Abstract
A process for installing or removing a subsea structure in a non-vertical manner at a well includes securing a plurality of barges together in a linear formation in which one of the plurality of barges has a downline extending therefrom, connecting an end of the barges to a primary vessel, moving the primary vessel such that one of the barges is positioned over a target at or adjacent to the well, connecting a plurality of secondary vessels by plurality of mooring lines to an opposite end of the barges, tensioning the mooring line so as to fix the opposite end of the barges, positioning a deployment vessel away from the barges, deploying an ROV, manipulating the ROV so as to connect the subsea structure to the downline, and moving the downline and the subsea structure toward or away from the well.
Claims
1. A process for installing or removing a subsea structure in a non-vertical manner at a well, the process comprising: securing a plurality of barges together in a linear formation in which one of the plurality of barges has a downline extending therefrom; connecting one end of the plurality of barges to a primary vessel; moving the primary vessel such that at least one of plurality of barges is positioned over a target at or adjacent to the well; connecting a plurality of secondary vessels by a plurality of mooring lines adjacent an opposite end of the plurality of barges; tensioning the plurality of mooring lines so as to fix a position of the opposite end of the plurality of barges; positioning a deployment vessel away from the plurality of barges; deploying an remotely-operated vehicle (ROV) from the deployment vessel; deploying the subsea structure from the deployment vessel; manipulating the ROV so as to connect the subsea structure to the downline; and moving the downline and the subsea structure toward or away from the well.
2. The process of claim 1, the well being a blowing well, the blowing well forming a plume at a water surface, the step of moving the primary vessel comprising: moving the primary vessel such that at least one of the plurality of barges is positioned within the plume.
3. The process of claim 2, the target being a wellhead of the blowing well, a blowout preventer at the blowing well, or a lower marine riser package at the blowing well.
4. The process of claim 3, further comprising: lowering the subsea structure from the deployment vessel toward the target; and moving the subsea structure with the ROV toward the downline.
5. The process of claim 4, the step of moving the downline comprising: lowering the downline and the subsea structure toward the target; and affixing the subsea structure to the wellhead or to the blowout preventer at the wellhead.
6. The process of claim 1, the subsea structure being positioned adjacent to the well, the process comprising: deploying the ROV such that the ROV moves downwardly toward the subsea structure; affixing the downline to the subsea structure with the ROV; and raising the subsea structure by paying in the downline from the plurality of barges.
7. The process claim 1, the step of tensioning comprising: moving the plurality of secondary vessels so as to triangulate the opposite end of the plurality of barges within the primary vessel and the plurality of secondary vessels.
8. The process of claim 7, the step of moving the plurality of secondary vessels comprises arranging the secondary vessels at an approximately 120 angle relative to the linear formation of the plurality of barges.
9. The process of claim 5, the subsea structure being a capping stack, the step of affixing the subsea structure comprising: affixing the capping stack to the blowout preventer.
10. The process of claim 2, the primary vessel and the plurality of secondary vessels residing outside the plume throughout the process.
11. The process of claim 1, the step of moving the primary vessel comprising: moving the primary vessel and the plurality of barges in a direction that is downwind.
12. The process of claim 1, each of the plurality of secondary vessels having a winch thereon, the step of tensioning comprising: actuating the winch so as to pay in the mooring lines such that the mooring lines of the plurality of secondary vessels are tensioned so that the opposite end of the plurality of barges is fixed in position over the well.
13. The process of claim 1, the deployment vessel being one of the primary vessel and the plurality of secondary vessels.
14. The process of claim 1, the step of moving the primary vessel comprising: moving the primary vessel and the plurality of secondary vessels such that the opposite end of the plurality of barges is located directly above the well.
15. The process of claim 4, further comprising: moving the subsea structure laterally into the plume with the ROV prior to the step of lowering.
