Patent Grant
7628568
This invention relates in general to the conveyance of hydrocarbons from a subsea well or wells, and in particular to an apparatus and assembly, and methods associated therewith, for conveying the hydrocarbons from a subsea flowline to a floating production unit or vessel at the surface.
When conveying hydrocarbons from a subsea well to a vessel at the surface, the hydrocarbons are often communicated through flowlines and risers extending along the surface of the sea floor. The flowline is the part resting on the sea floor and the riser is the piece that connects the flowline to the floating production unit or vessel at the surface. The flowline can be extending from a single subsea wellhead, from subsea processing equipment, or from a subsea collection manifold.
In one previous arrangement, a steel catenary riser (SCR) is an extension of the flowline or pipeline from the sea floor to a hang-off location in the floating production unit or vessel at the surface. Such an arrangement required very long risers such that the steel riser could rise gradually in a catenary shape from the sea floor to the surface of the sea.
In another previous arrangement, a vertical riser, typically also made of steel, extends from a subsea base toward the surface of the sea. The riser can extend to a surface vessel, or to a buoy that is located at, or just under the surface of the sea for connection with floating production unit or vessel at the surface. In one standard arrangement with a submerged buoy, the buoy is approximately fifty (50) meters below the sea surface such that a vessel does not damage the buoy if it travels over the buoy. In this arrangement, the submerged buoy provides an upward lift on the riser such that the riser extends substantially vertical relative to the sea floor. The subsea flowline or pipeline connects to the riser through a subsea jumper in order to communicate the hydrocarbons from the flowline or pipeline to the riser. Typically, because the flowline or pipeline is installed prior to the riser and riser base, the subsea jumper is fabricated pursuant to measurements taken on site. Such measurements, fabrication, and installation can be timely and labor intensive.
The floating production unit or vessel at the surface connects to the vertical riser via a flexible flowline jumper. The flexible flowline jumper communicates the hydrocarbons from the riser to the floating production unit or vessel. A mooring assembly helps to ensure that the floating production unit or vessel stays on location within predetermined distances relative to the buoy so that movement of the floating production unit or vessel due to tidal drift or wind does not damage the riser assembly.
Installation of the vertical riser assemblies followed the following steps. Initially, the flowline or pipeline is installed independently from the riser. The flowline or pipeline typically has a flowline end or a pipeline end termination (PLET) with a connector for jumper installation. The flowline or pipeline is typically installed using either an S-lay, J-lay, or Reel installation vessel. The riser base or foundation is then installed adjacent the flowline end or PLET. A typical riser base is a conventional foundation, such as a “suction pile” as is readily known to those skilled in the art, with interface for vertical riser connection at the top of the pile.
After the installation of the flowline or pipeline and the riser foundation is complete, the riser is installed separately. Typically, the riser is installed using a J-lay vessel that vertically deploys the riser and a riser latch onto the riser base. After the riser is installed and latched onto the riser base, the buoy is connected to the upper end of the riser to provide the upward support of the riser. After subsea measurement, the subsea jumper is then fabricated and installed in order to connect the flowline or pipeline with the riser in fluid communication.
The floating production unit or vessel then is transported and moored in the field. The flexible jumper is then installed between the FPSO and the riser, preferably with a riser interface positioned at an upper end portion of the riser. The operator then hydrotests and pre-commissions the riser assembly prior to actuating valves to allow the hydrocarbons to communicate through the flowline, the subsea jumper, the riser, and the flexible jumper, to the floating production unit or vessel at the surface.
Accordingly, in the prior vertical riser arrangement there were several distinct steps that were required for installation of the riser assembly: 1) install the flowline; 2) install the riser foundation; 3) install the riser assembly; 4) subsea measure, fabricate and install the subsea jumper between the flowline and the riser; 5) install or moor the floating production unit or vessel; 6) install the flexible surface jumper between the riser and the floating production unit or vessel; and 7) hydrotest and pre-commission the riser assembly.
The invention comprises a method to install flowline or pipelines and risers using the hinge-over joint device that links the flowline and pipeline with riser which allows the new proposed installation method to take place.
A method for installing a subsea flowline and riser assembly on a sea floor includes providing a flowline having a flowline axis and an end connected to a hinge-over joint, and a riser having a riser axis and an end connected to the hinge-over joint such that the axes of the riser and flowline extend substantially parallel to each other. An end of the flowline opposite from the hinge-over joint is lowered to the sea floor. The end of the flowline connected to the hinge-over joint is then also lowered to the sea floor. The hinge-over joint is connected to a foundation that is installed in the sea floor. The riser is rotated about the hinge-over joint such that the riser axis is substantially perpendicular to the flowline axis. A subsea jumper is connected between a flowline opening formed in the flowline and a riser opening formed in the riser so that the riser is in fluid communication with the flowline.
