Seals and insulators for pipes having insulated electrical conductors

Abstract

A pipe segment having an insulated electrical conductor includes a first electrical contact disposed at one end of the conductor within the pipe segment, the conductor extending from an externally threaded connector at one end of the pipe segment to an internally threaded connector at the other end of the pipe segment. A second electrical contact is disposed at the other end of the insulated electrical conductor. When the external connector of one segment is joined to the internal connector of an adjacent segment, the first contact is electrically connected to the second contact in the adjacent segment. A seal disposed within the insulating layer on the inner wall of each respective pipe segment provides space beyond the end of the seal to enable the seal to flex inwardly under pressure, thereby relieving lubricant extruded from the connecting externally threaded and internally threaded ends.

Description

Background Art

[0001] The present disclosure relates to the field of metal pipes that can be used in well drilling. More particularly, the present disclosure relates to seals for connectors having such pipes with insulated electrical conductors to prevent fluid from creating an electrical short circuit between the electrical conductor and the metal pipe.

[0002] Canadian Patent No. 3,002,675, assigned to the assignee of the present disclosure, describes a structure and method for manufacturing a metallic conduit having an insulated electrical conductor therein. For example, such conduit can be used in drilling wells in the same manner as conventional threaded, segmented drill pipe, with the addition of an insulated electrical conductor to provide a power and signal path. Such a power and signal path can provide the ability to operate certain types of equipment in the well during drilling, and to communicate signals between the surface and such equipment using other power and signal devices at significantly higher power capacities and rates.

[0003] Generally speaking, a pipe fabricated according to the '675 patent includes electrical contacts mounted on each end of a selected length of an electrical conductor. The conductor is configured to expand radially without plastic deformation while correspondingly shortening longitudinally when inserted into a section of metal pipe. The metal pipe section may have machined features on its inner surface to longitudinally retain the electrical contacts in place. The inner surface of the pipe section may be covered with an insulating layer to electrically insulate the conductor from the pipe section.

[0004] An important aspect of the aforementioned pipe is a seal disposed in at least one longitudinal end of one of the pipe segments. This seal prevents fluid from entering the space between the electrical contacts and the inner wall of the pipe segment. This space exists due to the structure of the electrical contacts and the corresponding inner surface of the pipe segment. The functional criteria of this seal are as follows: it has as little impact as possible on the handling and use of the pipe (including during assembly and disassembly); and, as closely as possible to the foregoing, it prevents fluid from entering the aforementioned space. It is also desirable that this seal avoids closing the release path of thread lubricant (pipe dope) applied by the threads during assembly of the pipe segments. Summary of the Invention

[0005] One aspect of the present disclosure is a pipe segment having an insulated electrical conductor. The pipe segment according to this aspect includes a first electrical contact, which is disposed at one end of the electrical conductor inside the pipe segment, from an externally threaded connector at one end of the pipe segment to an internally threaded connector at the other end of the pipe segment. A second electrical contact is disposed at the other end of the insulated electrical conductor. When the external connector on one pipe segment is engaged to the internal connector of an adjacent pipe segment, the first electrical contact is electrically connected to the second electrical contact in the adjacent segment. A seal inside the insulating layer disposed on the inner wall of each respective pipe segment provides space beyond the end of the seal to enable the seal to flex inwardly under pressure, thereby relieving pressure from lubricant extruded by connecting the externally threaded end and the internally threaded end.

[0006] In some embodiments, the seal comprises an elastomer.

[0007] In some embodiments, the elastomer comprises polyurethane or nitrile rubber.

[0008] In some embodiments, at least one of the first electrical contact and the second electrical contact includes a groove, and the seal includes an internal shoulder for engaging the groove.

[0009] In some embodiments, the seal includes an outer lip to maintain energized sealing contact with an inner wall of the space after the seal flexes inwardly.

[0010] Some embodiments further include at least one pressure relief port in at least one of the first and second electrical contacts.

[0011] Other aspects and possible advantages will be apparent from the following description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 shows a pre-assembled view of a pipe segment that can be manufactured and used according to the present invention.

[0013] FIG. 2 shows a perspective view of two adjacent pipe sections as in FIG. 1 before threaded assembly.

[0014] FIG. 3 shows a cross-sectional view of the pipe section of FIG. 2 before threaded connection.

[0015] FIG. 4 shows an enlarged cross-sectional view of the pipe section of FIG. 3 after the threads are fully engaged.