16. The process of claim 15, further comprising: positioning the subsea structure above a mandrel of the blowout preventer; lowering the subsea structure on the blowout preventer; and locking the subsea structure on the mandrel of the blowout preventer.
17. The process of claim 16, further comprising: releasing the downline from the subsea structure after the subsea structure is affixed to the blowout preventer or the wellhead.
18. A process for installing a subsea structure in a non-vertical manner at a blowing well, the blowing well forming a plume of hydrocarbons at a water surface, the process comprising: securing a plurality of barges together in a linear formation in which one of the plurality of barges has a downline extending therefrom; connecting one end of the plurality of barges to a primary vessel; moving the primary vessel toward the plume such that at least one of the plurality of barges is positioned within the plume; connecting a plurality of secondary vessels by a plurality of mooring lines adjacent an opposite end of the plurality of barges; tensioning the plurality of mooring lines so as to fix a position of the opposite end of the plurality of barges generally above the wellhead of the blowing well; positioning a deployment vessel away from the periphery of the plume; deploying a remotely-operated vehicle (ROV) from the deployment vessel: lowering the subsea structure from the deployment vessel downwardly toward a seabed; moving the subsea structure with the ROV toward the downline from the plurality of barges; connecting the subsea structure to the downline; moving the downline and the subsea structure toward the blowing well; and affixing the subsea structure to the wellhead or to a blowout preventer at the wellhead.
19. The process of claim 18, the step of tensioning comprising: moving the plurality of secondary vessels so as to generally triangulate the opposite end of the plurality of barges within the primary vessel and the plurality of secondary vessels.
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
(1) FIG. 1 is a diagrammatic illustration of the system of the present invention.
(2) FIG. 2 is a plan view showing the orientation of the various vessels in a final deploying position associated with the system of the present invention.
(3) FIG. 3 is a plan view showing an initial manner of deploying the system of the present invention.
(4) FIG. 4 is a side elevational view showing an initial step in the process of the present invention.
(5) FIG. 5 is a side elevational view showing the following deploying step in the process of the present invention.
(6) FIG. 6 is a side elevational view showing a further deploying step in the process of the present invention.
(7) FIG. 7 of the site elevation showing a further deploying step in the process of the present invention.
(8) FIG. 8 shows a side elevational view showing the final deploying step of the process of the present invention.
(9) FIG. 9 is a side elevational view showing the process of the present invention involving a passive heave compensator on the downline from the plurality of barges.
(10) FIG. 10 is an isolated side elevational view of the passive heave compensator of the present invention.
(11) FIG. 11 is a diagrammatic illustration of the internal components of the passive heave compensator of the present invention.
(12) FIG. 12 is a perspective view showing the use of subsea winches for the placement of the subsea structure upon a blowout preventer or a wellhead on the seabed.
DETAILED DESCRIPTION OF THE INVENTION
(13) FIG. 1 shows the system 10 of the present invention as employed in association with a blowing well 12 located on seabed 14. It can be seen that the blowing well 12 emits a plume 16 of hydrocarbons that will flow in a conical shaped manner toward the surface 18 of the body of water 20. Typically, the blowing well 12 can either be blowing at the wellhead itself or outwardly of a blowout preventer.
(14) Importantly, the present invention can also be used so as to install or remove a subsea structure and a non-vertical manner. In certain circumstances, there may be no plume that is released from a blowing well. Within the concept of the present invention, there can be obstacles to the vertical deployment or removal of the subsea structure. These obstacles can be items such as a rig or other structure affixed within the body of water above the wellhead. As such, access to the well, under those circumstances of a blowing well or under those circumstances of obstacles, needs to be carried out in a non-vertical manner. The present invention is intended to provide access for the installation or removal of a subsea structure from a location laterally offset from the wellhead.
