NO343218B1 - Procedure for retrieving and deploying underwater equipment - Google Patents

Abstract

A method, comprising providing a first vessel floating on a surface of a body of water; connecting a first cable from the first vessel to a subsea structure; lifting the underwater structure of the water body; connecting a second cable from a second vessel to the subsea structure; disconnect the first cable from the subsea structure; and lifting the subsea structure of the other vessel with the second cable.

Description

BACKGROUND OF THE INVENTION

Field of the invention

The invention relates to systems and methods for installing and/or pulling underwater components without the use of a drilling rig.

Known technique

Today, subsea equipment (eg submersible pumps, headers and trees) can be deployed and/or towed using a semi-submersible drilling rig. The drilling rigs are typically designed to lift the underwater equipment from the seabed to the surface using ropes and cables. Once the subsea equipment has reached the surface, it can be lifted through an opening in the middle of the rig (eg a lower deck opening) and onto the deck of the drilling rig. The underwater equipment that is towed or deployed can therefore be vulnerable to damage during transport. Also, drilling rigs are extremely expensive to operate, costing around $600,000-$800,000 per day to rent and operate. Furthermore, the transport of drilling rigs is slow compared to other floating vessels (e.g. ships, tugs), which can increase the time it takes to tow and/or deploy the underwater equipment. There is thus a need for an efficient and low-cost system for pulling and/or deploying underwater equipment.

US patent application 2003/0221602 shows an alternative for the deployment and installation of underwater equipment using a workboat or other available vessel. The equipment is not supported directly by the vessel, but is instead supported by one or more buoys below the wave zone. The buoys are controlled by a combination of chain, cables and plastic ropes that connect them to the work boat. The buoy system described there thus decouples the vessel's movement from the payload by supporting the payload from the buoys below the wave zone. Since the buoys are located below the wave action and its associated turbulence, there is little energy and thus little tendency to move. The result is a stable, inexpensive maneuverable system capable of operating large underwater payloads over a wide range of water depths.

The US patent 7,314,084 shows a system comprising a pump module connected to an intermediate flow inlet, where the intermediate flow inlet is connected to a base structure arranged on the flow pipe carrying production from one or more oil wells and thereby enables quick and easy installation or retrieval of an underwater pump module with rope from a low-cost vessel. The patent also provides for hydraulic isolation of the subsea pump module by means of cut-off valves on the intermediate flow inlet, whereby the pump module can be easily installed or removed without causing an underwater oil spill. The sealing of the connection is of a metallic type. It is also possible to pass a spike through the system to clean the flow pipes.

US patent 7,150,325 shows an underwater pump unit arranged on a seabed to pump well fluid from seabed wells to the surface. The pump unit has a tubular outer housing which is at least partly buried in the seabed. A tubular primary housing is located inside the outer housing and has a lower end with a container. An annulus surrounds the primary housing within the outer housing to deliver fluid to a reservoir at the lower end of the primary housing. A capsule is lowered into and pulled from the primary housing. The capsule forms sealed engagement with the container to receive well fluid from the annulus. A submersible pump is placed inside the capsule. The pump has an inlet that receives well fluid and an outlet that feeds out well fluid outside this capsule. The capsule has a valve in its inlet which, when closed, prevents leakage of well fluid from the capsule. The capsule can be pulled up through open water without a riser.

US patent application 2005/0220645 discloses an auxiliary pumping system for the production of hydrocarbons from a subsea production well. The auxiliary pump system includes: (1) a submersible pump hydraulically connected to the production well to supply energy to the hydrocarbon flow and increase production to another destination such as a subsea or surface production facility via a riser; (2) an inlet channel to receive the flow from the production well and isolate the flow from the "dummy" wellbore and direct the flow to the pump inlet; and (3) a motor exposed to the dummy wellbore to drive the pump. The dummy well may be flooded or circulated with seawater to cool the engine.