[0016] 5 and 6 each illustrate perspective side views of electrical contacts that may be used in some embodiments. DETAILED DESCRIPTION

[0017] FIG1 shows a “wired” pipe section or “joint” prior to assembling an electrical conductor 18 to a joint 10 of a pipe (e.g., drill pipe). The pipe joint 10 may include an internally threaded end 12 having internal threads 12A, for example, tapered threads made according to the intended use of the pipe joint 10. By way of example and not limitation, the threads 12A may be American Petroleum Institute (API) internal flush (IF) type threads. The other end of the pipe joint 10 may include an externally threaded end 14 having external threads 14A shaped to engage with internal threads (see 12A) on an adjacent pipe joint. As will be familiar to those skilled in the art, such threads make it possible to assemble a pipe consisting of multiple such joints into any selected length. The pipe joint 10 may include an electrical insulating layer 16 disposed on an inner surface of the pipe joint 10. The types of insulating materials and techniques for securing the insulating layer 16 are disclosed in Canadian Patent No. 3,002,675, assigned to the assignee of the present disclosure.

[0018] An electrical conductor assembly 18, including an electrical conductor 18A having corresponding electrical contacts at each longitudinal end, shown as a first contact 20 and a second contact 22, can be inserted into the pipe fitting 10 and radially expanded to conform to the inner wall of the pipe fitting 10. As described in Canadian Patent No. 3,002,675, the structure of the electrical conductor 18A radially expands without plastic deformation while simultaneously contracting longitudinally to seat the electrical contacts 20, 22 in corresponding arrangements formed in the inner wall of the pipe fitting 10.

[0019] FIG2 shows a perspective view of the threaded end of one pipe fitting 10 prior to assembly to an adjacent pipe fitting 10. External threads 14A on externally threaded end 14 are positioned for assembly adjacent to internally threaded end 12 on an adjacent pipe fitting 10. Electrical contacts 20 and electrical insulation 16 can be seen adjacent to externally threaded end 14 in FIG2 .

[0020] FIG3 illustrates a more complete view of the foregoing, showing the internal components of two threaded ends on adjacent pipe fittings. The view in FIG3 is taken just before the threaded connection between adjacent pipe fittings 10 is initiated. The electrical contact 20 in the externally threaded end 14 can be maintained in its radial position within the pipe fitting 10 by a support or spacer 17 or similar structure, because the electrical contact 20 does not extend radially and bond to the inner wall of the pipe through an intermediate insulator 16, as does the electrical conductor ( 18A in FIG1 ). The details of the electrical conductor and its assembly into the pipe fitting 10 and the electrical contact 20 (first electrical contact, hereinafter referred to as the "contact") can be similar to those described in Canadian Patent No. 3,002,675, although the structure disclosed therein is not intended to limit the scope of the present disclosure. An adjacent electrical contact 22 (second contact, hereinafter referred to as the "adjacent" electrical contact) is disposed in the internally threaded end 12 of the adjacent pipe fitting 10. Exemplary embodiments of the adjacent electrical contact 22 and its connection to the electrical contact 20 will be further explained with reference to FIG5 and FIG6 . The adjacent electrical contact 22 may include a seal 30 on its outer surface. The adjacent electrical contact 22 and seal 30 extend longitudinally from the threaded base 12B of the internally threaded end 12, such that the adjacent electrical contact 22 forms a good electrical connection with the electrical contact 20, and the seal 30 engages the electrical contact 20 to prevent fluid from entering the space 19 between the electrical contact 20 and the inner wall of the pipe fitting 10. This seal maintains electrical insulation between the electrical conductor (18 in FIG. 1 ) and the pipe fitting 10. In the exemplary embodiment shown in FIG. 3 , the seal 30 may include an internal shoulder 30A that fits into a corresponding external groove 24 in the adjacent electrical contact 22. In other embodiments, similar grooves may be formed in the electrical contact 20, and the seal 30 may be positioned thereon; the exemplary embodiment shown in FIG. 3 is merely one example of how the seal 30 may be configured to maintain its longitudinal position. The shoulder 30A is provided for convenience only and may be omitted or positioned elsewhere in some embodiments. For example, in some embodiments, a groove (not shown) may be formed in the inner wall of either fitting to accommodate a corresponding outer lip or shoulder (not shown) on the seal 30 .

[0021] For example, seal 30 may be made from any suitable elastomer, such as, but not limited to, polyurethane and nitrile rubber, that is capable of withstanding the fluid pressures and temperatures to which pipe segment 10 is exposed.

