WO2010030190A2

WO2010030190A2 - Riserless deep water well intervention system

Info

Publication number: WO2010030190A2
Application number: PCT/NO2009/000316
Authority: WO
Inventors: Henning Hansen
Original assignee: Ziebel As
Priority date: 2008-09-14
Filing date: 2009-09-10
Publication date: 2010-03-18
Also published as: WO2010030190A3

Abstract

A subsea well intervention system (10) includes an intervention rod (12) including at least one of a spoolable fiber reinforced plastic or an armored cable. The intervention rod is disposed on a reel (11), the reel affixable to a structure (HA) proximate a subsea wellhead. The intervention rod has at least one of a conduit, an optical fiber and an electrical conductor therein. A seal device (18, 28) is affixable to the subsea wellhead and is configured to enable sealing travel there through of the intervention rod. The system includes means (15) for remotely operating the reel and seal device from a vessel on the surface of a body of water.

Description

RISERLESS DEEP WATER WELL INTERVENTION SYSTEM Background of the Invention

Technical field The invention relates generally to the field of subsea wellbore production equipment. More specifically, the invention relates to wellbore intervention systems for subsea completed wellbores .

Related Art

Subsea completed wells are wellbores drilled through rock formations below the bottom of a body of water such as a lake or the ocean. Such wellbores typically have a casing or pipe emplaced in the wellbore through the rock formations from which hydrocarbons are withdrawn. Valves and other fluid flow control devices called a "wellhead" may be disposed on the water bottom at the top of the pipe or casing. One or more flexible lines may connect the fluid producing portions of the wellhead to fluid production processing equipment disposed on a vessel floating on the water surface.

It may become necessary during operation of such wells to perform maintenance and/or repair and recompletion operations within the wellbore below the wellhead. Such operations are known in the art as

"intervention" operations. A number of methods for subsea well intervention are known in the art, wherein the intervention into the well is performed from a floating vessel, typically consists of running an armored electrical cable ("wireline") from the vessel through the water into a lubricating system mounted on top of the flow control equipment ("subsea wellhead"). In case of an emergency disconnect of the well from surface equipment, the wireline going into the wellbore may need to be cut, resulting in a costly and complicated fishing operation when the floating vessel is back on location. It is also typically necessary to provide a conduit ( "riser" ) that extends from the subsea wellhead to the vessel at the water surface to provide a guide for the wireline or other instruments to be transported from the surface to the wellbore. Assembly of such riser is difficult and expensive; typically the riser must be assembled from segments coupled together on board the vessel and lowered into the water. A remotely operated vehicle ("ROV") may be used to connect the lowermost end of the assembled riser to the wellhead.

A semi-stiff and εpoolable carbon fiber reinforced plastic rod has been developed by Ziebel AS, Tanager, Norway, the assignee of the present invention for wellbore logging and surveying operations. In operation in a well, the intervention rod can be pushed into the wellbore even against the internal fluid pressure in the wellbore. Pushing the rod eliminates the need for weights to pull devices into the well as is typically necessary using wireline, and as such it reduces the need for a high pressure lubricator system. The Ziebel spoolable rod system contains optical fibers for transmitting signals from sensors used for monitoring wellbore parameters, and can be readily modified to include one or more insulated electrical conductors whereby electrically powered wellbore tools can be operated for performing wellbore maintenance work, perforating, electric logging, setting and retrieving plugs, opening or closing valves and more. There exists a need for subsea wellbore intervention devices that can eliminate the need to assemble a riser from a vessel at the surface to a subsea wellhead. Summary of the Invention

A subsea well intervention system according to one aspect of the invention includes an intervention rod, including a spoolable fiber reinforced plastic, or an armored cable. The intervention rod is disposed on a reel, the reel affixable to a structure proximate a subsea wellhead. The intervention rod has at least one of a conduit, an optical fiber and an electrical conductor therein. A seal device is affixable to the subsea wellhead and is configured to enable sealing travel therethrough of the intervention rod. The system includes means for remotely operating the reel and seal device from a vessel on the surface of a body of water.

A method for conducting intervention operations in a wellbore having a subsea wellhead according to another aspect of the invention includes affixing a reel having a spoolable intervention rod comprising at least one of a fiber reinforced plastic rodorr an armored cable wound thereon proximate the subsea wellhead. A sealing element onto the wellhead, the sealing element enabling sealing passage of the rod therethrough into the wellbore. A command is sent from proximate the surface of a body of water to operate the reel to extend the rod into the wellbore. At least one wellbore intervention operation is conducted proximate the end of the rod.

