Coiled tubing

Abstract

A length of tubing and related apparatus and methods are described, where the length of tubing is deployable from a coiled configuration to an uncoiled configuration for performing a coiled tubing operation in a wellbore. The length of tubing includes a pipe of metal, and a liner of composite material that lines the pipe. The liner or the lined pipe includes a wall structure that incorporates means to communicate at least one service along the tubing.

Claims

1. A method of producing a length of tubing to be used as a coiled tubing in a wellbore, the method comprising: providing a pipe of metal to be used as an outer pipe having an outer surface and an inner surface; providing at least one elongate member to communicate or deliver at least one service along the coiled tubing in use; producing a liner for insertion into and lining an inside of the outer pipe, the liner having an outer surface and an inner surface, the liner being configured to provide, when inserted into the outer pipe, a clearance between the outer surface of the liner and the inner surface of the outer pipe, wherein the liner is formed as a composite material having fibers combined with a polymer by a pultrusion, filament winding, or pull-winding process, wherein the pultrusion, filament winding, or pull-winding process to form the liner comprises the steps of: forming a wall structure of the liner of composite material; winding the at least one elongate member together with fiber threads or filaments; incorporating the elongate member into the wall structure; and guiding the at least one elongate member into the wall structure of the liner after an inner portion of the wall structure is formed and before an outer portion of the wall structure is formed; retrofit inserting the produced liner of composite material into the outer pipe to line the inside of the outer pipe with the liner of composite material having the at least one elongate member incorporated therein; wherein the liner is inserted into the outer pipe by one end of the liner having a closure member and by applying pressure inside the liner to drive the liner into the outer pipe; and wherein the outer surface of the liner inserted into the outer pipe is in friction contact with the inner surface of the outer pipe.

2. The method of claim 1, wherein the at least one elongate member for communicating or delivering the service along the tubing and which is guided into the wall structure comprises an electrical conductor, an optical fiber, or a fluid channel.

3. A length of coiled tubing for performing a coiled tubing operation in a wellbore, the coiled tubing comprising: an outer pipe of metal having an outer surface and an inner surface; at least one elongate member for communicating or delivering at least one service along the coiled tubing; and a liner for insertion into and lining an inside of the outer pipe and having an outer surface and an inner surface, the liner is configured to provide, when inserted into the outer pipe, a clearance between the outer surface of the liner and the inner surface of the outer pipe, wherein the liner is formed as a composite material having fibers combined with a polymer via a pultrusion, filament winding, or pull-winding process, and wherein the liner is configured to include the at least one elongate member incorporated therein; wherein the liner having the at least one elongate member incorporated therein includes a wall structure having the at least one elongate member wound together with fiber threads or filaments and guided into the wall structure of the liner after an inner portion of the wall structure is formed and before an outer portion of the wall structure is formed.

4. The length of coiled tubing of claim 3, wherein the at least one elongate member for communicating or delivering at least one service along the coiled tubing includes at least one of an electrical conductor, optical fiber, and fluid channel.

5. The length of coiled tubing of claim 4, wherein the at least one service along the coiled tubing includes at least one of electric power, data, and control fluid.

6. The length of coiled tubing of claim 3, wherein the at least one elongate member includes a plurality of electrical conductors, optical fibers, or a combination thereof, and wherein the electrical conductors or optical fibers extend axially in parallel along the outer pipe.

7. The length of coiled tubing of claim 6, wherein the outer surface of the liner includes a plurality of radially protruding ribs that are parallel to one another and each is in friction contact with the inner surface of the outer pipe.

8. The length of coiled tubing of claim 7, wherein each of the plurality of radially protruding ribs includes respective one of the electrical conductors or optical fibers.

9. The length of coiled tubing of claim 8, wherein the plurality of ribs is produced using a die or a mold during the pull-winding process.

10. The length of coiled tubing of claim 3, wherein the composite material of the liner is a combination of a thermoplastic polymer and fibers, and wherein the thermoplastic polymer is selected from the group consisting of a polyether ether ketone (PEEK), polyphenylene sulfide (PPS), perfluoroalkoxy (PFA), and polyvinylidene fluoride (PVDF).

