SUBSEA CONNECTION SYSTEM FOR CONNECTING A HOT STAB OF A FLOWLINE TO A SUBSEA STRUCTURE

Abstract

A subsea connection system has a subsea structure with a flow channel therein and a port at one end of the flow channel, a stab having a flowline connected thereto, and a frame affixed to the stab. The stab is adapted to engage the port of the subsea structure so as to allow a fluid to flow from the flowline into the flow channel. The frame has a hook portion that is engageable with a tool hanger of the subsea structure so as to support the stab in alignment with the port. The frame is pivotable about the tool hanger so as to move the stab toward the port. An actuator is cooperative with the stab so as to move the stab between a retracted position and an extended position.

Claims

1. A subsea connection system comprising: a subsea structure having a flow channel therein, said flow channel having a port adjacent one end thereof, said subsea structure having a tool hanger positioned on an outer surface thereof adjacent said port, said tool hanger extending longitudinally outwardly beyond an end of said port; a stab having a flowline connected thereto, said stab adapted to engage said port of said subsea structure so as to allow a fluid to flow from said flowline into said flow channel of said subsea structure; a frame affixed to said stab, said frame being a fixed structure, said frame having a fixed hook portion that is engageable with said tool hanger of said subsea structure so as to support said stab in horizontal alignment with said port of said flow channel, said fixed hook portion positioned above said frame and positioned longitudinally outwardly beyond an end of said frame, said fixed hook portion being pivotable around said tool hanger so as to move said stab into horizontal alignment with said port; and an actuator cooperative with said stab so as to move said stab interior of said frame between a retracted position and an extended position, the extended position connecting said stab to said port.

2. (canceled)

3. The subsea connection system of claim 1, said actuator being a hydraulic actuator.

4. The subsea connection system of claim 3, said hydraulic actuator having a pair of ports opening outwardly thereof, one of said pair of ports of said hydraulic actuator adapted to allow a remotely-operated vehicle to move said stab from the retracted position to the extended position, the other of said pair of ports of said hydraulic actuator adapted to allow the remotely-operated vehicle to move said stab from the extended position to the retracted position.

5. The subsea connection system of claim 1, further comprising: a lock member affixed to said frame, said lock member engageable with said subsea structure so as to fix a position of said frame with respect to said port of said subsea structure.

6. The subsea connection system of claim 5, said lock member having a receptacle on one of said frame and said subsea structure and a pin on the other of said frame and said subsea structure, said pin being rotatable so as to engage said receptacle.

7. The subsea connection system of claim 1, said flowline having an inner diameter greater than two inches.

8. The subsea connection system of claim 7, said inner diameter of said flowline being four inches.

9. The subsea connection system of claim 1, said subsea structure being a relief well injection spool.

10. The subsea connection system of claim 1, further comprising: a line affixed to said frame and extending upwardly therefrom, said line being payable so as to cause said frame to pivot about said tool hanger of said subsea structure.

11. A method of connecting a stab to a port of a flow channel of a subsea structure, the stab being received interior of a frame, the frame having a fixed hook positioned longitudinally outwardly beyond an end of said frame, the frame being a fixed structure, the stab having a flowline connected thereto, the subsea structure having a tool hanger extending longitudinally outwardly beyond the port, the method comprising: lowering the frame and the stab toward the subsea structure; moving the frame so that the fixed hook engages the tool hanger; pivoting the fixed hook around the tool hanger such that the stab is in horizontal alignment with and in proximity to the port of the subsea structure; and actuating the stab within the frame so that the stab moves horizontally from a retracted position to an extended position relative to the fixed structure of the frame so as to establish a fluid connection between the flowline and the flow channel.

12. (canceled)

13. The method of claim 11, further comprising: locking the frame to the subsea structure after the step of pivoting.

14. The method of claim 13, the step of locking comprising: engaging a locking pin on the frame with a receptacle on the subsea structure.

15. The method of claim 11, the step of actuating comprising: connecting a remotely-operated vehicle to a hydraulic actuator, the hydraulic actuator being affixed to the frame and cooperative with the stab; and flowing hydraulic fluid from the remotely-operated vehicle to the hydraulic actuator so as to move the stab from the retracted position to the extended position.