Brief Description of the Drawings

FIG. 1 shows an example subsea wellbore intervention system including a spoolable semi-stiff rod disposed on a reel.

FIG. IA shows deploying the system of FIG. 1 onto a wellhead from a vessel.

FIG. IB shows remote operation of the system of FIG. 1 after deployment is completed. FIG. 2 shows one example of the spoolable rod. FIG. 3 shows another view of the system shown in FIG. 1. FIG. 4 shows an example of a Y connector used in some examples for inserting long wellbore instruments into the wellbore, for ultimate conveyance using the spoolable rod system of FIG. 1.

FIG. 5 shows another example of a long instrument insertion tube.

FIG. 6 shows an example of a seal system for the spoolable rod.

FIG. 7 shows an example self contained reel operating system.

Detailed Description A self-contained wellbore intervention system as shown in FIG. 1 can be deployed by a vessel (FIG. IA) floating on the water surface (FIG. IA) , where the system is coupled to a subsea wellhead 14 in one or several operations on top of a well to be intervened. The system 10 may be lowered into the water from the vessel, for example, by a winch at the end of an umbilical cable 15 (explained in more detail below with reference to FIGS. IA and IB) . FIG. 1 shows one example of a spoolable, semi- stiff rod type wellbore intervention system 10 deployed on the subsea wellhead 14, wherein the wellhead 14 is disposed on a platform 16 on the seabed 17. The subsea wellhead 14 can be any type known in the art including pressure control devices explained below with reference to FIGS. 4 and 6. In FIG. 1, the intervention system 10 may be mounted on top of the subsea wellhead 14. It should be noted that the intervention system 10 can either be mounted on top of the wellhead 14 as shown in FIG. 1, or it can be placed on the seabed 17 laterally displaced from the wellhead 14. The intervention system 10 may be connected to the wellhead 14 using a remotely operated vehicle ("ROV" - not shown) of the type ordinarily used to assemble a lower marine riser package to a subsea wellhead, among other operations for such ROVs. The intervention system 10 may include a motor operated reel 11 disposed in a suitable frame HA. The frame 11 can be configured to be affixed to the wellhead 14 or the platform 16. The motor (not shown in FIG. 1) may be an electric or an hydraulic motor, for example. Power to operate the motor (not shown in FIG. 1) may be provided in some examples by the umbilical cable 15 that extends from the vessel (not shown in FIG. 1) on the water surface to the system 10. Other examples may provide battery power proximate the reel so that no umbilical cable is needed. The reel 11 may include thereon a semi- stiff, spoolable fiber reinforced plastic rod 12, such as one used to provide well intervention services under the service mark ZIPLOG, which is a service mark of Ziebel AS, the assignee of the present invention. The intervention rod 12 may include one or more fluid conduits, one or more optical fibers for signal communication and one or more electrical conductors for power transmission and signal communication. A non-limiting example of such a spoolable intervention rod is described in U.S. Patent No.- 5,184,642 issued to Delacour. In other examples, the intervention rod may be an armored cable including one or more optical fibers and/or insulated electrical conductors .

The umbilical cable 15 may provide tensile support to raise and lower the system 10 from the vessel (FIG. IA, IB) and in some examples can provide electrical and/or hydraulic power to operate the system 10. The umbilical cable 15 may also have a signal communication channel (e.g., optical fibers and/or electrical conductors) to transmit signals from instruments (not shown in FIG. 1) disposed in the wellbore to a recording device (not shown) on the vessel (FIG. IA) , and/or to transmit signals from such surface devices to the instruments in the wellbore. Prior to mounting the intervention system 10 on the wellhead 14, a device known as a "tree cap" (see 32 in FIG. 4) should be removed. An ROV can also perform such tree cap removal operation. When the system 10 is disposed at the proper location on the wellhead 14 or the sea floor 17, the ROV (not shown) may make the required connections (FIG. 4) between the system 10 and the wellhead 14.

FIG. IA shows the vessel 2 on the surface of the water 1, lowering the system 10 by the umbilical cable 15 using a winch 3. The system 10 is lowered until it is disposed above or adjacent to the wellhead 14 as explained above. An ROV (not shown) may make final positioning adjustments and may make the connections between the system 10 and the wellhead or platform. After the system 10 is suitably coupled to the wellhead or platform, in some examples a connector 15A on the distal end of the umbilical cable 15 may be uncoupled, and the umbilical cable 15 may be withdrawn from the water 1. In some examples, the system 10 may be operated remotely using commands transmitted through the water. FlG. IB shows the system 10 disposed on the wellhead 14 wherein signals are communicated through the water using acoustic transducers on the system, shown at 15B and on the vessel 2, shown at 15C. A more detailed example of a battery powered, self contained system for operating the intervention rod 12 will be explained with reference to FIG. 7.

