0087]In the illustrated example, a first seal 308 may be provided on the periphery of the proximal portion 311 of the hydraulic piston 301, preferably at or close to the distal end of this portion; a second seal 309 may be provided on the periphery of the intermediate portion 312 of the hydraulic piston 301, preferably at or close to the distal end of this portion; and a third seal 310 may be provided on the periphery of the distal portion 313 of the hydraulic piston 301, preferably at or close to the distal end of this portion.

[0088]Each seal preferably engages with the chamber 300 so as to fluidically isolate respective zones on either side of the seal and thus apply a hydraulic pressure differential across the seal (at least when the rod is in the intermediate position, the extended position, or any position in-between).

[0089]In the illustrated example, a first hydraulic port 305 may be provided proximal relative to the proximal portion 314 of the chamber 300; a second hydraulic port 304 may be provided in the proximal portion 314 of the chamber 300 (preferably close to the distal end thereof); a third hydraulic port 303 may be provided in the intermediate portion 315 of the chamber 300 (preferably close to the distal end thereof); and a fourth hydraulic port 302 may be provided in the distal portion 316 of the chamber 300 (preferably close to the distal end thereof).

[0090]In order to move the hydraulic piston 301 distally, starting from the intermediate position illustrated in FIG. 3A/3B, it is possible to feed hydraulic fluid via the first hydraulic port 305 and to withdraw hydraulic fluid via one or more of the other hydraulic ports. Alternatively, it is possible to feed hydraulic fluid via the second hydraulic port 304 and to withdraw hydraulic fluid via the third hydraulic port 303 and/or the fourth hydraulic port 302. The second hydraulic port 304 can thus act as a backup to the first hydraulic port 305. It is also possible to feed hydraulic fluid via both the first hydraulic port 305 and second hydraulic port 304 and to withdraw hydraulic fluid via the third hydraulic port 303 and/or the fourth hydraulic port 302.

[0091]In order to move the hydraulic piston 301 proximally, starting from the extended position to transition to the intermediate position illustrated in FIG. 3A/3B, it is possible to feed hydraulic fluid via the third hydraulic port 303 and to withdraw hydraulic fluid via the second hydraulic port 304 and/or first hydraulic port 305. Alternatively, it is possible to feed hydraulic fluid via the second hydraulic port 304 and to withdraw hydraulic fluid via the first hydraulic port 305. The second hydraulic port 304 can thus act as a backup to the third hydraulic port 303. It is also possible to feed hydraulic fluid via both the third hydraulic port 303 and second hydraulic port 304 and to withdraw hydraulic fluid via the first hydraulic port 305.

[0092]In each case, the hydraulic piston 301 may be caused to move along the longitudinal axis by applying a hydraulic pressure differential across the first seal 308 and/or the second seal 309.

[0093]The third seal 310 can provide a pump out area if hydraulic pressure is applied distally to it. The third seal 310 also provides a sealing point for the second seal 309 to push proximally, when hydraulic fluid is injected via the third hydraulic port 303.

[0094]The piston centraliser 306 may comprise a blind hole to collect any debris and avoid interference with the operation of the hydraulic piston 301. The circulation fluid hose 307 already mentioned above is also visible on FIG. 3A/3C/3D.

[0095]FIG. 6A/6B also more schematically show the hydraulic piston 301 within the chamber 300, in the intermediate position (FIG. 6A) and in the extended position (FIG. 6B). In these two drawings, part of the proximal portion 311 of the hydraulic piston as well as the piston centraliser are not depicted.

[0096]Another example of hydraulic piston assembly is disclosed in more detail by referring to FIG. 7A/7B/7C/7D.

[0097]Just like in the case of FIG. 3A/3B/3C/3D, the subsea stroking tool comprises a housing 200, a hydraulic piston assembly 203, a rod 201 and a set of rollers 202 engaged with the rod 201; the hydraulic piston assembly 203 comprises a hydraulic piston 301 configured to slide through a wear sleeve 300′. However, contrary to the case of the chamber in FIG. 3A/3B/3C/3D, the wear sleeve 300′ does not comprise various portions of different internal cross-sections. Instead, the wear sleeve 300′ may have a relatively constant internal cross-section along the longitudinal axis. The rod 201 may slide within the hydraulic piston 301 (it is therefore not permanently attached to the hydraulic piston 301).

[0098]The rod 201 may have a proximal shoulder 701 at the proximal end, and the hydraulic piston 301 may comprise a plurality of load segments 702, such as for example 2 to 16 load segments, preferably 4 to 10 load segments, for example 6 load segments. The load segments 702 may be circumferentially arranged around the longitudinal axis, at one position along the longitudinal axis. The load segments 702 may be radially movable between a locked position and an unlocked position. In the unlocked position, the load segments 702 are radially collapsed outwards, whereas in the locked position, they radially extend inwards, within the inner space through which the rod 201 is able to slide. The load segments 702 are configured to cooperate with the shoulder 701 of the rod 201 when in the locked position.