16. The method of claim 11, the frame being connected to a line, the step of lowering comprising: paying out the line from a surface location until the frame and the stab are in proximity to the subsea structure.

17. The method of claim 16, the step of pivoting comprising: further paying out the line from the surface location until the line becomes slack.

18. The method of claim 11, further comprising: connecting the flowline to the stab so as to establish a fluid connection between the flowline and the stab, the flowline having an inner diameter greater than two inches.

19. The method of claim 11, further comprising: flowing a fluid through the flowline and through the stab into the flow channel of the subsea structure.

20. The method of claim 13, further comprising: retracting the stab within the frame so as to separate the stab from the port of the subsea structure; unlocking the frame from the subsea structure; and raising the frame and the stab toward a surface location.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0038] FIG. 1 is a side elevational view of the system of the present invention with the frame and hot stab in proximity to the subsea structure.

[0039] FIG. 2 is a perspective view of the frame and hot stab in proximity to the subsea structure.

[0040] FIG. 3 is a side elevational view showing the placement of the hook portion of the frame with the tool hanger of the subsea structure.

[0041] FIG. 4 shows is a side elevational view of an initial step of pivoting the frame with respect to the subsea structure.

[0042] FIG. 5 is a side elevational view of the system of the present invention in which the frame and hot stab have been rotated to a position in which the hot stab is in alignment with the port and flow channel of the subsea structure.

[0043] FIG. 6 is a side elevational view of the system of the present invention showing the locking pin in the unlocked position.

[0044] FIG. 7 is a close-up perspective view of the locking pin used to lock the frame to the subsea structure.

[0045] FIG. 8 is a side elevational view of the system of the present invention in which the hot stab is in a retracted position.

[0046] FIG. 9 is a side elevational view of the system of the present invention in which the hot stab is engaged with the port of the flow channel of the subsea structure.

[0047] FIG. 10 is a side elevational view showing the step of separating the hot stab from the port of the subsea structure.

DETAILED DESCRIPTION OF THE INVENTION

[0048] Referring to FIG. 1, there is shown the subsea connection system 10 in accordance with teachings of the present invention. The subsea connection system 10 has a subsea structure 12, a stab 14, a frame 16, and a flowline 18 connected to the stab 14. The subsea structure 10 has a flow channel 20 therein. A port 22 is located at one end of the flow channel 20. The subsea structure 12 also has a tool hanger 24 positioned at an outer surface thereof adjacent to the port 22. The stab 14 is adapted to engage the port 22 of the subsea structure 12 so as to allow a fluid to flow from the flowline 18 into the flow channel 20 of the subsea structure 12. The frame 16 is affixed to the stab. The frame 16 has a hook portion 26 that is engageable with the tool hanger 24 of the subsea structure 12 so as to support the stab 14 in alignment with the port 22 of the flow channel 20. As will be described hereinafter, the frame 16 will be pivotable about the tool hanger 24 so as to move the stab 14 toward the port 22.

[0049] The system 10 of the present invention is adaptable to a wide variety of subsea structures. In FIG. 1, the subsea structure that is utilized with the system 10 of the present invention is a relief well injection spool. As was described hereinbefore, the relief well injection spool is intended to be attached to a wellhead of a relief well so as to allow for high-volume and high-pressure fluids to flow through the relief well into the bore of a well that is blowing. The relief well injection spool 10 includes a central bore 28 that extends vertically through the relief well injection spool. A wellhead connector 30 is adapted for flanged connection to the relief well wellhead. The flow channel 20 extends horizontally through the relief well injection spool of the subsea structure 12 so as to open to the bore 28. Various valves are utilized on the subsea structure 12 so as to control the flow into the bore 28. The subsea structure 12 has a mandrel 32 extending upwardly there from. Mandrel 32 can be adapted to be connected to the bottom of a blowout preventer.

[0050] FIG. 1 illustrates an initial step in the method of the present invention. In particular, there is a downline 34 that extends from a surface location, such as a kill vessel. Tool rigging 36 is connected to the downline 34 and is joined to a shackle 38 on the frame 16. The hot stab 14 is received within the interior of the frame 16 and is affixed thereto. The hot stab 14 will have a connector 40 at an end thereof. Connector 40 allows the hot stab 14 to be connected to the flowline 18. The downline 34 is payed out from the surface location so as to be lowered such that the frame 16 and the stab 14 is in proximity to the subsea structure 12. It can be seen that the hook portion 26 is separate from the tool hanger 24 on the subsea structure 12.

