Gap assembly for EM data telemetry

Patent metadata

Field	Value
Publication number	US-10156102-B2
Application number	US-201515306040-A
Country	US
Kind code	B2
Filing date	May 8, 2015
Priority date	May 8, 2014
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

A gap sub has electrically-conductive parts held together by electrical insulators which engage in channels formed in the parts. The electrical insulators hold the parts in a spaced-apart electrically-insulated relationship. In some embodiments, the electrical insulators are removable to allow separation of the parts. An insulating oil or other fluid may fill the gap.

First claim

What is claimed is:

1. A gap assembly useful in subsurface drilling, the gap assembly comprising:
a drill string section having a longitudinal channel extending through it and a threaded pin at one end thereof for coupling to an adjacent drill string section wherein the drill string section comprises:
an electrically-conductive female portion having an outer surface which provides threads of the pin and an inner surface which defines a bore through the female portion; and,
an electrically-conductive male portion comprising a projecting part extending axially from a first end thereof, the projecting part extending into the bore through the female portion and projecting longitudinally into the threads of the pin;
wherein the male and female portions are radially spaced apart from one another and electrically-insulated from one another.

2. A gap assembly according to claim 1 comprising rigid electrically-insulating spacers located between the male and female portions.

3. A gap assembly according to claim 2 wherein the male portion comprises a first flange face on the first end of the male portion surrounding the projecting part and the female portion comprises a second flange face facing the first flange face and a first plurality of the electrically-insulating spacers are received between the first and second flange faces.

4. A gap assembly according to claim 2 wherein a second plurality of the electrically-insulating spacers are received between the projecting part of the male portion and the inner surface of the female portion.

5. A gap assembly according to claim 4 wherein the projecting part of the male portion and the inner surface of the female potion are each formed to provide axially-extending grooves and at least some electrically-insulating spacers of the second plurality of electrically-insulating spacers are received between the axially-extending grooves of the projecting part of the male portion and the inner surface of the female portion.

6. A gap assembly according to claim 2 wherein the spacers comprise ceramic balls.

7. A gap assembly according to claim 1 wherein the projecting part of the male portion is tubular and the longitudinal channel of the drill string section extends through the projecting part of the male portion.

8. A gap assembly according to claim 1 comprising a sleeve of an electrically-insulating material provided on the outside of a body of the male portion, the sleeve covering a portion of the body of the male portion that is closest to the female portion.

9. A gap assembly according to claim 8 wherein the electrically-insulating material is selected from the group consisting of a glass-reinforced plastic, PEEK and ceramic.

10. A gap assembly according to claim 8 wherein the sleeve has a length in the range of 1 inch (about 2 ½ cm) to 20 inches (about 50 cm).

11. A gap assembly according to claim 1 comprising an electronics package housed in a cavity located between the longitudinal passage and an outer surface of the male portion.

12. A gap assembly according to claim 11 wherein the electronics package comprises one or both of an electromagnetic (EM) telemetry transmitter and an EM telemetry receiver connected electrically to each of the male portion and the female portion.

13. A gap assembly according to claim 1 wherein the space between the male and female portions is filled with solid, electrically-insulating material.

14. A gap assembly according to claim 1 wherein the female portion is removably coupled to the male portion.

15. A gap assembly according to claim 14 wherein the female portion is one of first and second interchangeable female portions having different configurations of threads on their outer surfaces.

16. A gap assembly according to claim 1 wherein the threads of the pin extend along the female portion for at least one half of the length of the female portion.

17. A gap assembly according to claim 1 comprising a dielectric liquid or fluid sealed in the gap between the male and female portions.

18. A drill string comprising a mud motor coupled to drive a drill bit and a gap assembly according to claim 1 between the mud motor and the drill bit.

19. A gap assembly useful in subsurface drilling, the gap assembly comprising:
a drill string section having a longitudinal channel extending through it and a threaded pin at one end thereof for coupling to an adjacent drill string section wherein the drill string section comprises:
an electrically-conductive female portion having an outer surface which provides threads of the pin and an inner surface which defines a bore through the female portion;
an electrically-conductive male portion comprising a projecting part extending axially from a first end thereof, the projecting part extending into the bore through the female portion and projecting longitudinally into the threads of the pin; and
rigid electrically-insulating spacers located between the male and female portions;
wherein the male and female portions are spaced apart from one another and electrically-insulated from one another;
wherein the male portion comprises a first flange face on the first end of the male portion surrounding the projecting part and the female portion comprises a second flange face facing the first flange face and a first plurality of the electrically-insulating spacers are received between the first and second flange faces;
wherein the first and second flange faces each have a circumferentially-extending groove and the first plurality of the electrically-insulating spacers are received between the circumferentially-extending grooves of the first and second flange faces.

20. A gap assembly useful in subsurface drilling, the gap assembly comprising:
a drill string section having a longitudinal channel extending through it and a threaded pin at one end thereof for coupling to an adjacent drill string section wherein the drill string section comprises:
an electrically-conductive female portion having an outer surface which provides threads of the pin and an inner surface which defines a bore through the female portion;
an electrically-conductive male portion comprising a projecting part extending axially from a first end thereof, the projecting part extending into the bore through the female portion and projecting longitudinally into the threads of the pin; and
rigid electrically-insulating spacers located between the male and female portions;
wherein the male and female portions are spaced apart from one another and electrically-insulated from one another;
wherein a second plurality of the electrically-insulating spacers are received between the projecting part of the male portion and the inner surface of the female portion;
wherein the projecting part of the male portion and the inner surface of the female potion are each formed to provide one or more circumferentially-extending grooves and at least some electrically-insulating spacers of the second plurality of electrically-insulating spacers are received between the circumferentially-extending grooves of the projecting part of the male portion and the inner surface of the female portion.

21. A gap assembly according to claim 20 comprising one or more fill ports respectively connected to the circumferentially-extending grooves, wherein the fill ports are located in a compartment contained within the gap assembly.

22. A gap assembly according to claim 21 wherein the compartment is sealed against downhole pressures.

Assignees

• Evolution Engineering Inc

Inventors

• Derkacz Patrick R
• Logan Aaron W
• Logan Justin C

Classifications

• E21B17/003 Primary

  with electrically conducting or insulating means (E21B17/028 and E21B17/023 take precedence) · CPC title

• E21B47/13

  by electromagnetic energy, e.g. radio frequency · CPC title

• E21B4/02

  Fluid rotary type drives · CPC title

• E21B17/042

  Threaded · CPC title

• E21B47/122

  Fixed Constructions · mapped topic