11. A method of performing a coiled tubing operation in a wellbore, the method comprising: providing a length of coiled tubing; supporting a tool on an end of the coiled tubing; uncoiling the coiled tubing from a drum into a well to deploy the tool in the wellbore; using the tool to perform an operation, wherein the coiled tubing comprising: an outer pipe of metal having an outer surface and an inner surface; at least one elongate member for communicating or delivering at least one service along the coiled tubing; and a liner inserted into and lining an inside of the outer pipe and having an outer surface and an inner surface, the liner providing a clearance between the outer surface of the liner and the inner surface of the outer pipe, wherein the liner is formed as a composite material having fibers combined with a polymer via a pultrusion, filament winding, or pull-winding process, and wherein the liner includes the at least one elongate member incorporated therein; wherein the liner having the at least one elongate member incorporated therein is produced by forming a wall structure of the liner, winding the at least one elongate member together with fiber threads or filaments, incorporating the at least one elongate member into the wall structure, and guiding the at least one elongate member into the wall structure of the liner after an inner portion of the wall structure is formed and before an outer portion of the wall structure is formed; transmitting a work fluid through a central bore of the tubing and into the well for treating the wellbore; and communicating power, data or signals along the coiled tubing through the at least one elongate member incorporated in the wall structure of the liner.

12. The method of claim 11, wherein the performed operation comprises a well workover or well intervention operation.

13. The method of claim 11 further comprises transmitting a work fluid through a bore of the tubing and into the well for treating the wellbore.

14. The method of claim 13, wherein the work fluid comprises one or more proppants or chemicals.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There will now be described, by way of example only, embodiments of the invention, with reference to the accompanying drawings, in which:

(2) FIG. 1 is a perspective sectional view of a length of tubing according to an embodiment of the invention;

(3) FIG. 2 is a perspective view of a liner for a length of tubing according to an embodiment of the invention;

(4) FIG. 3 is a sectional view of the length of tubing perpendicular to the longitudinal direction according to an embodiment of the invention;

(5) FIG. 4 is a schematic representation of a step of a method of producing the tubing; and

(6) FIG. 5 is a schematic representation of performing an operation in the wellbore using the tubing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) The length of tubing 1 in FIG. 1 has an outer pipe 3 of steel and an inner liner pipe 4 of composite material incorporating means in the form of elongate electrical conductors 7 for communicating power, data or signals along the tubing.

(8) The tubing 1 has a central longitudinal axis 21. The electrical conductors 7 extend axially in parallel along the tubing 1. The electrical conductors are each associated with a radially protruding rib 8. The ribs 8 are in friction contact against an inside of the outer pipe 3. The liner pipe 4 is inserted into the outer pipe 3 in order to line the pipe to produce the lined tubing. The ribs 8 act to provide stand off from the inner surface of the pipe 3 so as to facilitate reduction of friction and provide space for escape of air upon inserting the liner into place.

(9) In use, coiled tubing comprising the length of tubing of FIG. 1 can be employed in a wellbore with a tool on a far end of the tubing to perform an operation in the wellbore. The length of tubing is flexible and is deployed from coiled configuration on the reel to an uncoiled configuration where it is used in the wellbore. A work fluid for performing the operation can be transmitted through the bore 9 of the tubing 1 into the wellbore. Example work fluids include proppants or chemicals e.g., for treating the wellbore or formation.

(10) In FIG. 2, an alternative liner pipe 4 is illustrated. The liner pipe of FIG. 2 can be fitted similarly to an outer pipe 3. In this case however, the liner pipe 4 has communication members in the form of three optical fibers 17 for data transmission along the tubing and three electrical conductors 7 for transmitting electrical power along the tubing. The ribs 8 are wider and fewer than in FIG. 1.

(11) In FIG. 3, an alternative tubing 1 is depicted. The liner pipe 4 in this example does not have ribs, but the liner pipe is dimensioned relative to the outer pipe 3 to provide clearance 14 between the outer surface of the liner pipe 4 and the inner surface of the outer pipe 3, sufficient to allow insertion without succumbing to friction effects. Three conductors 7 are provided and incorporated into the material of the liner pipe.

(12) The liner pipe 4 can be inserted into the outer pipe 3 as indicated in FIG. 4. An end of the liner pipe 4 is closed off by closure member 33. The liner pipe, closed end first, is inserted into the outer pipe 3. The interior 36 of the inner pipe is pressurized by delivering a pressurized fluid through inlet 37 at the opposite end. The pressure in the interior 36 acts against a surface of the closure member and drives the liner pipe 4 into the outer pipe to thereby form the lined tubing 1.

