ELECTROMAGNETIC WELLBORE TELEMETRY SYSTEM FOR TUBULAR STRINGS

• US 20080041575A1
• Filed: 07/10/2006
• Published: 02/21/2008
• Est. Priority Date: 07/10/2006
• Status: Active Grant

• Current Assignee: IntelliServ, LLC (NOV, Inc.)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Clark, Brian, Niina, Nobuyoshi
• Granted Patent: US 7,605,715 B2
• Time in Patent Office: Days
• US Class Current: 166/65.1
• CPC Class Codes: E21B 17/003 with electrically conducting or insulating means E21B17/028 and E21B17/023 take precedence
• CPC Class Codes: E21B 17/0285 characterised by electrically insulating elements

Abstract

A coaxial transmission line for an electromagnetic wellbore telemetry system comprises an outer conductive pipe, an inner conductive pipe disposed coaxially inside an axial bore of the outer conductive pipe, a first electrical contact having a first contact face disposed at a first end of the inner conductive pipe, a second electrical contact having a second contact face disposed at a second end of the inner conductive pipe, wherein at least one of the first and second contact faces includes at least one slot, and an insulator disposed between the outer conductive pipe and the inner conductive pipe.

Claims

1. A coaxial transmission line for an electromagnetic wellbore telemetry system, comprising:

an outer conductive pipe;

an inner conductive pipe disposed coaxially inside an axial bore of the outer conductive pipe;

a first electrical contact having a first contact face disposed at a first end of the inner conductive pipe;

a second electrical contact having a second contact face disposed at a second end of the inner conductive pipe, wherein at least one of the first and second contact faces includes at least one slot; and

an insulator disposed between the outer conductive pipe and the inner conductive pipe.

2. The coaxial transmission line of claim 1, wherein the inner conductive pipe is selected from the group consisting of a slotted pipe, a perforated pipe, a solid pipe, and a flexible pipe having metallic strips.

3. The coaxial transmission line of claim 2, wherein the outer conductive pipe is selected from the group consisting of drill pipe, casing, tubing, and riser.

4. The coaxial transmission line of claim 1, wherein the first and second contact faces are made of a low-resistivity material.

5. The coaxial transmission line of claim 1, further comprising an annular seal retained at a distal end of the insulator.

6. The coaxial transmission line of claim 1, wherein the first electrical contact is a fixed contact and the second electrical contact is a moving contact.

7. The coaxial transmission line of claim 6, wherein at least one of the first and second contact faces includes at least one taper.

8. The coaxial transmission line of claim 6, wherein the second contact face is movably coupled to the inner conductive pipe by a spring member.

9. The coaxial transmission line of claim 8, wherein the second contact face is located at a terminal end of the spring member.

10. The coaxial transmission line of claim 8, wherein the spring member comprises a helical spring.

11. The coaxial transmission line of claim 6, wherein the second contact face is provided at a distal end of a tubular body coupled to the inner conductive pipe.

12. The coaxial transmission line of claim 11, wherein the tubular body has openings which allow flow circulation.

13. The coaxial transmission line of claim 12, further comprising a low-friction material between the tubular body and the insulator.

14. The coaxial transmission line of claim 6, wherein the outer conductive pipe includes a pin connector and a box connector at distal ends thereof.

15. The coaxial transmission line of claim 14, wherein the fixed contact is located at the pin connector and the moving contact is located at the box connector.

16. A coaxial transmission line for an electromagnetic wellbore telemetry system, comprising:

an outer conductive pipe;

a perforated or slotted inner conductive pipe disposed coaxially inside an axial bore of the outer conductive pipe;

a first electrical contact having a first contact face disposed at a first end of the inner conductive pipe;

a second electrical contact having a second contact face disposed at a second end of the inner conductive pipe; and

an insulator disposed between the outer conductive pipe and the inner conductive pipe.

17. The coaxial transmission line of claim 16, wherein the first contact is a fixed contact and the second contact is a moving contact.

18. The coaxial transmission line of claim 17, wherein at least one of the first and second contact faces includes at least one slot.

19. The coaxial transmission line of claim 18, wherein at least one of the first and second contact faces includes at least one taper.

20. The coaxial transmission line of claim 17, wherein the second contact face is movably coupled to the inner conductive pipe by a spring member.

21. The coaxial transmission line of claim 17, wherein the second contact face is provided at a distal end of a tubular body coupled to the inner conductive tube, said tubular body having openings which allow flow circulation.