US patent application 2006/0118310 discloses a subsea production system for the production of petroleum by artificial lift, assisted by submersible centrifugal pumps upstream of the WCT and installed on the seabed, comprising a pump module with one or more submersible centrifugal pumps, connected in series or in parallel, with a angulation of up to 85 degrees to the vertical, where the module can be connected to a flow base to enable production "circulation" and where the pump module and flow base can be connected for installation and retrieval by rope. A production line is connected upstream of the upstream pump module and another production line is connected downstream of the pump module. A procedure for installing the system in a new wellhead is described, in addition to a procedure for installing the system in an existing wellhead. Use of the subsea production system for pressure boosting in multiphase flow, injection of water into an injector well and transfer of oil between two collection points is also described.

The US patent application 2008/0314598 shows a system for installing a long underwater module using a vessel, which uses ropes for installation and/or pulling this, as well as methods that are used in the system. The system makes it possible to transport the underwater module on the vessel to a location at sea and lower the underwater module into the sea in a vertical position for installation on the seabed.

Summary of the invention

According to the present invention, a method as stated in claim 1 has been provided for retrieving and deploying underwater equipment. One aspect of the invention provides a method comprising providing a first vessel floating on a surface of a body of water; connecting a first cable from the first vessel to an underwater structure; lift the underwater structure of the water body; connecting a second cable from a second vessel to the underwater structure; disconnecting the first cable from the underwater structure; and lifting the underwater structure of the second vessel with the second cable.

Another aspect of the invention provides a method comprising providing a first vessel floating on a surface of a body of water; connecting a first cable from the first vessel to an underwater structure; lower the underwater structure in the water body; connecting a second cable from a second vessel to the underwater structure; disconnecting the first cable from the underwater structure; moving the second vessel, the second cable and the underwater structure to a desired installation location; and install the underwater structure at the desired location in the water body.

Brief description of the figures

Figures 1-8 show a system for pulling and/or deploying an ESP (Electrical Submersible Pump) lowering box according to embodiments of the present invention.

Figure 9 shows a view of a drawn ESP lowering box according to embodiments of the present invention.

Detailed description

In one aspect, embodiments described herein relate to a method of hauling and deploying underwater equipment, such as a submersible case for an electric submersible pump (ESP). More specifically, embodiments described here relate to a method for using a workboat and a side deck on a floating production, storage and offloading vessel (FPSO - Floating Production, Storage and Offloading vessel) to tow, deploy and/or overhaul an ESP.

Figure 1:

Figure 1 shows a system for attaching an underwater equipment 100 to a work boat 102 according to embodiments of the present invention. In this embodiment, an underwater equipment 100 is located on and/or below the seabed 101. When repair, upgrading, replacement or other operations known to those skilled in the art require installation, pulling or other intervention, a work boat 102 can be connected to the underwater equipment 100 via a cable 104 and a coupling 103. The work boat 102 can have a lifting device 116 such as a crane, winch, hoist or other lifting device known to the person skilled in the art. The cable 104 is preferably a high tensile strength, high strength to weight ratio cable, such as a torque balanced steel cable, but it may also include chains, ropes, wire, cables, or other pulling or deployment devices known to those skilled in the art. The coupling 103 may be a threaded coupling, a press-fit coupling, a swivel, a hook or another connection device known to those skilled in the art. In one embodiment described herein, the connector 103 may connect the cable 104 to a substantially inflexible structure attached to the body of the underwater equipment 100. In another embodiment described herein, the connector 103 may additionally connect the cable 104 to a wire/cable or series of wires/cables connected to the underwater equipment 100. Those skilled in the art will know the wide variety of available lifting devices, cables and connectors that are available and can be used to attach the underwater equipment 100 to the workboat 102 without removing itself from the frame of the embodiments described herein.

In one embodiment, the underwater equipment 100 may be located below the seabed, such as a sump separator, a submersible pump or other known equipment. In another embodiment, the underwater equipment 100 can be located above the seabed, such as an underwater separator, a wellhead, a Christmas tree, a collecting pipe or other known equipment.

