Dual-Walled Coiled Tubing Deployed Pump
Dual-walled coiled tubing assemblies are used to dispose an electric device, such as an electric submersible pump into a wellbore. Dual-walled coiled tubing assemblies include an inner coiled tubing string and an outer coiled tubing string as well as a power cable.
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1. Field of the Invention
The invention relates generally to the use of strings of coiled tubing to dispose devices, such as electrical submersible pumps into a wellbore.
2. Description of the Related Art
Electric submersible pumps (ESPs) are used to pump hydrocarbon fluids and/or water from subterranean locations. ESPs require electrical power to be supplied to them from surface. A typical ESP assembly includes a centrifugal pump that is mounted to an electrical motor. A power cable extends from the surface to the motor of the ESP assembly. Conventionally, when ESPs are run into a wellbore, the power cable is strapped to the outer surface of production tubing sections.
SUMMARY OF THE INVENTIONThe invention provides systems and methods for disposing an ESP, or similar device, into a wellbore using running arrangements which incorporate inner and outer coiled tubing strings as well as a power cable which provides power to the motor of the ESP. In a first described embodiment, a power cable is disposed radially between inner and outer coiled tubing strings. In a second described embodiment, a power cable is disposed within the inner coiled tubing string. These running arrangements provide flow paths which allow for the flow of produced fluids. In certain embodiments, two flow paths are provided.
The use of dual-walled coiled tubing string running assemblies provides the possibility of injecting an ESP into a live well which has pressure at surface. Depending upon the corrosiveness of the wellbore environment and the cable location (i.e., within the inner coiled tubing string or between the inner and outer coiled tubing strings), tubing of different grades, including Cr16, could be used. With the proper selection of coiled tubing and ESP components, arrangements constructed in accordance with the present invention provide the potential to run an ESP assembly deeper into a well than conventional technologies permit.
Production arrangements are described which use dual-walled coiled tubing run ESPs to produce hydrocarbon production fluids from wellbores. Embodiments are described wherein capillary lines are located within the dual-walled coiled tubing assembly. The invention encompasses dual-walled coiled tubing assemblies that are used to dispose an electric device (such as an ESP) into a wellbore. Additionally, the invention encompasses hydrocarbon production assemblies that include an ESP as well as a dual-walled coiled tubing assembly that is used to dispose the ESP into a wellbore.
The advantages and further aspects of the invention will be readily appreciated by those of ordinary skill in the art as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference characters designate like or similar elements throughout the several figures of the drawing and wherein:
The term “dual-walled,” as used herein, is intended to refer broadly to arrangements wherein an inner tubular string or member is located radially within an outer tubular string or member to provide a dual-walled tubing structure. A structure can be dual-walled without regard to whether the inner and outer tubular strings are coaxial or concentric.
In the arrangement shown in
According to a second exemplary arrangement, which is depicted in
A power cable 40 is disposed radially between the inner and outer coiled tubing strings 32 and 34. The depicted power cable 40 has three electrical conductors 42 contained within an insulating sheath 44. The power cable 40 may contain other elements, such as a gas barrier, a jacket or armor, as generally known in the art. Although three power conductors 42 are depicted and are typical, there may be more or fewer than three depending upon the requirements for downhole power and control. Referring to
Flexible straps 46 are used to secure the cable 40 to the inner coiled tubing string 32. The term “strap” is used here to denote any form of tensile or compressive fastener, such as a cable, rope, tie, binder, clamp and the like. The straps 46 may be secured about the cable 40 and inner coiled tubing string 32 by tightening, tying, latching, bolting or in other ways known in the art. The straps 46 enclose both the cable 40 and inner coiled tubing string 32. When the dual-walled coiled tubing assembly 30 is assembled, an axial fluid flowpath 48 is defined within the outer coiled tubing string 34. In the depicted assembly 30, the central axial passage 36 provides a first axial fluid flowpath while the axial fluid flowpath 48 serves a second axial fluid flowpath. The presence of two, separate axial fluid flowpaths within a single assembly 30 provides the advantage of allowing two separate streams of fluid to be transmitted along the assembly 30. Fluids might be transmitted uphole as a result of the ESP pump 26 or transmitted downhole in instances wherein one of the flow paths is being used to inject specialized fluids, which might include scale or asphaltene inhibitors.