[0099]FIG. 7A shows the rod 201 in the retracted position. In this position, the shoulder 701 is proximal to the load segments 702. The hydraulic piston 301 lies within the wear sleeve 300′.

[0100]FIG. 7B shows the rod 201 in the intermediate position. The hydraulic piston 301 is still in the same position as in FIG. 7A. The shoulder 701 is positioned slightly distally relative to the load segments 702. The detail in FIG. 7B shows the load segments 702 in the unlocked position. As described elsewhere, the rod 201 transitions from the retracted position to the intermediate position owing to the set of rollers 202.

[0101]FIG. 7C and the detail thereof show the hydraulic piston 301 with the load segments in the locked position, the hydraulic piston 301 having moved slightly distally, so that it engages with the shoulder 701 of the rod 201 via the load segments 701. The tool is then ready to transition the rod 201 from the intermediate position to the extended position, by moving the hydraulic piston 301 further distally and accordingly pushing the rod 201.

[0102]FIG. 7D shows the rod 201 in the extended position.

[0103]In the illustrated example, a first (proximal) hydraulic port 703 and a second (distal) hydraulic port 704 may be provided in the wear sleeve 300′. The hydraulic piston 301 may have a seal on the periphery thereof, located between the first hydraulic port 703 and the second hydraulic port 704, and engaging with the inner wall of the wear sleeve 300′ so as to fluidically isolate respective zones on either side of the seal within the wear sleeve 300′ and thus apply a hydraulic pressure differential across the seal.

[0104]In order to move the hydraulic piston 301 distally, starting from the intermediate position illustrated in FIG. 7B/7C, it is possible to feed hydraulic fluid via the first hydraulic port 703 and/or to withdraw hydraulic fluid via the second hydraulic port 704.

[0105]In order to move the hydraulic piston 301 proximally, starting from the extended position illustrated in FIG. 7D, it is possible to feed hydraulic fluid via the second hydraulic port 704 and/or to withdraw hydraulic fluid via the first hydraulic port 703.

[0106]In each case, the hydraulic piston 301 may be caused to move along the longitudinal axis by applying a hydraulic pressure differential in the wear sleeve 300′ across the seal of the hydraulic piston 301.

[0107]The load segments 702 have to be in the unlocked position when the rod 201 moves proximally to the retracted position so that the rod 201 may slide proximally within the hydraulic piston 301.

[0108]In all of the above embodiments, the hydraulic piston assembly may be configured to be actuated by a ROV.

[0109]In this case, the hydraulic piston assembly preferably further comprises a ROV interface. The ROV interface may enable connection of the ROV to the hydraulic piston assembly. The ROV may comprise a hydraulic fluid circuit, which can be fluidically connected to one or more of the hydraulic ports of the hydraulic piston assembly. As a result, the ROV may supply hydraulic fluid to the chamber and/or withdraw hydraulic fluid from the chamber via one or more of these hydraulic ports, as described above.

[0110]The ROV interface may comprise one or more hot stab receptacles, which can each include one or more ports, for example 1, 2 or 4 ports. Once the ROV is connected to the ROV interface, hydraulic fluid may be applied to each port individually so as to operate the tool in the desired sequence.

[0111]The ROV may also actuate the load segments, if present, from the unlocked position to the locked position and vice versa.

Integration of the Subsea Stroking Tool in a Well Control Package

[0112]The subsea stroking tool may be integrated in a well control package to be placed on top of a subsea tree. Referring to FIG. 1A and FIG. 1B, the subsea stroking tool 100 is integrated in a well control package (WCP) 104 placed on top of a subsea tree 103. A connector 102 connects the subsea stroking tool 100 inside the well control package 104 placed on top of the subsea Xmas tree 103 via a XTAC (Xmas Tree Adaptor Connector) 105.

[0113]An example of the well control package is disclosed in more detailed by referring to FIG. 5. The subsea stroking tool 100 is integrated in the well control package 104 via the connector 102. The well control package 104 is placed on top of the subsea Xmas tree 103. The subsea stroking tool is configured to extend in the wellhead 503.

Method of Operating

[0114]Another object of the present invention is a method of operating the subsea stroking tool. The method comprises a step of moving the rod along the longitudinal axis by actuating the set of rollers and a step of moving the rod along the longitudinal axis by actuating the hydraulic piston assembly. The method may comprise first the step of moving the rod along the longitudinal axis by actuating the set of rollers, and then, the step of moving the rod along the longitudinal axis by actuating the hydraulic piston assembly, or first the step of moving the rod along the longitudinal axis by actuating the hydraulic piston assembly, and then, the step of moving the rod along the longitudinal axis by actuating the set of rollers.

[0115]The method may comprise a step of moving the rod distally along the longitudinal axis by actuating the set of rollers, followed by a step of moving the rod distally along the longitudinal axis by actuating the hydraulic piston assembly. In such a case, the rod of the subsea stroking tool may extend outside of the housing of the subsea stroking tool as the rod reaches its extended position. In such a case, the method may be used in a process of connecting an object. The method may also be used in a process of setting an object in another device. For example, the method may be used to reach the inside of a tubing hanger on a wellhead. The method may therefore be used for setting a plug previously connected to the rod (via the end tool) inside the tubing hanger of a subsea tree.