Figures 2 & 3:

Figures 2 and 3 illustrate a system for pulling the subsea equipment 100 from the wellbore and transporting the subsea equipment 100 to an FPSO 106. In one embodiment, the subsea equipment can be removed from a well frame arranged in a main wellbore.

The lifting device 116 on the workboat 102 lifts the underwater equipment 100 from the wellbore by pulling on the cable 104. The lifting device 116 can be a winch, a crane, a heave-compensated lifting system or other lifting devices known to the person skilled in the art. The retrieval of the cable may be at a transport depth at which the workboat 102 transports the underwater equipment 100 to the FPSO 106. The transport depth may be determined by safety factors such as underwater formations, technical installations, water currents, conditions on the water surface, weather, transport speed, the capacity of equipment or other factors that may affect transport depth. The depth can also be determined by economic factors, such as the efficiency of the workboat, the number of crew members, wear and tear on equipment or other factors that can affect operating costs. In one embodiment, a suitable transport depth for the bottom of the underwater equipment 100 may be from about 100 to about 500 meters, for example from about 250 to about 350 meters.

Figure 4:

Figure 4 illustrates a system for pulling the underwater equipment 100 to a drop-off depth. The drop-off depth is the depth where a second cable is connected to the lowering box, and may or may not be the same as the transport depth. The second cable during retrieval, for example, may be a cable 108 connected to an FPSO 106. The drop-off depth may be determined by water currents, surface conditions, weather conditions, equipment operating depth, or other factors known to those skilled in the art. The lifting device 116 on the workboat 102 can pull the lower case 100 by adjusting the length of the cable 104 to a certain depth by pulling in or feeding out a length of the cable 104. A cable 108 connected to the FPSO 106 can then be fed out to a drop-off depth that is at least as long or as deep as the suspended workboat cable 104. The FPSO cable 108 is attached to a lifting device 216, such as a crane, winch, hoist or other lifting device known to those skilled in the art. The FPSO cable 108 may be a rope, wire, chain, or other pulling or deployment device known to those skilled in the art.

In one embodiment, a suitable drop-off depth for the bottom of the underwater equipment 100 may be from about 100 to about 500 meters, for example from about 200 to about 400 meters.

Although an FPSO 106 is illustrated in Figure 4, other floating systems may also be used to tow the equipment 100, such as a loading buoy, TLP, semi-submersible rig, a ship, or other floating anchored or unanchored moorings for drilling for and/or production of oil and gas.

Figure 5:

Figure 5 shows a system for connecting the underwater equipment 100 to the FPSO 106 according to embodiments of the present invention. Initially, the workboat 102 and the associated cable 104 support the loads from the underwater equipment 100. The lifting device 216 of the FPSO 106 is attached to a first end of the cable 108. A free end of the line 108 hangs down in the water and has an FPSO coupling 203. A manned underwater vessel , such as a submarine, or an unmanned underwater vehicle (UUV), such as a remotely operated vehicle (ROV) 110, may be used to attach the FPSO cable 108 to the underwater equipment 100 via the FPSO connector 203.

In one embodiment described herein, the connector 203 may connect the cable 108 to a substantially rigid structure attached to the body of the subsea equipment 100. Additionally, in other embodiments, the FPSO connector 203 may connect the cable 108 to a wire/cable or sequence of wires/cables connected to the subsea equipment 100. The FPSO coupling 203 may be a threaded coupling, a press fit coupling, a swivel, a hook or any other connection device known to those skilled in the art. The FPSO connector 203 may, but need not, be the same type of connector as the workboat connector 103. In one embodiment of the present invention, the FPSO connector 203 may connect the FPSO cable 108 to the same pulls on the subsea equipment 100 as the workboat connector 103, where the feature can be, as described above, a mainly rigid structure, a wire/cable or another element on the underwater equipment 100.

In another embodiment described herein, the FPSO connector 203 may connect the FPSO cable 108 to another pull on the subsea equipment 100 located in a different location or with a different orientation than the workboat connector 103. Furthermore, the ROV 110 may be used to monitor and/or or assist when lowering, raising and/or positioning equipment in the water.