It is noted that the inner coiled tubing string 32 is shown as offset from the center of the outer coiled tubing string 34 due to the presence of the cable 40. As illustrated in
The dual-walled coiled tubing assembly 30 may be assembled by first disposing the cable 40 in parallel contact with the inner coiled tubing string 32 and then affixing the cable 40 to the inner coiled tubing string 32 with straps 42. Preferably, the straps 42 are used to affix the cable 40 to the inner coiled tubing string 32 in appropriate spaced intervals which are sufficient to affix the cable 40 to the inner coiled tubing string 32 without permitting a large degree of sagging of the cable 40 and to ensure that the cable weight is held uniformly by the inner coiled tubing string 32 in order to prevent breakage of the cable 40. Thereafter, the inner coiled tubing string 32 and affixed cable 40 are disposed into the outer coiled tubing string 34. This may be done vertically while the outer coiled tubing string 34 is hanging in a well. Alternatively, it may be done horizontally with the outer coiled tubing string 34 stretched out and with the inner coiled tubing string 32 and affixed cable 40 either pushed or pulled into the outer coiled tubing string 34. Metal-to-metal lubricants can be used to reduce the contact friction and ease the installation. More typically, the cable 40 can be fastened to the inner coiled tubing string 32 as the inner coiled tubing string 32 is disposed into the outer coiled tubing string 34. As the cable 40 is affixed to the inner coiled tubing string 32, both are disposed into the outer coiled tubing string 34. This may be done vertically as the outer coiled tubing string 34 is hanging in a well. Alternatively, it may be done horizontally with the outer coiled tubing string 34 stretched out and with the inner coiled tubing string 32 either pushed or pulled into the outer coiled tubing string 34, taking the cable 40 along with it. Again, metal-to-metal lubricants can be used to reduce the contact friction and ease installation.
An assembled dual-walled coiled tubing assembly 30 can be wound onto a coiled tubing reel of a type known in the art for retaining spools of coiled tubing and transported to a well site for use. An ESP assembly, such as ESP assembly 20 is then affixed to the coiled tubing assembly 30 and run into the wellbore in conventional fashion.
A further method of injecting cable through a coiled tubing string would be to use a water-based metal-on-metal lubricant with a low coefficient of friction, such as EasyReach™ lubricant, that will permit longer lengths of cables and coiled tubing strings to be disposed within surrounding coiled tubing strings. Modeling of these lengths could be performed taking into account coiled tubing sizes and cable sizes and using suitable software designed for design and planning for coiled tubing operations.
The dual-walled coiled tubing assembly 50 may be assembled by first disposing the cable 40′ into the central axial passage 36 of the inner coiled tubing string 32. This may be done vertically by lowering the cable 40′ into the inner coiled tubing string 32 while it is hanging vertically in a well. Alternatively, it may be done horizontally with the inner coiled tubing string 32 stretched out and with the cable 40′ pulled into the inner coiled tubing string 32. Once more, metal-to-metal lubricants can be used to reduce the contact friction and ease installation. The cable 40′ may also be placed into the inner coiled tubing string 32 while the inner coiled tubing string 32 is being manufactured. The inner coiled tubing string 32 and cable 40′ are then inserted into the outer coiled tubing string 34. These two previous steps may be reversed. An assembled dual-walled coiled tubing assembly 50 can be wound onto a coiled tubing reel of a type known in the art for retaining spools of coiled tubing and transported to a well site for use. An ESP assembly, such as ESP assembly 20 is then affixed to the coiled tubing assembly 50 and run into the wellbore 10.