[0051] As described herein, the flowline 18 will be a high-volume high-pressure flowline. In particular, so as to allow the relief well injection spool to carry out the necessary delivery of fluids so as to kill the well, the flowline 18 will have an inner diameter of greater than two inches. Preferably, the flowline 18 will have a four inch inner diameter. As such, the stab 14 will be a four inch stab. This stab will have a very large weight. As such, the frame 16 and the stab 14 would be too heavy to be carried and manipulated by a a remotely-operated vehicle. In FIG. 1, it can be seen that the entire weight of the frame 16, the stab 14 and the flowline 18 is supported by the downline 34 and the tool rigging 36 from the surface location.

[0052] FIG. 2 is a perspective view showing that the initial step of the installation of the frame 16 to the tool hanger 24. The tool hanger 24 is in the nature of a rod or bar that extends generally in a horizontal plane above the port 22 of the flow channel. It also extends slightly outwardly beyond the end of the port 22. As such, the tool hanger 24 will be in an appropriate location so as to receive the hook portion 26 of the frame 16. The tool rigging 36 includes first and second cables that are connected to a clevis 42. Clevis 42 can then, in turn, be connected to the downline 34. The flowline 18 extends outwardly from the opposite end of the frame 16 and upwardly toward a surface location or other location having a supply of fluid.

[0053] FIG. 3 shows that the frame 16 is still supported by tool rigging 36. An ROV is used so as to move the frame 16 so that the hook portion 26 resides over the tool hanger 24. The hook portion 26 has a semicircular slot therein which has radius suitable for accommodating the diameter of the rod or bar of the tool hanger 24. In this position, the stab 14 is still separate from the port 22 of the subsea structure 12. The frame 16 will extend slightly upwardly at an angle away from the subsea structure 12.

[0054] FIG. 4 shows that the hook portion 26 has been lowered by the action of the downline 34 and the tool rigging 36 so as to engage with the tool hanger 24. The frame 16 still remains at an upwardly-turned angle away from the port 22 of the subsea structure 12. The stab 14 is in a retracted position within the frame 16 during this operation. As such, the end of the stab 14 will not interfere with the ability to properly installed the hook portion 26 on the tool hanger 24. Throughout the operations shown in FIGS. 3 and 4, virtually the entire weight of the frame 16, the stab 14 and the flowline 18 is supported by the downline 34 and the tool rigging 16.

[0055] In FIG. 5, the hook portion 26 remains engaged with the tool hanger 24. The tool rigging 36 and the downline 34 are lowered from the surface location by paying out the downline 34. As such, the frame 16 will pivot with respect to the tool hanger 24 so as to be aligned with the flow channel 20 of the subsea structure 12. The flowline 18 will extend outwardly of the frame 16 and the stab 14 in general alignment with the flow channel 20.

[0056] FIG. 5 shows that there is a locking member 50 that is provided on the forward end of the frame 16 away from the flowline 18. The locking member 50 is in the nature of a locking pin that is rotatable or pivotable relative to the frame 16. The locking member 50 is aligned with a receptacle 52 on the subsea structure 12. When the hook portion 26 is pivoted relative to the tool hanger 24 and the stab 14 is in alignment with the port 22 of the flow channel 18, the locking member 50 should be aligned with the receptacle 52.

[0057] FIG. 6 shows that the locking member 50 has been manipulated so as to engage with the receptacle 52 so as to lock the frame 16 in relation to the subsea structure 12. It is important to lock the frame 16 to the subsea structure 12 prior to actuating the stab 14. If it were not locked, then the forces imparted by the stab 14 to the port of the subsea structure 12 would cause the frame 16 and the hot stab 14 to pivot away from the subsea structure 12 and, as such, would establish an improper connection. The locking member 50 can be easily manipulated by a remotely-operated vehicle. In one embodiment, it is only necessary to rotate the locking pin of the locking member so that it is received within the receptacle 52. This arrangement establishes a strong and fixed connection between the frame 16 and the subsea structure 12.