FIG. IB also illustrates portions of the wellbore 45 below the wellhead 14. The wellbore 45 may be drilled to a selected depth in the formations below the water bottom IA. A casing 43 may be cemented in place in the wellbore 45. A surface pipe or casing 43 may be disposed externally to the casing 45 and may seal shallow formations and provide a mounting place for the wellhead 14. The intervention rod 12 is shown disposed partially in the wellbore 45 with an intervention tool 24A disposed at the lower end thereof. The intervention tool 24A will be explained in more detail below with reference to FIG. 4 and FIG. 5.

Returning to FIG. 1, the reel 11 may include a rotary coupling (not shown) that enables connection of fiber optic data and command signal lines, electrical power and signal lines as well as hydraulic lines (see FIG. 2) in the spoolable rod 12 to a rotationally fixed device, in particular the umbilical cable 15. Such rotary coupling (not shown) may be of any type known in the art and enables rotation of the reel 11 while maintaining connection of the various described internal components of the rod 12 to the rotationally fixed umbilical cable 15. One simple example of the spoolable intervention rod is shown in FIG. 2. The rod 12 may consist of a fiber reinforced (e.g., carbon or glass fiber) plastic tube 12A in which may be embedded, for example, a steel conduit 12B. The conduit 12B may be used for movement of fluid, or may contain and protect optical fibers 12C and/or insulated electrical conductors. Other examples of the rod 12 may include more than one internal conduit and/or more or fewer electrical conductors and optical fibers.

Returning to FIG. 1, after the system 10 is coupled to the wellhead 14, a signal may be transmitted from the surface over the umbilical cable 15 to insert the rod 12 into the wellbore 16. Such insertion may be performed by operating the reel 11 to unspool the rod 12. Any wellbore intervention operation that may be performed at the end of the rod 12 in the wellbore may then be conducted by sending appropriate power and/or signals over the various devices (FIG. 2) in the rod 12. Alternatively, as explained with reference to FIG. IB, signals to cause the intervention operation to be performed may be communicated without using the umbilical cable, for example using acoustic transducers.

When the wellbore intervention operation is completed, to disconnect the seabed system 10, a command to stop the reel 11 (and/or withdraw the rod 12 as far as possible from the wellbore by operating the reel 11) may be communicated over the umbilical cable 15 (or remotely through the water as explained with reference to FIG. IB) and thereafter the wellbore may be secured by sealing against the rod 12. Sealing can be performed by one or several sealing mechanisms (FIG. 4) , wherein the commands to operate the sealing mechanisms are transmitted from the surface. For example, the wellhead 14 may have its own umbilical cable (not shown) extending to the surface or may be operated by acoustic telemetry in the water. Following successful withdrawal of the rod 12 from the wellbore 16, the umbilical cable 15 can be disconnected from the intervention system 10 using any known coupling device, whether remotely operable or by using a ROV, and withdrawn to the water surface. After the umbilical cable 15 and coupler (not shown) are pulled to the surface, the intervention system 10 can be left in place on the wellhead 14 as shown in FIG. 1.

In some examples, the intervention system may include an integral, battery operated monitoring and control system (NEED FIGURE) . Such monitoring and control system can be remotely operated and monitored from surface using standard communication links, for example, underwater acoustic telemetry. Using such a monitoring system, the wellbore owner or operator can send a command to the system to cut the rod and drop the rod into the well, if required in a particular situation.

FIG. 3 shows a well pressure safety system (including the blowout preventer - "BOP") 18 that may include a sealing mechanism such as an annular seal, and a rod cutting mechanism, such as shear rams . The pressure safety system is typically placed between the system 10 and the wellhead 14.

