GB2296367A - Fluid line with integral electrical conductor - Google Patents

Abstract

A tube 10 e.g of stainless steel or plastics, surrounds at least one conductor 14 which is held by a spacer 12 e.g. of PTFE. The voids 18, 20, 22 between the radial projections 16 of the spacer and the tube's inside wall can be used as flow channels for the transmission of fluid pressure to a remote location, such as downhole; or can be filled with a sealing material (24 Figure 1) e.g. epoxy. The conductors are protected because they are kept away from the tubing wall and by the sealing material. <IMAGE>

Description

FLUID LINE WITH INTEGRAL ELECIRIC:AL CONDUCTOR The field of this invention reiates to control lines which can transmit fluids to remote locations and more panicuiarly, control lines which can be used in oil and gas operations, such as subsea. wherein it is also advantageous to transmit electrical signals to a remote point.

In many applications in the oil and gas industry it is desirable to transmit fluid pressure to a remote location for actuation of equipment, as well as to run electrical conductors for either transmission of signals or power to or from the surface to a subsurface location or for other reasons. Typically, a conduit, which, if small and sufficiently flexible, can be unrolled from a roll, is run alongside the production tubing or otherwise into a borehole.If signals are to be sent from the wcilbore to the surface electrically, a separate cable has been used, which many times is bundled to the exterior of the control tubing such that the hydraulic signals pass through the control tubing while the electrical, generally low-voltage signals, which record any number of downhole well conditions or operate low-voltage equipment, use the adjacent cable for transmission of such signals. It has also been attempted in the past to run the electrical signal cable into and through a coiled tubing unit. In those instances. the signal cable is externally shielded to prevent any signal interference from the surrounding tubing structure.One of the problems in this type of installation has been that the shielded cable would develop flaws or pinholes in its outer protective casing, which would then allow the fluids to migrate into the cable, damaging the signal conductors therein. Additionally, another problem encountered with such designs is that the conductor cable running through the tubing could in many places orient itself adjacent the tubing wall, particularly if the well was in any way deviated. The contact between the electrical cable and the tubing wall could cause two problems. First, it could cause abrasion of the shield material against the inside surface of the tubing wall, which ultimately would result in compromising the integrity of the covering for the conductors. This, as previously described, could cause a breakdown in the ability to transmit signals through the conductors.Additionally, close proximity to the tubing wall also rendered the internal cable vulnerable to damage from mechanical impacts on the tubing in situations where the cable is located up against the inside tubing wall.

Such impacts could cause dents in the tubing wall, which would translate directly to the cable, damaging and perhaps severing the cable. Finally, and to a lesser extent, close proximity to the inside wall of the tubing also created some potential risk of signal interference from the metallic tubing wall.

Space is routinely at a premium in oil and gas installations, particularly in offshore applications. It is frequently desirable that the external control tubing have as small a diameter as possible, while, at the same time, it must have the necessary rigidity and internal diameter to allow accommodation of an internal conductor. What is desirable and heretofore lacking in the known equipment is a compact design where a conductor can be effectively isolated and located reasonably centrally to the tubing to minimize damage to the cable from impacts to the tubing.Additionally, with the conductors positioned within the tubing and their position retained away from the tubing wall, the spaces around the conductor can be used to allow fluid flow or, in the alternative, can be filled with a sealing material which provides further durability to the assembly of conductors, insulators/centralizers, and void sealant, all disposed within the tubing.

SUMMARY OF TE INVENTION Conductors are placed in an insulator which acts as a spacer/centralizer for the conductors, which are in turn mounted within tubing. The void spaces between the insulator and the tubing inside wall can be filled with a sealing material.

Alternatively, the voids around the substantially centralized conductors can be used as flow channels for the transmission of fluid pressure to a remote location, such as downhole. The conductors are protected because they are kept away from the tubing wall and can be further protected by the addition of the sealing material.

DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view of the tubing showing the conductor therein with a filling in between.

Figure 2 is the view of Figure 1 without the filling.

Figure 3 is the view of Figure 2, with a schematic representation of a combination of a hydraulic and electrical element showing a typical application of the apparatus of the present invention.

Figure 1 illustrates the apparatus A of the present invention. It comprises an external housing or tube 10 which can be made in a variety of corosion-resis- tant materials, including metals such as 316 Stainless Steel, Inconel, as well as rigid plastic materials. Inside the housing 10 is a spacer 12. Inside the spacer 12 is conductor or conductors 14. Conductors 14 can be one or more strands which collectively can transmit a signal or signals. A strand or groups of strands can be separately bundled and shielded before bering mounted to the spacer 12. In this manner, the tubing 10 carries a plurality of potential signal or power transmission avenues within the same spacer 12.In the preferred embodiment, the spacer 12 has a plurality of radial projections 16, which are spaced at 1200 intervals and which extend radially from a hub 17, to create three parallel flowpaths 18, 20, and 22.