[0058] FIG. 7 shows a detailed view of the locking member 50 and the receptacle 52. There is an arm 60 that extends outwardly of the locking member 50. Arm 60 can be grasped by the remotely-operated vehicle and rotated so that the locking member 50 engages the receptacle 52. To separate the locking member 50 from the receptacle 52, it is only necessary for the remotely-operated vehicle to rotate the arm 60 in an opposite direction. Once again, the remotely-operated vehicle carries none of the weight of the assembly.

[0059] FIG. 8 shows that the stab 14 is in a retracted position within the frame 16. Importantly, there is an actuator 62 that is provided at an end of the frame 60. Actuator 62 is cooperative with the stab 14 so as to move the stab 14 between a retracted position (as shown in FIG. 8) and an extended position (as shown in FIG. 9). Actuator 62 can be a mechanical or hydraulic actuator. In the preferred embodiment of the present invention, the actuator 62 is a hydraulic actuator. As such, an ROV can connect with the actuator 62 so as to inject pressurized hydraulic fluid into the actuator 62. This will cause the stab 14 to move from the retracted position to the extended position. The actuator 62 is a dual port actuator. As such, when hydraulic fluid is injected into one of the ports of the actuator 62, it will move the stab 14 from the retracted position to the extended position. When the hydraulic fluid from the ROV is introduced into the other port of the actuator 62, it will move the stab 14 from the extended position to the retracted position.

[0060] FIG. 9 shows that the actuator 62 has been actuated so as to move the stab 14 to the extended position. In this extended position, the stab 14 will engage with the port of the subsea structure 12 so as to establish a fluid connection between the flowline 18 and the flow channel 20 of the subsea structure 12. The actuator 62 will maintain the stab 14 in this extended position so as to withstand any separation forces that might occur. The flowline 18 can then deliver high-volume and high-pressure fluids into the subsea structure 12.

[0061] At this stage, the subsea structure 12 can be used for its intended purpose. To the extent that the subsea structure 12 is a relief well injection spool, the flowline 18 can deliver the high pressure high-volume fluids through the relief well injection spool, through the relief well, and into the main bore of the flowing well. When the flowing well has been capped, the stab 14 can be released, the frame 16 can be removed and the entire assembly can be returned to the surface by the downline 34 and the tool rigging 36.

[0062] FIG. 10 shows the initial step of the separation procedure. In FIG. 10, the actuator 62 has been actuated so as to separate the stab 14 from its engagement with the port 22 of the flow channel 20. The tool rigging 36 and the downline 34 can be lifted upwardly so as to return the frame 16, the stab 14 and the flowline 18 to a surface location for reuse elsewhere.

[0063] It should be noted that in the installation of the system of the present invention, the connection between the hot stab and the subsea structure is accomplished through the use of gravity. Gravity will encourage they frame and the stab to rotate downwardly with respect to the tool hanger. The downline 34 and the tool rigging 36 will, at all times, support the weight of the assembly. The remotely-operated vehicle is only utilized for the purposes of fine manipulation and for actuation. The remotely-operated vehicle simply moves the supported weight of the assembly to its proper position at the tool hanger. The downline will continue to be played out until the downline becomes slack. Once the downline become slack, it is assured that the frame 16 has pivoted through its entire range of motion so as to be in alignment with the flow channel 20 of the subsea structure 12.

[0064] It should be noted that the flowlines having an inner diameter of two inches or less can be manipulated by a conventional remotely-operated vehicle. Additionally, the weight of such a hot stab on such small flowlines can be supported by the remotely-operated vehicle. As such, with conventional flowlines, it would not be necessary to use the frame assembly, the tool hanger, and actuators of the present invention. Since the present invention deals with flowlines having a diameter of greater than two inches and, in particular, an inner diameter of four inches, the present invention is able to establish a quick and easy deployment of such large flowlines in a secure and safe manner. As such, in the event of a well blowout, the relief well injection spool, along with the high volume, high-pressure flowline can be installed out with maximum efficiency.

[0065] The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction can be made within the scope of the appended claims without departing from the true spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.