22. The coaxial transmission line of claim 16, wherein the outer conductive pipe is selected from the group consisting of drill pipe, casing, tubing, and riser.

23. The coaxial transmission line of claim 16, wherein the outer conductive pipe includes a pin connector and a box connector at distal ends thereof.

24. The coaxial transmission line of claim 16, further comprising an annular seal retained at a distal end of the insulator.

25. An electromagnetic wellbore telemetry system, comprising:

a plurality of coaxial transmission lines coupled together in the form of a tubular string for an oilfield operation, each coaxial transmission line comprising;

an outer conductive pipe;

an inner conductive pipe disposed coaxially inside an axial bore of the outer conductive pipe;

a first electrical contact having a first contact face disposed at a first end of the inner conductive pipe;

a second electrical contact having a second contact face disposed at a second end of the inner conductive pipe, wherein at least one of the first and second contact faces includes at least one slot; and

an insulator disposed between the outer conductive pipe and the inner conductive pipe.

26. The electromagnetic wellbore telemetry system of claim 25, wherein each of the outer conductive pipe includes a box connector and a pin connector at distal ends thereof and wherein the coaxial transmission lines are coupled together by mating box connectors with pin connectors.

27. The electromagnetic wellbore telemetry system of claim 26, wherein the contacts are arranged at the pin and box connectors such that when the coaxial transmission lines are coupled together by the pin and box connectors, the first electrical contact in one pipe joint engages the second electrical contact in the adjacent pipe joint.

28. The electromagnetic wellbore telemetry system of claim 27, further comprising a downhole tool coupled to at least one of the coaxial transmission lines.

29. An electromagnetic wellbore telemetry system, comprising:

a plurality of coaxial transmission lines connected in the form of a tubular string for an oilfield operation, each coaxial transmission line comprising;

an outer conductive pipe;

a perforated or slotted inner conductive pipe disposed coaxially inside an axial bore of the outer conductive pipe;

a first contact disposed at a first end of the inner conductive pipe;

a second contact disposed at a second end of the inner conductive pipe; and

an insulator disposed between the outer conductive pipe and the inner conductive pipe.

30. A method of making a coaxial transmission line for an electromagnetic wellbore telemetry system, comprising:

attaching first and second electrical contacts to distal ends of an inner conductive pipe;

applying an insulator on the outer surface of the inner conductive pipe;

inserting the inner conductive pipe and insulator into an outer conductive pipe; and

expanding the inner conductive pipe to conform the inner conductive pipe to the inner geometry of the outer conductive pipe.

31. The method of claim 30, wherein expanding comprises inserting rollers into the inner conductive pipe and translating the rollers along the length of the inner conductive pipe in contact with the inner conductive pipe.

32. The method of claim 31, wherein the inner conductive pipe is a slotted or perforated pipe.

33. The method of claim 32, wherein the insulator comprises fiberglass.

34. The method of claim 33, wherein the insulator comprises epoxy.

35. The method of claim 34, further comprising saturating the fiberglass with epoxy and curing the epoxy.

36. A method of making a coaxial transmission line for an electromagnetic wellbore telemetry system, comprising:

attaching first and second electrical contacts to distal ends of an inner conductive pipe;

arranging an outer conductive pipe coaxially with the inner conductive pipe; and

disposing an insulator between the inner conductive pipe and the outer conductive pipe.

37. The method of claim 36, wherein the inner conductive pipe is a slotted or perforated pipe.

38. The method of claim 36, wherein the inner conductive pipe is a solid pipe.

39. The method of claim 36, wherein the insulator is fiberglass-epoxy.

40. A method of providing communication between a downhole tool in a wellbore penetrating an underground formation and a surface unit, comprising:

connecting a plurality of coaxial transmission lines together, each coaxial transmission line comprising an outer conductive pipe, an inner conductive pipe disposed coaxially inside an axial bore of the outer conductive pipe, a first electrical contact having a first contact face disposed at a first end of the inner conductive pipe, a second electrical contact having a second contact face disposed at a second end of the inner conductive pipe, and an insulator disposed between the outer conductive pipe and the inner conductive pipe, wherein at least one of the first and second contact faces includes at least one slot;

coupling the plurality of coaxial transmission lines to the downhole tool; and

establishing communication between the coaxial transmission lines and the surface unit.