(13) In use, apparatus 100 is generally depicted where coiled tubing 1 is uncoiled from a reel 105 that is located topsides at surface 106, e.g., a rig. The tubing 1 is being used in a wellbore 109 for performing a downhole operation in the wellbore. Sensors (not shown) are provided on the coiled tubing 1 in the wellbore. Data from the sensors are communicated up through the coiled tubing 1 to surface through the communication means, e.g., conductor or optical fiber, in the material of the wall structure of the liner pipe of the tubing. Thus, data can be obtained during wellbore operations. Work fluid can be transmitted through the interior of the tubing 1 and delivered into the wellbore in the wellbore operation as indicated by arrow W.

(14) Operational temperatures in the well are typically up to 150 to 170 degrees Celsius. The coiled tubing is subjected to tough chemical conditions. Materials are selected and the coiled tubing constructed accordingly. The outer pipe is in this case is a flexible pipe of steel.

(15) The composite material of the liner is a combination of polymer and fibers, and the polymer can be for instance a thermoplastic polymer such as one of polyetheretherketone PEEK, polyethylene sulphide PPS, and perfluoroalkoxy PFA. PVDF is an alternative for lower temperatures below 140 degrees Celsius. PEEK can be advantageous in the well in that it has low water absorption, and can cope well with chemicals such as ammonia gas, carbon monoxide gas, ethylene glycol (50%), hydrogen sulphide gas, methane, phosphoric acid (50%), sodium hydroxide solution, and sulphur dioxide gas. PPS can be advantageous in that it can have very high resistance to thermal degradation and chemical reactivity and low moisture absorption under high heat and humidity conditions. It can cope well with methane, carbon dioxide, hydrogen sulphide, hydrogen gas, nitrogen, potassium chloride, sulphur dioxide, salt water/seawater. PFA resins may be advantageous in good chemical and thermal stability.

(16) The composite fibers can be selected suitably for reinforcement of the tube for facilitating circumferential, axial and radial strength to withstand high operating pressures and tensile and compression stresses. The fibers can be provided in fiber reinforced UD tapes with carbon or glass fibers. The form of fiber reinforcement can be decided as appropriate for the processing technique for producing the tubing.

(17) The liner pipe of composite material can suitably be produced by pull winding. The conductors, e.g., wires, are incorporated in the wall of the liner pipe by appropriate placement of the conductor in the course of the manufacturing process. A monitored process is employed, where the wire/conductor is guided into the center of the wall at the appropriate stage, e.g., after an inner portion of the wall has been formed and before an outer portion of the wall is formed. Visible light and/or x-ray illumination of the liner pipe under manufacture is used to control the process and ensure proper placement of the conductor, preferably embedded centrally in the wall material of the composite liner pipe. The conductor can be positioned in desired position within a tolerance in the range of 0.3 mm to 0.5 mm. The ribs 8 of the external structure of the tubing are produced by the die and/or mold in the pull winding process. The die/mold gives the desired design, shape and structure which can be predefined as required.

(18) The technique can provide significant benefits as data can be collected and retrieved in real time and throughout operations being carried out in the wellbore. The provision of the communication member in the material of the wall of the tubing can provide a robust positioning for the communication member, where it may not be susceptible to the effects of work fluid transmitted through the tubing. Thus, risks of damage, wear, and pauses in operations can be avoided or reduced. Provision of the liner, in effect in the form of a flexible sock that can be readily inserted and retrofitted to metal coiled tubing pipes. The outer pipe of steel can in itself be comparable in performance of flexure, strength, integrity etc. to traditional steel coiled tubing, although the performance is enhanced in the present concept by the provision in addition of the liner pipe.

(19) Various modifications and improvements may be made without departing from the scope of the invention herein described. For example, in some variants an electrical conductor may instead be an optical fiber for data communication and/or sensing conditions in the tubing. A fluid conduit may be provided in place of an electrical conductor for conveying control fluid along the tubing e.g., for controlling a downhole valve or the like.

(20) Changes and modifications in the specifically-described embodiments may be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims as interpreted according to the principles of patent law including the doctrine of equivalents.