The step of rotating the riser about the hinge-over joint can also include moving an end of the riser opposite from the end connected to the hinge-over joint upward. The riser is rotated in such a manner so that the riser is substantially vertical relative to the sea floor.
In the step of providing the flowline, hinge-over joint, and the riser, the axes of the riser and flowline can extend substantially coaxially. The foundation can be installed prior to the step of lowering the end of the flowline opposite of the hinge-over joint to the sea floor, or after the step of lowering the end of the flowline connected to the hinge-over joint to the sea floor. The method can also include that a remote operated vehicle (ROV) can connect the subsea jumper between the riser opening and the flowline opening.
The step of providing the flowline, hinge-over joint, and riser can also include providing that the hinge-over joint has a movable arm and a joint base. The arm can be pivotally connected to the base and the riser can be connected to the arm. The method can also include locking the arm in a deployment position prior to step lowering the flowline to the sea floor so that the axes of the riser and flowline remain substantially parallel prior to step rotating the riser about the hinge-over joint. The rotating of the riser about the hinge-over joint can further include the step of unlocking the arm prior to rotating the riser about the hinge-over joint, and locking the arm in an operating position so that the axes of the riser and the flowline remain substantially perpendicular prior to connecting the subsea jumper.
A method for installing a subsea flowline and riser assembly on a sea floor includes lowering a first end of a flowline from a floating vessel to the sea floor. A hinge-over joint is then connected to a second end of the flowline. A first end of a riser is then connected to the hinge-over joint, and then the hinge-over joint and the first end of the riser are lowered to the sea floor from the vessel. The hinge-over joint aligns the flowline and the riser such that a flowline axis extending from the second end of the flowline is substantially in-line with a riser axis extending from the first end of the riser. The hinge-over joint is then connected to a foundation installed in the sea floor. A second end of the riser is then lifted in order to rotate the riser about the hinge-over joint, such that the riser axis extending from the first end of the riser traverses or intersects the flowline axis extending from the flowline. With an ROV, a subsea jumper is connected between a flowline opening formed adjacent the second end of the flowline and a riser opening formed adjacent the first end of the riser so that the riser is in fluid communication with the flowline.
The method can also include that the subsea jumper is fabricated prior to the step of lowering the first end of the flowline, pursuant to predetermined dimensions such that the subsea jumper can readily connect between the flowline opening and the riser opening after the riser is lifted to rotate the riser about the hinge-over joint.
In the method, the hinge-over joint can have a movable arm and a joint base, and the second end of the flowline can be connected to the base. The arm can be pivotally connected to the base and the first end of the riser can be connected to the arm. The method can also include locking the arm in a deployment position prior to lowering the hinge-over joint and the first end of the riser to the sea floor. When the riser is being lifted, the method can further include the steps of unlocking the arm prior to lifting the second end of the riser and thereby rotating the riser about the hinge-over joint, and locking the arm in an operating position with the riser axis extending from the first end of the riser traversing the flowline axis extending from the second end of the flowline prior to connecting the subsea jumper with the ROV. The method can also include that the riser axis extending from the first end of the riser is substantially perpendicular with the flowline axis extending from the second end of the flowline when the arm is locked in the operating position.
The method can also include that prior to connecting the hinge-over joint to the foundation, the second end of the riser is lowered to the sea floor, and then the foundation is installed. A further step can include unlocking the hinge-over joint and lifting the end of the riser opposite from the hinge-over joint away from the seafloor, thereby rotating the riser to its final substantially vertical position.
Alternatively, the foundation can be installed prior to lowering the first end of the flowline to the sea floor, and the hinge-over joint is lowered onto the foundation when the hinge-over joint is lowered to the sea floor.
An assembly for transferring hydrocarbons from a sea floor to a vessel at the surface includes a riser that extends substantially vertically relative to the sea floor and a flowline that extends substantially parallel to the sea floor. A hinge-over joint is connected to a foundation installed in the sea floor. The hinge-over joint has a base and a movable arm that is pivotally mounted to the base. The base is connected to an end of the flowline, and the arm is connected to the riser. Prior to the hinge-over joint being connected to the foundation, the arm is in an installation position in which a riser axis is substantially parallel to a flowline axis. After the hinge-over joint is connected to the foundation, the arm is in an operating position in which the riser axis is substantially perpendicular to the flowline axis. A riser opening is formed in the riser adjacent the connection between the riser and the arm, and a flowline opening is formed in the flowline adjacent the connection between the flowline and the base. A subsea jumper extends between the riser opening and the flowline opening so that the riser is in fluid communication with the flowline.