[0022] FIG4 shows an enlarged view of the fitting 10 of FIG3 , with the threads 14A on the externally threaded end 14 of one fitting 10 fully engaged with the corresponding threads 12A on the internally threaded end 12 of the adjacent fitting 10. When the threads are so engaged, the (first) electrical contact 20 and the adjacent (second) electrical contact 22 are in electrical contact with each other. Simultaneously, the seal 30 moves into the void space 19 between the electrical contact 20 and the interior of the externally threaded end 14. Thus, the seal 30 prevents fluid from entering the void space 31 between the engaged threads 12A, 14A, thereby electrically isolating the electrically contacted electrical contacts 20, 22 from the fitting 10. The seal 30 may include an outer lip or ring 30B to allow the seal 30 to flex radially inwardly somewhat while still electrically contacting against the interior wall of the fitting 10, which may be further defined by the insulating layer 16, for example. In this way, a relief space 19 can be provided between the inner wall of the adjacent pipe fitting 10 and the exterior of the seal 30, so that thread lubricant (pipe dope) can be squeezed into the relief space 19. This arrangement enables the pipe fitting to be threaded without providing an additional relief device to release the pressure of the squeezed thread lubricant. The seal 30 can be formed so that a relief space 19A exists radially between the contacts 20 and / or adjacent contacts 22, thereby allowing some inward bending of the seal 30, thereby making it easier for the lubricant under pressure to be discharged into the relief space 19. In some embodiments, one or more pressure relief ports 34 can be provided to allow excess thread lubricant to be discharged to the interior of the pipe fitting 10.

[0023] 5 and 6 illustrate adjacent electrical contacts 22 in greater detail. Electrical contact 22A may include a portion 22D thereof that may be assembled, for example, into a connector that intersects an end of an electrical conductor, as more fully described in Canadian Patent No. 3,002,675. Electrical contact 22A may include a flange located at a longitudinal end of electrical contact 22A that may be cut or otherwise formed to form contact ring 22B from the flange. In this exemplary embodiment, wedge-shaped recesses 22C on opposing circumferential sides of electrical contact 22A may be formed, for example, by electrode discharge machining, such that when contact ring 22B is axially pressed against an axial end face of a pin-end electrical contact (20 in FIG. 4), contact ring 22B may be deflected by an axial force applied to contact ring 22B. In this embodiment, the adjacent electrical contact 22 may be made of a conductive material having an elastic limit lower than the bending strain applied to the contact ring 22B when the contact ring 22B is pressed against the pin end electrical contact ( 20 in FIG. 4 ).

[0024] Based on the principles and exemplary embodiments described and illustrated herein, it will be appreciated that the arrangements and details of the exemplary embodiments may be modified without departing from these principles. The foregoing discussion has focused on specific embodiments, but other configurations are also contemplated. In particular, even though expressions such as "embodiments" are used herein, these phrases are intended to refer generally to the possibilities of embodiments and are not intended to limit the present disclosure to specific embodiment configurations. As used herein, these terms may refer to the same or different embodiments, which may be combined into other embodiments. In general, any embodiment cited herein may be freely combined with any one or more of the other embodiments cited herein, and any features of different embodiments may be combined with each other, unless otherwise stated. Although only a few examples have been described in detail above, it will be readily understood by those skilled in the art that many modifications are possible within the scope of the described examples. Therefore, all such modifications are intended to be included within the scope of the present disclosure as defined in the following claims.

Claims

1. A pipe section having an insulated electrical conductor, comprising: a first electrical contact disposed at one end of an insulated electrical conductor extending within the pipe segment from an externally threaded connection at one longitudinal end of the pipe segment to an internally threaded connection at another longitudinal end of the pipe segment; a second electrical contact at the other end of the insulated electrical conductor, the first electrical contact being configured to electrically connect with the second electrical contact in the adjacent pipe segment when the externally threaded connector on one pipe segment is engaged to the internally threaded connector on the adjacent pipe segment; A seal is disposed within an insulating layer on an inner wall of each respective pipe segment, providing a space beyond a longitudinal end of the seal between at least one of the first and second electrical contacts and the insulating layer, wherein the space enables the seal to flex radially inwardly under pressure to relieve thread lubricant expelled by connecting the male and female threaded ends.

2. The pipe section according to claim 1, wherein The seal comprises an elastomer.

3. The pipe section according to claim 2, wherein: Elastomers include polyurethane or nitrile rubber.

4. The pipe section according to claim 1, wherein At least one of the first electrical contact and the second electrical contact includes a groove, and the seal includes an internal shoulder for engaging the groove.

5. The pipe section according to claim 1, wherein The seal includes an outer lip to maintain energized sealing contact with the inner wall of the space after the seal flexes radially inwardly.

6. The pipe segment of claim 1, further comprising at least one pressure relief port in at least one of the first and second electrical contacts, the at least one pressure relief port providing pressure communication between the space and the interior of the pipe segment.

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