[0116]The method may comprise a step of moving the rod proximally along the longitudinal axis by actuating the hydraulic piston assembly followed by a step of moving the rod proximally along the longitudinal axis by actuating the set of rollers. In such a case, the rod of the subsea stroking tool may retract inside the housing of the subsea stroking tool as the rod reaches its retracted position. In such a case, the method may be used in a process of connecting an object. The method may also be used in a process of recovering an object in another device. For example, the method may be used to recover an object, such as a plug, in a tubing hanger on a wellhead.

[0117]The method may be used for setting a plug in a tubing hanger of a wellhead. In this case, the method may firstly comprise connecting the plug to the end tool attached to the distal end of the rod. The plug may be fixedly attached to the end tool so that it moves longitudinally together with the rod. The method may further comprise placing the plug in a desired position in the tubing hanger by moving the rod distally along the longitudinal axis by actuating the set of rollers (for example from the retracted position to the intermediate position), followed by moving the rod distally along the longitudinal axis by actuating the hydraulic piston assembly (for example from the intermediate position to the extended position). Finally, the method may comprise releasing the plug from the end tool and withdrawing the subsea stroking tool by moving the rod proximally along the longitudinal axis by actuating the hydraulic piston assembly (for example from the extended position to the intermediate position) followed by moving the rod proximally along the longitudinal axis by actuating the set of rollers (for example from the intermediate position to the retracted position). In order for the end tool to releasably latch on the plug, the end tool may comprise latching fingers and a spring, so that, depending on the force exerted longitudinally by said end tool when it is engaged with the plug, the latching fingers may expand or retract, thus ensuring either that the end tool latches on the plug or is free to be separated from the plug.

[0118]The method may be used for recovering a plug in a tubing hanger of a wellhead. In this case, the method may firstly comprise placing the rod in a desired position in the tubing hanger by moving the rod distally along the longitudinal axis by actuating the set of rollers (for example from the retracted position to the intermediate position), followed by moving the rod distally along the longitudinal axis by actuating the hydraulic piston assembly (for example from the intermediate position to the extended position). The method may further comprise connecting the end tool attached to the distal end of the rod to the plug (for example by exerting an appropriate force in the longitudinal direction). The method may further comprise withdrawing the subsea stroking tool having the plug connected thereto, by moving the rod proximally along the longitudinal axis by actuating the hydraulic piston assembly (for example from the extended position to the intermediate position) followed by moving the rod proximally along the longitudinal axis by actuating the set of rollers (for example from the intermediate position to the retracted position).

[0119]FIG. 1A shows a subsea stroking tool 100 wherein the rod of the subsea stroking tool 100 is in the extended position. The rod of the subsea stroking tool 100 is connected to a slickline plug 101 inside the tubing hanger of a subsea Xmas tree 103. In this case, the rod of the subsea stroking tool 100 may either release the slickline plug 101 inside the tubing hanger of the subsea Xmas tree 103 or either further recover the slickline plug 101 from the tubing hanger of the subsea Xmas tree 103.

[0120]FIG. 1B discloses the subsea stroking tool 100 wherein the rod of the subsea stroking tool 100 is in the retracted position. The slickline plug 101 has been recovered from the subsea Xmas tree 103 as it is still connected to the rod of the subsea stroking tool 100.

[0121]Each step of moving the rod may be carried out by actuating the subsea stroking tool with a ROV. The ROV may successively or alternately connect to the ROV interface of the set of rollers and to the ROV interface of the hydraulic piston assembly, so as to actuate the set of rollers and the hydraulic piston assembly respectively. As shown on FIG. 5, the ROV may in particular comprise a hydraulic skid 504 which may be connected to one or more hydraulic ports of the hydraulic piston assembly via one or more hydraulic hoses 501. The hydraulic skid 504 may include a pump and fluid to actuate the pistons via the hot stab receptacles. The ROV may also comprise a torque tool to turn the roller drive. By alternating between the torque tool and hot stabs, the correct sequence of operation can be achieved.

[0122]The method may further comprise injecting fluid (for example via the circulation fluid hose described above) before actuating the rod, especially around the stroking tool and the tree. For example, this step may be used to clean any material which may be inside the tubing hanger such as mud or debris as well as to displace water. The injection of fluid may avoid formation of hydrates and thus facilitate the recovery or the installation of a plug.

[0123]In other examples, a method of operating the subsea stroking tool may comprise a step of moving the rod along the longitudinal axis by actuating the set of rollers and may not comprise any step of moving the rod along the longitudinal axis by actuating the hydraulic piston assembly. This can be useful in situations where a high load is not required during stroking. Such a method may be for example a method for milling, for hydrate removal, or for bridge plug setting below the tubing hanger.