In some examples, the system may be used to deploy specific, selected intervention instruments into the wellbore without the need to disconnect the system from the wellhead. The particular intervention instruments may be selected at the time the intervention operation is started or planned. FIG. 4 shows an example of a Y- coupling 20 with a side entry sub 29 and a tool catcher 31 mounted between the wellhead 14 and the BOP system 18. The Y-coupling 20 and side entry sub 29 provide a sealable opening to insert one or more intervention tools into the wellbore while the intervention rod system remains attached to the wellhead 14. The Y-coupling preferably provides a smooth bend transition that has a radius of curvature at least as large as the minimum bend radius of a wellbore intervention tool (24A discussed below) . On the right hand of the bend in the side entry sub 29 as shown in FIG. 4, there may be disposed a valve 22 for pressure isolation and a coupling 23 for connecting and disconnecting one or more lubricator sections, e.g., 24, that can be lowered from a surface vessel (e.g., 2 in FIG. IA) and assembled to the side entry sub 29. Such assembly may be performed by ROV. Such lubricator 24 can be long joints of rigid conduit or can be spooled tubular such as coiled steel tubing. The lubricator 24 may also be short sections of tubular, depending on the length of the intervention tool to be deployed into the wellbore 14. An intervention tool 24A may be preassembled inside the lubricator 24. When the lubricator 24 is assembled to the side entry sub 29, the valve 23 may be opened and a pig 26, or well tractor, for example, may be used to move the tool 24A through the side entry sub 29 to the tool catcher 31 in the wellhead 14.

To insert the tool 24A into the wellbore 14, in one example, fluid is pumped in (at the right hand side) of the tool 24A. The fluid pressure will push the intervention tool 24A forward and into the wellbore 14, where the upper part of the intervention tool 24A will latch into the tool catcher 31. The intervention rod (12 in FIG. 1) may be latched to the upper part of the intervention tool 24A. Then the intervention tool 24A can be released from the tool catcher 31, (e.g., by breaking a shear pin disposed in the upper part of the intervention tool 24A. The rod 12 may be unspooled to move the intervention tool 24A to a selected depth in the wellbore. The intervention tool 24A may be operated to perform its particular function. The intervention tool 24A may be withdrawn from the wellbore by spooling the intervention rod 12 or the tool 24A may be left in the wellbore. If the intervention tool 24A is to be withdrawn from the wellbore, the upper part of the intervention tool 24A may be configured to latch in the tool catcher 31. The intervention rod 12 may then be disconnected from the upper part of the intervention tool 24A. The pig or tractor 26 may be once again coupled to the upper part of the intervention tool 24A to move the intervention tool 24A into the lubricator 24. Suitable shaping and/or diametric profiling of the upper part of the intervention tool 24A, the pig or tractor 26 and the Y-coupling 20 will facilitate the intervention tool 24A being returned to the lubricator 24. In one example, pumping fluid into the wellbore below the Y-coupling and bleeding off pressure on a valve used to pump the intervention tool 24A into the wellbore will transport the pig or tractor 26 out into the lubricator section (s) 24 again. Then the carbon fiber rod (12 in FIG. 1) can be be lowered in and connected to the uppermost part of the intervention tool 24A.

Short or long lubricator sections can be connected and disconnected from the coupling. FIG. 5 shows an example of a long lubricator section 28 which may include therein, for example, perforating guns 34 to complete a lengthy section of the wellbore (14 in FIG. 1) .

The upper part of the BOP system 18 is shown in more detail in FIG. 6 including parts intended to sealingly engage the intervention rod 12. The upper part of the BOP system may include an annular seal 50, which may include an inflatable annular elastomer seal or a bushing and grease injection line 51, similar to types used to seal armored electrical cable or slickline to a wellhead. A seal ram assembly 52 may be disposed below the annular seal, and may be engaged by actuation of hydraulic rams 52A having suitably shaped seal ram elements 52B to engage the outer surface of the intervention rod. In emergency cases, it may be necessary to cut the spoolable intervention rod to close the wellbore. For such cases the BOP system 18 may include "shear rams" 54, which also may be actuated by hydraulic rams 54A. Sealing, cutting elements 54B may be disposed at the inner ends of the rams 54A such that when the rams 54A are engaged they sever the rod and the sealing elements 54B seal the wellbore below.

FIG. 7 shows an example of battery powered, self contained system for operating the reel 11. The system shown in FIG. 7 may communicate signals through the water using a transducer 15C as explained with reference to FIG. IB. The control system may be enclosed in a suitable pressure proof housing 62. A battery 70 or similar energy storage device may provide electrical power to operate the various components of the system. The transducer 15C is in signal communication with a transceiver 66 that converts signals detected by the transducer into electrical signals readable by a central processor 68, which may be any microprocessor or microcontroller. The central processor 70 may detect commands transmitted from the vessel (2 in FIG. IB) , such as commands to extend or retract the rod 12 by operating the reel 11. A motor driver 64 may be in signal communication with the central processor 68 and provide electrical power to operate the motor 60 as instructed. The motor may be coaxially engaged with a collector (explained with reference to FIG. 1) so that power and signals communicated along the intervention rod 12 may be communicated, through a preamplifier 72 to the central processor 68. For example, signals received by one or more well logging sensors (not shown in FIG. 7) disposed at the end of the intervention rod 12 may be communicated to the central processor 68, formatted in the transceiver 66, and communicated to the vessel (2 in FIG. IB) using the transducer 15C.

