Centralizer for downhole probes

Patent metadata

Field	Value
Publication number	US-9523246-B2
Application number	US-201314073757-A
Country	US
Kind code	B2
Filing date	Nov 6, 2013
Priority date	Nov 6, 2012
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

An assembly for use in subsurface drilling includes a downhole probe supported by a centralizer. The centralizer comprises a tubular member that extends around the downhole probe. A wall of the centralizer is fluted to provide inward contact points that support the downhole probe and outward contact points that bear against a bore wall of a section of drill string. The downhole probe may be supported for substantially its entire length.

First claim

What is claimed is:

1. A centralizer for use in subsurface drilling, the centralizer comprising:
an elongated tubular member having a wall formed to provide a cross-section that provides first outwardly-convex and inwardly-concave lobes, the first lobes arranged to contact a bore wall of a bore in a section of drill string at a plurality of spots spaced apart around a circumference of the bore wall; and
a plurality of inwardly-projecting portions, each of the plurality of inwardly-projecting portions arranged between two adjacent ones of the plurality of first lobes.

2. A centralizer according to claim 1 wherein the inwardly-projecting portions comprise inwardly-projecting lobes that are inwardly-convex and outwardly-concave.

3. A centralizer according to claim 2 wherein the inwardly-projecting lobes are mirror symmetrical about an axis passing through a longitudinal centerline of the centralizer.

4. A centralizer according to claim 2 wherein a thickness of the wall is substantially uniform.

5. A centralizer according to claim 3 wherein the wall has a thickness in the range of about 0.1 to 0.3 inches.

6. A centralizer according to claim 4 wherein the wall has a thickness of 0.15 to 0.25 inches.

7. A centralizer according to claim 2 wherein, in cross-section the centralizer has 4-fold rotational symmetry.

8. A centralizer according to claim 1 wherein the cross-section provides four first lobes.

9. A centralizer according to claim 1 wherein the cross-section provides two to eight first lobes.

10. A centralizer according to claim 1 wherein each of the plurality of first lobes is mirror symmetrical about an axis passing through a longitudinal centerline of the centralizer.

11. A centralizer according to claim 1 wherein the first lobes are equally angularly separated around a longitudinal centerline of the centralizer.

12. A centralizer according to claim 1 wherein the first lobes provide longitudinally-extending ridges on an outer surface of the centralizer.

13. A centralizer according to claim 12 wherein the longitudinally-extending ridges are parallel to a longitudinal centerline of the centralizer.

14. A centralizer according to claim 12 wherein the longitudinally-extending ridges twist in helices around the longitudinal centerline of the centralizer.

15. A centralizer according to claim 1 wherein the wall of the centralizer comprises a thermoplastic material.

16. A centralizer according to claim 15 wherein the thermoplastic material comprises a fiber-filled thermoplastic material.

17. A centralizer according to claim 16 wherein the thermoplastic material comprises PEEK or PET.

18. A centralizer according to claim 1 wherein the wall is made of an electrically insulating material.

19. A centralizer according to claim 1 wherein the wall is made of an electrically conductive material.

20. A centralizer according to claim 1 wherein the wall is made of a composite of electrically conductive and electrically-insulating materials.

21. A centralizer for use in subsurface drilling, the centralizer comprising:
an elongated tubular member having a wall formed to provide a cross-section that provides first outwardly-convex and inwardly-concave lobes, the first lobes arranged to contact a bore wall of a bore in a section of drill string at a plurality of spots spaced apart around a circumference of the bore wall; and
a plurality of inwardly-projecting portions, each of the plurality of inwardly-projecting portions arranged between two adjacent ones of the plurality of first lobes wherein each of the plurality of first lobes has a radius of curvature that is less than a radius of a smallest circle enclosing the centralizer.

22. A downhole assembly comprising:
a drill string section having a bore extending longitudinally through the drill string section;
a downhole probe located in the bore of the section; and,
a centralizer in the bore, the centralizer comprising a tubular member having a wall extending around the downhole probe, the wall formed to contact an inside surface of the bore and an outside surface of the downhole probe, a cross-section of the wall following a path around the downhole probe that zig zags back and forth between the outside surface of the downhole probe and the inside surface of the bore wall.

23. A downhole assembly according to claim 22 wherein the wall divides an annular region within the bore surrounding the downhole probe into a plurality of channels, a first plurality of the channels being inside the wall of the centralizer and a second plurality of the channels being outside the wall of the centralizer.

24. A downhole assembly according to claim 22 wherein the downhole probe comprises an electronics package.

25. A downhole assembly according to claim 22 wherein the downhole probe comprises a metal housing and the metal housing is harder than a material of the centralizer wall.

26. A downhole assembly according to claim 22 wherein the downhole probe comprises a telemetry signal generator.

27. A downhole assembly according to claim 22 wherein following the path around the cross section, the path has inner portions that contact the outside of the downhole probe but do not contact the inside of the bore that alternate with outer portions that contact the inside surface of the bore but do not contact the downhole probe.

28. A downhole assembly according to claim 27 wherein the inner and outer portions of the path are connected by connecting portions of the path that extend through the bore.

29. A downhole assembly according to claim 28 wherein the connecting portions are curved.

30. A downhole assembly according to claim 28 wherein the connecting portions have compound curvature.

31. A downhole assembly according to claim 22 wherein the wall of the centralizer is formed to provide a cross-section that provides:
first outwardly-convex and inwardly-concave lobes, the first lobes contacting a bore wall of the bore of the drill string section at a plurality of spots spaced apart around a circumference of the bore wall; and
a plurality of inwardly-projecting portions, each of the plurality of inwardly-projecting portions arranged between two adjacent ones of the plurality of first lobes.

32. A downhole assembly according to claim 31 wherein, in the centralizer, the inwardly-projecting portions comprise inwardly-projecting lobes that are inwardly-convex and outwardly-concave.

33. A downhole assembly comprising:
a drill string section having a bore extending longitudinally through the drill string section;
a downhole probe located in the bore of the section; and,
a centralizer in the bore, the centralizer comprising a tubular member having a wall extending around the downhole probe, the wall formed to contact an inside surface of the bore and an outside surface of the downhole probe, a cross-section of the wall following a path around the downhole probe that zig zags back and forth between the outside surface of the downhole probe and the inside surface of the bore wall
wherein the downhole probe comprises a layer of a vibration damping material between a housing of the downhole probe and the centralizer.

Assignees

• Evolution Engineering Inc

Inventors

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

Classifications

• E21B47/135

  using light waves, e.g. infrared or ultraviolet waves · CPC title

• E21B47/13

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

• E21B7/00

  Special methods or apparatus for drilling · CPC title

• E21B47/18

  through the well fluid {, e.g. mud pressure pulse telemetry} · CPC title

• E21B23/01

  for anchoring the tools or the like (E21B23/02 - E21B23/06 take precedence; anchoring of drives in the borehole E21B4/18) · CPC title