(15) FIG. 1 shows that there is a plurality of barges 22, 24, 26 and 28 that are connected in end-to-end relationship so as to have a linear formation. A primary vessel 30 is connected to the barge 28. Primary vessel 30 is in the nature of a tugboat and is configured so as to properly move the barges 22, 24, 26 and 28 into a desired position within the plume 16. There is a pair of secondary vessels 32 and 34 that are connected by mooring lines 36 and 38 to the end of the barge 22. Winches will be located on the secondary vessels 32 and 34 so as to create tension in the respective mooring lines 36 and 38. Once tension is created in the mooring lines 36 and 38, the plurality of barges 22, 24, 26 and 28 can be maneuvered to a desired position within the exclusion zone 40 of the plume 16. The secondary vessels 32 and 34 will extend at a 120 angle with respect to the linear formation of barges 22, 24, 26 and 28 so as to triangulate the end 42 of the plurality of barges within the primary vessel 30 and the pair of secondary vessels 32 and 34. The pair of secondary vessels 32 and 34 will extend to an approximately 120 angle with respect to the plurality of barges 22, 24, 26 and 28. As such, the end 42 of barge 22 will be positioned generally directly above the wellhead 12.
(16) The barge 22 will have a downline 64 (see FIG. 4) extending downwardly from the end 42. Downline 64, along with an associated hoisting and lowering mechanism, will facilitate the ability to install or remove the capping stack on or from the blowing well 12.
(17) In FIG. 1, it can be seen that the primary vessel 30 and the secondary vessels 32 and 34 are positioned outside of the exclusion zone 40 of the plume 16. As such, the personnel onboard these vessels 30, 32 and 34 will be away from the danger zone. The primary vessel 30 is illustrated as being upwind of the plume 16. The secondary vessels 32 and 34 are illustrated as being downwind of the plume 16. So as to avoid potential toxic effects to personnel aboard vessels 30, 32 and 34, the vessels will be equipped with gas detection equipment and water curtains. The barges are also equipped with gas detection devices and water curtains. All of the vessel positioning is performed outside the surface boil location in calm waters. As such, through the use of the barges 22, 24, 26 and 28, in combination with the vessels 30, 32 and 34, the downline and hoisting equipment associated with the barge 22 can be carried out without the need for personnel ever entering the surface boil area. If the gas detection devices should sense a toxic level of gas in the area, then the vessels can move to a better location or the winches onboard the vessels 32 and 34 can extend the mooring lines further away from the end 42 of the barge 22.
(18) FIG. 2 is a plan view showing the deployment of the vessels 30, 32 and 34 relative to the plume 16. It can be seen that the barge 22 has its end 42 positioned generally at the center of the plume 16. The mooring lines 36 and 38 extend outwardly from the end 42 of the barge 22 at approximately 120 angle. This angle can be adjusted, as needed, depending on wind or current conditions. Also, if necessary, additional secondary vessels can also be used.
(19) FIG. 2 shows that there is a deployment vessel will also carry the capping stack thereon. The deployment vessel 50 further will have adequate wire capacity and length to handle the capping stack weight. The deployment vessel also has a suitable winch thereon. The deployment vessel 50 will always be outside of the plume 16. The deployment can be a separate vessel or one of the primary and secondary vessels.
(20) FIG. 3 illustrates the deployment of the system 10 of the present invention in a calm water surface outside the blowout plume area. In particular, the primary vessel 30 will move with the direction of the wind and current. The barges 22, 24, 26 and 28 are secured to the primary vessel 30 in end-to-end relationship. As such, the primary vessel 30 will move the joined barges 22, 24, 26 and 28 in the manner of conventional barge movement. The deployment vessel 50 will travel in the direction of the wind and current to the deployment location. The deployment vessel 50 can include an overboarding chute to assist in recovery and deployment. The winch onboard the deployment vessel 50 includes sufficient wire to remove/deploy the required payloads at the appropriate depth for the incident well site. The mooring lines 36 and 38 should have a sufficient length in order to allow the secondary vessels 32 and 34 to position the equipment deploying barges in the plume while maintaining station keeping ability of any other vessels with operation personnel onboard outside the plume.