In one embodiment, the workboat connector 103 may be connected to the top of the equipment 100 , while the FPSO connector 203 may be connected to the bottom of the equipment 100 so that the equipment 100 is turned upside down when the FPSO cable 108 is pulled.

Figure 6:

The embodiment in Figure 6 shows a system for transporting the underwater equipment 100 from the workboat 102 to the FPSO 106. After the FPSO cable 108 is attached to the coupling 203 on the sinker 100, for example with an ROV 110, the underwater equipment can be transported from the workboat to the FPSO one. The transport of the cargo can be done by increasing the length of the workboat cable 104, reducing the length of the FPSO cable 108 or a combination thereof. Adjustment of the length of the FPSO cable 108 and/or the workboat cable 104 can be done using the lifting devices 116, 216 (Figure 4) provided on the FPSO 106 and the workboat 102. When the length of one of the FPSO cable 108 or the workboat cable 104 has been increased/reduced, so that the FPSO cable 108 or the workboat cable 104 is longer than the other cable, the load from the sinking box is transferred to the structure, i.e. the workboat 102 or the FPSO 106, which has the shortest cable. When the FPSO cable 108 is in tension as a result of it supporting the load from the sinking casing 100, the ROV 110 can disconnect the workboat cable 104 from the underwater equipment 100, or the workboat cable 104 can be disconnected by the crew of the FPSO 106 when the equipment 100 is brought up to FPSO 106.

Figure 7:

Figure 7 illustrates a system for lifting the underwater equipment 100 to a support platform 112 on the FPSO 106. The lifting device 216 on the FPSO 106 can lift the underwater equipment 100 by reducing the length of the FPSO cable 108 that descends into the sea. In addition, the length of the cable 108 can be reduced by pulling on the cable 108 with a winch or various other devices known to those skilled in the art. The top of the underwater equipment 100 can be raised above the water surface.

Figure 8:

The embodiment in Figure 8 shows a system for attaching the underwater equipment 100 to the FPSO 106. The underwater equipment 100 is suspended from the lifting device 216. In the shown embodiment, the lifting device 216 is a crane system, but as indicated previously it can also be a winch, hoist or other lifting device known to the person skilled in the art without departing from the scope of the present invention. The subsea equipment 100 may be maneuvered by any necessary mechanism in a translational or rotational motion to land the equipment 100 within a mounting bracket 118. The mounting bracket 118 is attached to the side of the FPSO 106 and is adapted to receive and secure the subsea equipment 100 to the FPSO 106. Those skilled in the art will know that many types of brackets and locking mechanisms can be used to secure the underwater equipment without removing itself from the framework of the present invention.

Figure 9:

Figure 9 shows a view of a towed underwater equipment 100 placed on the support platform 112 of the FPSO 106. The underwater equipment 100 can be repaired, upgraded, stored, overhauled or replaced on the deck of the FPSO 106. The lifting device 216 can be disconnected and used for other operations.

Deployment of equipment:

In addition, with general reference to Figures 1-9, a method similar to those described above can be used to deploy an underwater equipment 100. During deployment, the underwater equipment 100 is connected to the lifting device 216 on the FPSO 106 via a cable 108. The connection 203 can be one of many different types described above. The underwater equipment 100 can be detached from the bracket 118 and lowered to the drop-off depth. The lifting device 116 arranged on the workboat 102 lowers the cable 104 at least to the delivery depth. The ROV 110 may attach the workboat cable 104 using any suitable coupling 103 known to those skilled in the art. The load from the underwater equipment 100 can be transferred from the FPSO 106 to the workboat 102 by feeding out the FPSO cable 108, pulling in the workboat cable 104 or a combination of these two. The ROV 110 can then disconnect the FPSO cable 108 from the coupling 203 and the workboat 102 can feed out or pull in the cable 104 to position the subsea equipment 100 at a transport depth. The workboat 102 transports the underwater equipment 100 to the well hole, where the workboat cable 104 is fed out to lower the underwater equipment 100 closer to the seabed 101. The underwater equipment 100 can be maneuvered, e.g. of an ROV, and further length of cable 104 can be fed out to secure the underwater equipment 100 in the wellbore. The workboat cable 104 is then disconnected from the connector 103.