The flowpaths can be used as such or can in the alternative, as shown in Figure 1, be filled with an epoxy 24. By adding the epoxy 24, additional protection for the conductors 14 is provided. The radially extending members 16 also help to centralize the conductors 14 and keep them away from the outer housing 10. By centralizing the conductors 14, they are less prone to be damaged. Furthermore, the control signals passing therethrough are less likely to suffer interference from adjacent metal components, such as housing 10. When the assembly is put together, as shown in Figure 1, with the flowpaths 18, 20, and 22 further filled with epoxy, the assembly becomes more durable in withstanding mechanical shocks but yet remains sufficiently flexible to allow coiling of the housing 10 onto a roll (not shown) for easy storage and dispensing when needed. While the preferred embodiment indicates the conductors to be centralized, an offset location, but removed from the housing or tubing 10, is still within the purview of the invention. While three radial extensions 16 are shown in the preferred embodiment, different configurations can be employed to accomplish the positioning ftature of getting the conductors 14 away from the tubing wall 10. For example, fewer or greater number of radially extending fins, such as 16, can be used. Different geometric shapes that extend from a hub that encircles the conductors 14 can be used, such as a single helix or a multiple helix, as long as their spacing is not so great or radial extension too small so as to allow the hub that surrounds the conductors to engage the inner wall of the housing or tubing 10.The conductors 14 can be further wrapped with a signal-insulating material prior to being inserted into the spacer 12.

In the preferred embodiment, the spacer assembly 12 is extruded onto the conductors 14 while the tubing, which originally comes in a flat sheet, is rolled into a tubing form and the seam is welded around the spacer 12. The assembly is oriented so that the seam which forms the tubing 10 is not aligned with any one of the radially extending members 16 to avoid any damage to them during the welding or brazing process. In this manner, a continuous-length segment of the apparatus A can be assembled and rolled onto a reel as it is put together.

Figure 3 illustrates the application of the apparatus A in a schematic manner to allow for operation of a hydraulically actuated component, as well as at least one electrically actuated component. The hydraulically actuated component is schematically illustrated as a valve 26 but could in an actual application could be any one of a number of different components. The electrical segment is illustrated as box 28. In a particular application, the hydraulically actuated component can be a downhole valve which is operated by a shifting sleeve or some other hydraulically actuated operator and the box 28 can be a sensor or sensors which can respond to indicate whether a shaft has turned, or a sleeve has shifted, or the like. Separate signal-carrying capacity can be provided within hub 17 if conductors are separately bundled and insulated as a group prior to having hub 17 extruded over them.In this way, multiple signal or error transmission functions can be simultaneously serviced.

Many potential applications are possible for the apparatus A of the present invention. For example, the apparatus A can be used to operate a solenoidoperated safety valve with hydraulic communication capability for an insert valve.

The apparatus A can also be used for proximity indicators or position sensors to indicate if a valve is full open or full closed. An electrically operated mechanism to lock a flapper on a subsurface safety valve in the open position can operated with the apparatus A of the present invention.Other applications include: (1) downhole control line pump and reservoir to eliminate hydrostatic head on deep set valves, (2) a solenoid to operate the flapper on a subsurface safety valve without stroking the flow tube, (3) an electrical assist mechanism for stuck flow tubes, (4) electrical communication for wireline tools, (5) electrical/hydraulic shuttle valve operation for ultra deep set applications, (6) electrically operated equalizing devices, (7) electrically controlled adjustable orifices or chokes, (8) flowing pressure and temperature transducers at subsurface safety valves, (9) electrically operated communication features for insert valves, (10) control line pressure transducers, (11) backup electrical actuators in case of hydraulic failure, (12) pH sensors at a valve to monitor control line or tubing fluids, (13) load cell communication to determine valve position, packing element, or a slip load, (14) constant power source for an electromagnetic valve, (15) proximity sensors for subsea actuators, (16) electrically operated lock open devices for a subsea actuator, (17) electrically operated lock close devices for a subsea actuator, (18) electrical permanent lock open device for subsurface safety valves, (19) electrical override for subsea actuator to open gate valve, and (20) electrical release mechanisms for subsea actuator to release connection between the actuator and the valve stem during removal. These are some of the applications, although many others can be employed without departing from the spirit of the invention.

To the extent the passages 18, 20, 22 can be isolated from each other, separate pressure signals in each path can be transmitted to a remote point such as subsea.

In the preferred embodiment, the spacer is made from extruded TEFZB which is a FIFE fluorocarbon material available from E.I. Dupont. In the preferred embodiment, if encapsulation of the spacer 12 is desired, an epoxysin, wh ich is a mixture of a plasticizer, a resin, and a curing agent, provides an effective gas/fluid block if the outer jacket 10 is compromised. Other materials can be used in lieu of the epoxy resin if they are pumpable and can provide the shock protection and gas/fluid blocking protection for the conductor 14. An alternative embodiment can be the provision of the outer covering over jacket 10 in a material called SANTOPREMEX, which is available from Monsanto Company, St. Louis, Missouri.