(21) FIG. 4 shows an initial step in the process of the present invention. In FIG. 4, the primary vessel 30 is illustrated as positioned at an end of the plurality of barges 60. The plurality of barges 60 are located at the surface 18 of the body of water 20. The deployment vessel 50 is shown as positioned away from the end 62 of the plurality of barges 60. FIG. 4 shows that there is a downline 64 extending from the end 62 of the plurality of barges 60. The deployment vessel 50 has a crane and winch 66 thereon. Crane and winch 66 has the capping stack 72 connected thereto. An ROV 68 is illustrated as extending downwardly from the deployment vessel 50. The ROV 68 is positioned near the downline 64.
(22) FIG. 5 shows the deployment vessel 50 in a position whereby the crane and winch 66 is configured so as to lower the capping stack 72 over the side of the deployment vessel 50. Similarly, the ROV 68 is in a suitable position for acting on the capping stack 72 as it is lowered. The end 62 of the plurality of barges 60 has the downline 64 extending so as to be adjacent to the seabed 70.
(23) FIG. 6 shows a further step in the deployment of the capping stack 72. In particular, the crane and winch 66 lowers the capping stack 72 into the water 20 and toward the seabed 70.
(24) In FIG. 7, it can be seen that the ROV 68 has grasped the capping stack 72 and has moved the capping stack in a direction toward the downline 64 from the plurality of barges 60. A suitable hoist mechanism 74 on the plurality of barges 60 allows for the remote manipulation of the downline 64. The ROV will secure the downline 64 to the capping stack 72. The line 76 extending from the crane and winch 66 can then be relaxed and released from the capping stack 72.
(25) FIG. 8 shows that the ROV 68 moves the capping stack 72 into a desired position over the wellhead 78. The downline 64 can then be lowered from the plurality of barges 60 so that the ROV 68 can manipulate the capping stack 72 so as to be positioned over the mandrel of a blowout preventer or over the wellhead. The downline 64 can then be released from the capping stack 72 and the capping stack 72 can be installed onto the blowout preventer or the wellhead in a conventional manner. The downline 64 can then be returned back to the barge 66.
(26) All of the operations described in FIGS. 4-8 are carried out by personnel outside of the plume. As such, it is not necessary for personnel to be exposed to the hazardous environment at the plume. The barges, which have no personnel thereon, can simply be positioned into the plume so that the necessary operations associated with the downline and the manipulation of the capping stack at the wellhead can be carried out. The ROV can carry out all of the operations associated with the proper movement of the capping stack so that the capping stack can be properly secured to the blowout preventer or the wellhead. After installation, the capping stack can be operated so as to properly control the blowing well or to stop the blowing well.
(27) FIG. 9 shows the system 100 of the present invention within the gas plume 102. As can be seen, the plurality of barges 104 are located within the plume 102 within the plume at the surface 106 of the sea. The downline 108 extends from the barge at the end of the linear array of barges (as described herein previously). Downline 108 is connected to a shock absorber 110. Another downline 112 extends from the bottom of the shock absorber 110 to the subsea structure 114.
(28) The shock absorber 110 is a passive heave compensator. This is a spring-damper system based on gas pressure and hydraulic fluid. The shock absorber 110 is generally connected between the crane/winch hook and the payload 114 in order to reduce the dynamic load on the hoisting system, the payload and the crane tip. The shock absorber 110 is a standalone system. No external connection of hydraulic/pneumatic hoses or wires are required. This shock absorber 110 is a commercially available unit that by Cranemaster which are certified for subsea lifting operations up to a 3000 meter water depth.