The inventors believe that dual-walled coiled tubing assemblies constructed in accordance with the present invention are advantageous for running ESPs into wellbores. The cable 40 is protected from damage since it is contained within the protection of the outer coiled tubing string 34. Such damage has been known to occur as a result of wellbore debris or disposal of the cable through deviated or horizontal wellbore portions. In some constructions, dual fluid flowpaths are available for flow of fluid along the assembly. Additionally, disposing the cable within the outer coiled tubing string 34 permits a standard packer to be set in the wellbore without the need for a specialized arrangement having a bypass to allow a separate cable to be disposed through the packer. The various fluid flowpaths provided by the dual-walled coiled tubing assemblies (i.e., 30, 50) of the present invention might also provide one or more pressurized paths for use in downhole activation schemes in which a port is opened or closed or a tool, such as a packer is activated.
An arrangement which the inventors believe would be desirable for certain production situations would be an arrangement similar to that depicted in
The use of dual-walled coiled tubing assemblies, such as assemblies 30, 50 described herein, provide the possibility of injecting an ESP assembly 20 into a live wellbore 10 which is under pressure from surface 14. Because the power cable 40140′140a is contained within the outer coiled tubing string 34, it is mechanically protected from damage due to friction or abrasion with a surrounding casing or other objects or surfaces during run-in. ESPs run on standard coiled tubing or on regular tubing, where the power cable is strapped to the outside of the tubing, the ESP assembly cannot normally be run into live wells since there is currently not an effective way to seal around the tubing and cable during running in. Therefore, the pressure at surface cannot be contained. In order to run into a live wellbore, in one embodiment, the system would be sealed into a downhole packer and fluid produced up the dual-walled coiled tubing assembly.
Depending upon the corrosiveness of the wellbore environment into which the ESP 20 will be run, and the location of the power cable 40 or 40′140a, coiled tubing of different grades, including Cr16 grade stainless steel, could be used. For example, depending upon downhole conditions, the inner and outer coiled tubing strings 32, 34 may be made of different grades of steel, thereby maximizing their resistance to corrosion.
The foregoing description is directed to particular embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to one skilled in the art that many modifications and changes to the embodiment set forth above are possible without departing from the scope and the spirit of the invention.
Claims
1. A dual-walled coiled tubing assembly to dispose an electric submersible pump into a wellbore, the dual-walled coiled tubing assembly comprising:
- an inner coiled tubing string defining an inner coiled tubing central axial pathway along its length;
- an outer coiled tubing string radially surrounding the inner coiled tubing string, the outer coiled tubing string defining an outer coiled tubing string central axial passage along its length; and
- a power cable to provide electric power to the electric device, the power cable being disposed within the outer coiled tubing string central axial passage.
2. The dual-walled coiled tubing assembly of claim 1 wherein the power cable is further disposed within the inner coiled tubing central axial passageway.
3. The dual-walled coiled tubing assembly of claim 1 wherein the power cable is disposed radially between the inner coiled tubing string and the outer coiled tubing string.
4. The dual-walled coiled tubing assembly of claim 1 further comprising one or more capillary lines disposed within the outer coiled tubing string.
5. The dual-walled coiled tubing assembly of claim 4 wherein the one or more capillary lines is/are located radially between the inner coiled tubing string and the outer coiled tubing string.
6. The dual-walled coiled tubing assembly of claim 4 wherein the one or more capillary lines is/are located radially within the inner coiled tubing string.
7. The dual-walled coiled tubing assembly of claim 4 wherein the one or more capillary lines is/are located within the power cable.
8. The dual-walled coiled tubing assembly of claim 1 further comprising separate first and second fluid flow paths defined within the outer coiled tubing string.
9. The dual-walled coiled tubing assembly of claim 1 further comprising at least one strap securing the power cable to the inner coiled tubing string.
10. The dual-walled coiled tubing assembly of claim 1 wherein the electric submersible pump assembly includes a pump section and a motor section.