In the assembly, the subsea jumper can be prefabricated prior to the hinge-over joint being connected to the foundation such that the subsea jumper engages the riser opening and the flowline opening when the arm is in the operating position.
In the assembly, the hinge-over joint can have a locking mechanism that is adapted to be actuated by an ROV. The locking mechanism can engage the arm to lock the arm in the installation position prior to the hinge-over joint being connected to the foundation, and to lock the arm in the operating position after the hinge-over joint is connected to the foundation. The assembly can also include that the locking mechanism disengages from the arm when the arm moves from the installation position to the operating position.
In the assembly, an end portion of the flowline opposite from the connection with the base can be adapted to connect to a subsea structure that supplies hydrocarbons. An end portion of the riser opposite from the connection with the arm can be adapted to connect to a surface jumper extending from the vessel.
An assembly for transferring hydrocarbons from a sea floor to a vessel at the surface includes a subsea riser and a subsea flowline. A hinge-over joint is connected to a foundation installed in the sea floor. The hinge-over joint has a stationary member and a movable member mounted to the stationary member. The stationary member is connected to an end of the flowline and the movable member is connected to an end of the riser. The movable member is in an installation position in which a riser axis is substantially parallel to a flowline axis prior to the hinge-over joint being connected to the foundation. The movable member is in an operating position in which the riser axis is substantially perpendicular to the flowline axis after the hinge-over joint is connected to the foundation. A riser opening is formed in the riser adjacent the connection between the riser and the movable member. A flowline opening is formed in the flowline adjacent the connection between the flowline and the stationary member. A subsea jumper extends between the riser opening and the flowline opening with the riser being in fluid communication with the flowline.
Referring to
Vessel 13 lowers a first end portion of a flowline 15 to sea floor 11. This can be in accordance with standard practices, in which a plurality of segments of flowline 15 are each welded to a previous segment which is about to be lowered into the sea in order to form a single flowline of a desired length. The flowline installation begins with a predetermined target area and ends in a predetermined target area. As will be readily appreciated by those skilled in the art, vessel 13 begins lowering the first end portion of flowline 15 a predetermined distance away from the final target area, and sails toward target area as additional flowline segments are added to flowline 15. After the final segment of flowline 15 is welded together, the second end portion of flowline 15 is connected, to a hinge-over joint 17 located on vessel 13.
Hinge-over joint 17 is then also prepared for being lowered to sea floor 11 from vessel 13. Prior to lowering hinge-over joint 17 into the sea, a first end, or first end portion of a riser 19 is connected to an opposite end of hinge-over joint 17 such that hinge-over joint 17 is positioned between flowline 15 and the first segment of riser 19. Preferably, the first end of riser 19 is connected to hinge-over joint 17 with a weld.
As perhaps best shown in
Hinge-over joint 17 and riser 19 are lowered into the sea from vessel 13 until hinge-over joint 17 reaches sea floor 11. Hinge-over joint 17 is then connected to a riser base, riser foundation pile or foundation 25. Foundation 25 is preferably a conventional foundation, such as a “suction pile” as is readily known to those skilled in the art, with interface for vertical riser connection at the top of the pile. However, foundation 25 should not be so limited to exclude unconventional foundations, riser bases, riser foundation piles, so long as they help to anchor the riser to sea floor 11. In the embodiment illustrated in
After hinge-over joint 17 is connected to foundation 25, riser 19 is rotated about hinge-over joint 17. In the preferred embodiment, riser 19 is rotated by sailing vessel 13 in the opposite direction from the direction vessel 13 sailed when lowering flowline 15, hinge-over joint 17, and riser 19. By sailing in the opposition direction, vessel 19 effectively pulls the second end portion of riser 19 upward from sea floor 11 and hinge-over joint 17, thereby causing riser 19 to rotate about hinge-over joint 17. Riser 19 is preferably rotated in such a manner until riser 19 is extending substantially perpendicular to sea floor 11, thereby defining an operational or operating position of hinge-over joint 17, which is illustrated in
Hinge-over joint 17 is then locked in the operational position. After locking hinge-over joint 17 in the operational position, a buoy 27 is connected to buoy connection interface 21. Buoy 27 provides upward lift on riser 19 so that riser 19 remains substantially vertical relative to sea floor 11. A subsea jumper 59 (
The subsea jumper can be a separate component, which is pre-designed, manufactured and tested to be further integrated by an ROV to the hinge-over joint connection points. The subsea jumper can also be a subcomponent part of the hinge-over device, which is activated by ROV to latch on to a final operation position and allow fluid continuity from flowline and riser.