One of the advantages of the construction of the apparatus A is that the outer jacket 10 can be stripped off, as required, without damaging the inner conductor 14. In the preferred embodiment, a bundle of 18 gauge copper conductor forms the main conductor 14 running through the spacer 12. The use of the epoxy material, which acts as a substantially incompressible fluid, significantly increases the compressive and collapse strength. Under compression, the epoxy material acts as a cushion and provides additional protection that is not now available with other types of downhole cable. The exterior housing or jacket 10 also shields against electrical noise, while the entire assembly is economical and permits multiple reruns. The filler totally fills the flowpaths 18, 20, and 22, but partial filling is also within the scope of the invention.

In the preferred embodiment, the housing 10 has a seam which is electronbeam welded. The spoke-like profile of the preferred spacer 12 allows the insulation of the conductors 14 to be oriented during the welding process to put a seam between the two spokes, thereby reducing the possibility of contaminating the weld with insulation material and reducing the heat transfer from the insulation to the newly formed weld. The method of assembly thus improves the quality of the finished product. With the epoxy resin filler or other equivalent materials, the compressive strength of up to 30,000 psi is obtained.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made without departing from the spirit of the invention.

Claims (23)

CM AIMS

1. A tubing encased conductor apparatus comprising: an elongated housing having an interior and exterior face; at least one conductor extending through said housing; a spacer mounted to said conductor to distance said conductor from said interior face of said housing.

2. The apparatus of claim 1, wherein: said spacer extends along said conductor to form a hub which substantially covers said conductor as it extends through said housing.

3. The apparatus of claim 2, wherein said spacer further comprises: at least one extending member defining at least one flow passage extending between said covered conductor and said interior face of said tubing.

4. The apparatus of claim 2, further comprising: a filler material disposed between said hub and said interior face of said housing to lend additional shock protection to said conductor.

5. The apparatus of claim 3, wherein said spacer further comprises: a plurality of circumferentially spaced members radially extending from said hub.

6. The apparatus of claim 5, wherein: said flow passage is substantially filled with a filler material to lend additional shock protection for said conductor.

7. The apparatus of claim 5, wherein: said housing is formed from rolled sheet into a tube having a longitudinal seam to be welded; said seam oriented in a displaced location from said radially extending members.

8. The apparatus of claim 2, wherein: said spacer longitudinally covers a plurality of conductors shielded from each other with each conductor serving a discrete signal or power transmitting purpose.

9. The apparatus of claim 3, further comprising: at least one fluid-operated device; at least one electrically operated device; said flowpath connected to said fluid-actuated device for actuation thereof from an end of said housing extending to the surface; said conductor connected to said electrically actuated device to deliver power or to transmit electrical signals to and/or from said device.

10. A method of operation of downhole fluid and electrically operated components, comprising the steps of: extending a tubular housing from the surface to the fluidactuated component; providing at least one conductor cable in said tubular housing; spacing the cable with a spacer, away from the interior wall of said tubular housing; connecting one end of said cable to an electrically operated component; and transmitting electrical signals or power through said conductor cable.

11. The method of claim 10, further comprising the step of: providing fluid pressure to said fluid-operated component through said tubular housing.

12. The method of claim 11, further comprising the step of: covering said conductor cable in said tubular housing with said spacer.

13. The method of claim 12, further comprising the step of: providing as said spacer a tubular segment that encases said conductor; providing an extending segment from said tubular segment to form a flowpath between said tubular segment and the surrounding tubular housing.

14. The method of claim 13, further comprising the step of: providing at least one radially extending longitudinal fin from said tubular segment as said extending segment.

15. The method of claim 14, further comprising the step of: filling at least in part said flowpath with a filler material.

16. The method of claim 15, further comprising the step of: providing sufficient filler material to act as a gasiliquid block should said tubing from the surface become compromised.

17. The method of claim 14, further comprising the steps of: extruding said spacer having said tubular segment and said fin onto the conductor; forming as said tubular housing a flat material into a tube around said conductor covered by said extruded spacer; offsetting said fin from a seam formed by said formed flat material; and sealing said seam without damage to said fin.

18. The method of claim 14, further comprising the steps of: providing a plurality of fins extending radially and angularly spaced from each other, creating a plurality of longitudinal flowpaths in said tubing.

19. The method of claim 18, further comprising the step of: providing three fins at about 1200 spacing.

20. A tubing-encascd conductor assembly, comprising: a continuously encased conductor disposed within an elongated tube, said encasement providing positioning for the conductor away from said tube; and a filler material between said encased conductor and said tube.

21. The apparatus of claim 20, wherein: said encased conductor comprising a hub with at least one extending element to insulate and centralize said encased conductor in said tube. ~

22. A tubing encased conductor apparatus substantially as herein described with reference to the accompanying drawings.

23. A method of operation of downhole fluid and electrically operated components substantially as herein described with reference to the accompanying drawings.