11. The dual-walled coiled tubing assembly of claim 1 wherein the power cable presents an axial cross-section having:
- a first side surface that is concave and shaped to be generally complementary to an outer radial surface of the inner coiled tubing string; and
- a second side surface that is convex and shaped to be generally complementary to an inner radial surface of the outer coiled tubing string.
12. A hydrocarbon production assembly to produce hydrocarbon fluid from a wellbore, the production assembly comprising:
- an electric submersible pump;
- a dual-walled coiled tubing assembly to dispose the electric submersible pump into the wellbore, the dual-walled coiled tubing assembly comprising:
- an inner coiled tubing string defining an inner coiled tubing central axial pathway along its length;
- an outer coiled tubing string radially surrounding the inner coiled tubing string, the outer coiled tubing string defining an outer coiled tubing string central axial passage along its length; and
- a power cable to provide electric power to the electric submersible pump, the power cable being disposed within the outer coiled tubing string central axial passage.
13. The hydrocarbon production assembly of claim 12 wherein the power cable is further disposed within the inner coiled tubing central axial passageway.
14. The hydrocarbon production assembly of claim 12 wherein the power cable is disposed radially between the inner coiled tubing string and the outer coiled tubing string.
15. The hydrocarbon production assembly of claim 12 further comprising one or more capillary lines disposed within the outer coiled tubing string.
16. The hydrocarbon production assembly of claim 15 wherein the one or more capillary lines is/are located radially between the inner coiled tubing string and the outer coiled tubing string.
17. The hydrocarbon production assembly of claim 15 wherein the one or more capillary lines is/are located within the power cable.
18. The hydrocarbon production assembly of claim 12 further comprising separate first and second fluid flowpaths defined within the outer coiled tubing string.
19. The hydrocarbon production assembly of claim 12 further comprising at least one strap securing the power cable to the inner coiled tubing string.
20. The hydrocarbon production assembly of claim 12 wherein the power cable presents an axial cross-section having:
- a first side surface that is concave and shaped to be generally complementary to an outer radial surface of the inner coiled tubing string; and
- a second side surface that is convex and shaped to be generally complementary to an inner radial surface of the outer coiled tubing string.
21. The hydrocarbon production assembly of claim 12 further comprising a packer forming a seal between the dual-walled coiled tubing assembly and the wellbore and wherein:
- an annulus is defined between the dual-walled coiled tubing assembly and the wellbore; and
- production fluid is flowed through the annulus.
22. The hydrocarbon production assembly of claim 12 further comprising a packer forming a seal between the dual-walled coiled tubing assembly and the wellbore and wherein:
- an annulus is defined between the dual-walled coiled tubing assembly and the wellbore; and
- production fluid is flowed through the dual-walled coiled tubing assembly.
23. The hydrocarbon production assembly of claim 12 further comprising a packer forming a seal between the dual-walled coiled tubing assembly and the wellbore and wherein:
- an annulus is defined between the dual-walled coiled tubing assembly and the wellbore; and
- production fluid is flowed through the annulus and the dual-walled coiled tubing assembly.
24. The dual-walled coiled tubing assembly of claim 12 further comprising separate first and second fluid injection paths defined within the outer coiled tubing string.
25. The dual-walled coiled tubing assembly of claim 12 wherein at least one of the inner and outer coiled tubing strings are formed of corrosion-resistant material and one of the inner and outer coiled tubing strings is composed of a grade of metal that is different from that of the other of the inner and outer coiled tubing strings.
26. The dual-walled coiled tubing assembly of claim 12 wherein a metal-to-metal lubricant is used during manufacture of the dual-walled coiled tubing assembly.
Type: Application
Filed: Mar 2, 2015
Publication Date: Sep 8, 2016
Applicant: Baker Hughes Incorporated (Houston, TX)
Inventors: Andre J. Naumann (Calgary), Silviu Livescu (Calgary)
Application Number: 14/635,569