Referring to
Foundation interface 33 is the portion of base 29 that engages foundation 25 when hinge-over joint 17 connects to foundation 25, as shown in
A lock mechanism 45 secures arm 41 in the installation and operating positions of hinge-over joint 17. Lock mechanism 45 preferably includes a locking member 47 that selectively engages first and second lock receptacles 49,51. As shown in
Locking member 47 can retract through simple displacement or through telescoping action of locking member 47. As will be readily appreciated by those skilled in the art, arm 41 is free to move between the installation position and the operating position when locking member 47 is unlocked and free of engagement with either first or second lock receptacles 49,51. In the preferred embodiment, an actuation handle 53 actuates locking member 47 between the locked and unlocked positions. Actuation handle 53 is adapted to be actuated with an ROV for selectively actuating locking member 47 between locked and unlocked positions.
A flowline opening connection or flowline opening 55 is formed adjacent second end portion of flowline 15. Flowline opening 55 is used for connecting a tubular structure or conduit in fluid communication with the interior of flowline 15. A riser opening 57 is formed adjacent first end portion of riser 19. Riser opening connection or riser opening 57 is in fluid communication with the interior of riser 19. In the preferred embodiment, flowline and riser openings 55,57 are separated by a known geometric distance when hinge-over joint 17 is in the operating position. In other words, the three-dimensional distance between flowline opening and riser opening 55,57 for when hinge-over joint 17 is in the operating position is already known and measured.
After connecting hinge-over joint 17 to foundation 25 and locking arm 41 in the operating position, a subsea jumper 59 is installed between flowline opening 55 and riser opening 57. Subsea jumper 59 is preferably a tubular structure, pre-fabricated to extend between and connected to flowline and riser openings 55,57. Typically, subsea jumper 59 is lowered to hinge-over joint 17 with a wireline and connected with an ROV. Alternatively, subsea jumper 59 can be connected to either one of flowline or riser openings 55,57 prior to hinge-over joint 19 being lowered to sea floor 11, and the ROV physically connects subsea jumper 59 to the other of flowline or riser openings 55,57. Further, subsea jumper 59 can also be connected to one of flowline or riser openings 55,57 and the ROV hydraulically actuates the subsea jumper into connection with the other of flowline or riser openings 55,57. For example, subsea jumper 59 can be a built in hydraulic activated telescoping system that retracts to disengage or extend to engage subsea jumper 59 for attainment of fluid continuity between the interior of flowline 15 and interior of riser 19. In either arrangement, connecting flowline and riser openings 55,57 is quicker and easier because subsea jumper 59 is pre-fabricated to extend a known distance, in a known direction in order to connect flowline 15 and riser 19 in fluid communication.
Referring to
After riser 19 and hinge-over joint 17 are in the operating position, lock mechanism 45 is actuated to the locked position with locking member 47 engaging second lock receptacle 51. Subsea jumper 59 and buoy 27 are then installed in the same manner as described for the first embodiment. This embodiment is useful because it allows the flowline and riser installation vessel to go elsewhere and lay other flowline and riser assemblies while waiting for a vessel to install foundation 25.
Referring to
Referring to
The connection 21 at the upper end portion or second end portion of riser 19′ is handed over and finally connected to the structure of the floating production unit. In this embodiment, riser 19′ can be made of steel pipe or flexible pipe. Subsea buoys 61 form an arc-shaped curvature in riser 19′ and help to keep the lowermost end portion of riser 19′ substantially vertical relative to hinge-over joint 17.
While the invention has been shown in only some of its forms, it should be apparent to those skilled in the art that it is not so limited, but susceptible to various changes without departing from the scope of the invention. For example, foundation 25 can be installed adjacent a larger riser foundation, and after rotating riser 19 about hinge-over joint 17, riser 19 can be moved over to and connected with the larger riser foundation. Then a subsea jumper is connected between flowline opening 55 adjacent hinge-over joint 17 and riser opening 57, which is now adjacent the larger riser foundation upon which riser 19 is connected.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4277202 | Archambaud et al. | Jul 1981 | A |
| 4906137 | Maloberti | Mar 1990 | A |
| 5320175 | Ritter | Jun 1994 | A |
| 6854930 | Pionetti | Feb 2005 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20080179064 A1 | Jul 2008 | US |