Examples of designs:

Embodiments described herein usefully provide a method for pulling and deploying underwater equipment without the use of a rig. A system according to embodiments described here can thus free up more space and resources for other operations on the rig. In addition, the method may enable the hauling and deployment of subsea equipment for repair or replacement that is not located in the vicinity of a rig or FPSO. Finally, the method may use nearby equipment, such as a workboat, an FPSO, lifting devices, cables and couplings to perform a new task.

In one embodiment, a method is shown comprising providing a first vessel floating on a surface of a body of water; connecting a first cable from the first vessel to an underwater structure; lift the underwater structure of the water body; connecting a second cable from a second vessel to the underwater structure; disconnecting the first cable from the underwater structure; and lifting the underwater structure of the second vessel with the second cable. In some embodiments, the first cable from the first vessel to the underwater structure is connected to at least one underwater buoy to isolate the heave motion of the first vessel from the underwater structure. In some embodiments, the method also comprises supporting the underwater structure with a platform on the second vessel, and further comprises disconnecting the second cable from the underwater structure. In some embodiments, the method also comprises lifting the underwater structure onto a deck of the second vessel. In some embodiments, the method also comprises transporting the underwater structure to land. In some embodiments, the first vessel comprises a workboat with at least one of a winch and a crane. In some embodiments, the second vessel comprises an FPSO. In some embodiments, the underwater structure comprises an electric submersible pump. In some embodiments, the method also comprises transporting the underwater structure with the first vessel towards the second vessel over a length of from 5 kilometers to 100 kilometers.

In one embodiment, a method is shown comprising providing a first vessel floating on a surface of a body of water; connecting a first cable from the first vessel to an underwater structure; lower the underwater structure in the water body; connecting a second cable from a second vessel to the underwater structure; disconnecting the first cable from the underwater structure; moving the second vessel, the second cable and the underwater structure to a desired installation location; and install the underwater structure at the desired location in the water body.

Although the invention has been described in connection with a limited number of embodiments, the person skilled in the art will, on the basis of this description, understand that other embodiments can be constructed which do not depart from the scope of the invention as explained here. The scope of the invention shall therefore only be limited by the appended claims.

Claims (8)

Patent claims 1. Procedure for retrieving and deploying underwater equipment, including: providing a first vessel floating on a surface of a body of water; and connecting a first cable (104) from the first vessel to an underwater structure (100); characterized by lifting the underwater structure (100) in the body of water to a transport depth of between 100 and 500 meters; transporting the underwater structure (100) with the first vessel towards a second vessel over a distance of from 5 kilometers to 100 kilometers; connecting, at a hand-off depth of between 100 and 500 meters, a second cable (108) from a second vessel to the underwater structure (100); disconnecting the first cable from the underwater structure (100); and lifting the underwater structure (100) of the second vessel with the second cable (108). 2. Method according to claim 1, wherein the first cable (104) from the first vessel to the underwater structure (100) is connected to at least one underwater buoy to isolate the heaving movement of the first vessel from the underwater structure (100). 3. Method according to one or more of claims 1-2, further comprising supporting the underwater structure (100) with a platform on the second vessel, and further comprising disconnecting the second cable from the underwater structure (100). 4. Method according to one or more of claims 1-3, further comprising lifting the underwater structure (100) onto a deck of the second vessel. 5. Method according to one or more of claims 1-4, further comprising transporting the underwater structure (100) to land. 6. Method according to one or more of claims 1-5, where the first vessel comprises a workboat (102) with at least one of a winch and a crane. 7. Method according to one or more of claims 1-6, where the second vessel comprises an FPSO (106). 8. Method according to one or more of claims 1-7, where the underwater structure (100) comprises an electrically submersible pump.