(29) FIG. 10 is an illustration of the shock absorber 110. Shock absorber 110 has a first padeye 116 at the upper end thereof and another padeye 118 at a lower end thereof. Padeye 116 is secured to downline 108. Padeye 118 is secured to the downline 112. Central chamber 120 has a piston-and-cylinder arrangement therein. The side containers 122 and 124 have a gas supplied therein. A nozzle 140 will be positioned between each of the tanks 122 and 124 and the central piston-and-cylinder assembly. FIG. 11 shows the configuration of the shock absorber 110. It can be seen that the central chamber 120 has a cylinder 126 and a piston 128. A vacuum is located within the cylinder 126. Hydraulic fluid 130 is provided on one side of the piston 128. This hydraulic fluid 130 will resist abrupt movements on the piston rod 132 as a result of rough sea conditions affecting the load 134. The gas 136 in the side chamber 138 will further serve to dampen the movements of the load 134. A nozzle 140 is positioned between the gas chamber 138 and the piston-and-cylinder chamber 120.
(30) Under certain circumstances, it is necessary to accurately move the subsea structure onto the blowout preventer or wellhead. FIG. 12 shows one technique for achieving this accurate movement. As shown in FIG. 12, the ROV has moved the subsea structure 150 into a position adjacent to the blowout preventer 152. The plume 154 prevents a very accurate movement of the subsea structure 150 on to the mandrel of the blowout preventer 152. As such, FIG. 12 shows that there is an adapter spool 156 secured to the mandrel of the blowout preventer 152. The adapter spool 156 has a plurality of sheaves extending outwardly from the bore of the spool. A plurality of winches 158, 160 and 162 are disposed on the seafloor 164. Winches 158, 160 and 162 have respective lines 164 extending therefrom. Lines 164 will engage with slings 166 extending from the subsea structure 150. The winches 158, 160 and 162 are actuated so as to pay in the lines 164 around the sheaves of the adapter spool 156 so as to draw the slings 166 from the subsea structure 150 toward the mandrel of the blowout preventer 152. As such, the system (as described in a co-pending patent application) can achieve a proper placement of the subsea structure 150 on the blowout preventer 152 despite the rough sea conditions caused by the plume 154 and/or the combination of uplift force and disturbing movement caused by the blowout plume. The ROV can move the subsea structure 150 into a position adjacent to the blowout preventer 152. The winches 158, 160 and 162 due the remainder of the work. Ultimately, when the connector of the subsea structure 150 is positioned directly above the mandrel of the blowout preventer 152, the winches 158, 160 and 62 will continue to move so as to move the subsea structure 150 until the connector is engaged with the mandrel of the blowout preventer 152.
(31) With reference to the above figures, the process of the present invention can also be used for the removal of subsea structures at the seabed adjacent to the wellhead. This is also carried out in a non-vertical manner. In this process, the plurality of barges are secured together in a linear formation and one end of the plurality of barges is connected to the primary vessel. The primary vessel moves such that at least one of the plurality of barges is positioned over a target or over the subsea structure adjacent to the well. The plurality of secondary vessels are connected by a plurality of mooring lines adjacent to an opposite end of the plurality of barges. These mooring lines are tensioned so as to fix a position of the opposite end of the plurality of barges. The deployment vessel is positioned away from the plurality of barges. An ROV is deployed from the deployment vessel. The ROV is manipulated so as to connect the subsea structure to the downline. The downline and the subsea structure are lifted toward the plurality of barges. The plurality of barges can then be moved such that the deployment vessel can retrieve the subsea structure.
(32) Under certain circumstances there may be no blowing well and no plume from the blowing well. However, it is necessary to provide non-vertical installation or removal of a subsea structure because of an obstruction in the body of water. This obstruction would prevent the vertical installation of such equipment. As such, in the present invention, the end of the plurality of barges can be positioned by the primary vessel in a location generally above the target or subsea structure. The end of the plurality of barges will be away from the obstruction in the water. As such, the same steps, as described hereinabove, can be carried out so as to install or remove the subsea structure.
(33) The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the described process can be made within the scope of the present claims without departing from the true spirit of the invention. The present invention should be limited to the following claims and their legal equivalents.