The type of intervention tool is not in any way intended to limit the scope of the present invention and can include, without limitation, well logging tools, perforating guns, packers, clean out rods, inspection cameras, pumps, drills, mills and any other wellbore intervention tools known in the art. Such a subsea wellbore intervention system may have several advantages compared to others known in the art, for example: No riser is required to extend the well from the water bottom to the surface. Smaller intervention vessels can be used than for riser type systems. Higher severity weather operating windows, due to only having a umbilical to surface during operations may be operable Less load on the subsea wellhead due to lower rig-up height and weight, and less tension on wellhead system due to low sideways drag from water currents. Quick disconnect is possible in an emergency, and there is no need to cut the rod going into the wellbore in case of disconnect. Pump-down methodology built into the lower section of {e.g. composite) frame system for crown plug replacements in the wellhead, setting and retrieval of wellbore tools, perforating equipment, etc.

While the invention has been described with reference to a limited number of examples, those skilled in the art will appreciate that other implementations may be devised which do not depart from the scope of the present invention. Accordingly, the present invention shall be limited in scope only by the attached claims.

Claims

CLAIMSWhat is claimed is :

1. A subsea well intervention system, comprising: an intervention rod including at least one of a spoolable fiber reinforced plastic and an armored cable, the intervention rod disposed on a reel, the reel affixable to a structure proximate a subsea wellhead, the intervention rod configured having at least one of a conduit, an optical fiber and an electrical conductor therein; a seal device affixable to the subsea wellhead and configured to enable sealing travel therethrough of the intervention rod; and means for remotely operating the reel and seal device from a vessel on the surface of a body of water.

2. The system of claim 1 further comprising a tool catcher associated with the seal device, the tool catcher configured to transport an intervention tool from the vessel to the water bottom and to engage the subsea wellhead to enable passage of the intervention tool from the tool catcher to the interior of the wellbore.

3. The system of claim 1 wherein the seal device includes a cutting element configured to sever the intervention rod.

4. The system of claim 1 wherein the means for remotely operating comprises at least one of an electrical and hydraulic umbilical line extending from the vessel to the reel and seal device.

5. The system of claim 1 wherein the means for remotely operating comprises a transceiver acoustically coupled to a body of water.

6. The system of claim 5 further comprising a battery and a central processor operatively associated with the reel and disposed proximate thereto, the central processor in signal communication with the transceiver and with a motor operatively coupled to the reel, the processor configured to decode operating commands transmitted from the water surface and to transmit to the water surface signals representative of measurements made by at least one sensor associated with the rod.

7. The system of claim 1 wherein the rod comprises at least one of glass fiber, carbon fiber and graphite fiber.

8. The system of claim 3 further comprising a motive element disposed in the tool catcher, the motive element configured to move a tool coupled thereto under fluid pressure applied to an end of the tool catcher.

9. A method for conducting intervention operations in a wellbore having a subsea wellhead, comprising: affixing a reel having a spoolable intervention rod comprising at least one of a fiber reinforced plastic rod and an armored cable wound thereon proximate the subsea wellhead; affixing a sealing element onto the wellhead, the sealing element enabling sealing passage of the intervention rod therethrough into the wellbore; sending a command from proximate the surface of a body of water to operate the reel to extend the intervention rod into the wellbore; and conducting at least one wellbore intervention operation proximate the end of the rod.

10. The method of claim 9 further comprising sending a command from proximate the surface to retract the intervention rod from the wellbore.

11.. The method of claim 10 further comprising inserting an intervention tool into an upper part of the wellbore from a side entry sub; affixing the end of the rod to an upper end of the intervention tool and lowering the intervention tool into the wellbore.

12. The method of claim 11 further comprising releasing the intervention tool from the upper part of the wellbore prior to insertion into the wellbore.

13. The method of claim 12 further comprising making at least one parameter measurement using the intervention instrument and transmitting the measurement to proximate the water surface.