Advanced drill string inground isolator housing in an MWD system and associated method

• US 9,422,802 B2
• Filed: 03/14/2013
• Issued: 08/23/2016
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Chau, Albert W., Theimer, Kenneth J.
• Primary Examiner(s): WRIGHT, GIOVANNA COLLINS
• Application Number:
  US13/827,945
• Publication Number:
  US 20140262513A1
• Time in Patent Office: 1,258 Days
• US Class Current: 1/1
• CPC Class Codes: E21B 17/003 with electrically conducting or insulating means E21B17/028 and E21B17/023 take precedence
• CPC Class Codes: E21B 47/01 Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like
• CPC Class Codes: E21B 47/013 Devices specially adapted for supporting measuring instruments on drill bits
• CPC Class Codes: E21B 47/017 Protecting measuring instruments
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 7/046 horizontal drilling drilling with mechanical conveying means E21B7/003

Abstract

A housing defines a through passage along its length and is configured to support a group of electrical isolators surrounding the through passage to form an electrically isolating break in a drill string such that each isolator of the group of isolators is subject to no more than a compressive force responsive to extension and retraction of the drill string. The housing defines a housing cavity to receive an electronics package having a signal port and is configured for electrical connection of the signal port across the electrically isolating break. A housing lid can cooperate with a main housing body to define elongated slots for purposes of enhancing the emanation of a locating signal. A housing arrangement can support electrical connections from an electronics package to bridge an electrically isolating gap.

Claims

1. An apparatus for use in combination with a drill string that is electrically conductive and extends from an inground distal end, that includes an inground tool, to a drill rig, said apparatus comprising:

a group of electrical isolators; and

a housing that defines a through passage along a length thereof and said housing is configured to support the electrical isolators surrounding the through passage to form an electrically isolating break in the drill string such that, responsive to the drill rig pushing on the drill string and responsive to the drill rig pulling on the drill string, each isolator of the group of isolators is subject to no more than a compressive force and the housing defines a housing cavity to receive an electronics package having a signal port and configured for electrical connection of the signal port across the electrically isolating break.

2. The apparatus of claim 1 configured for insertion into the drill string to thereafter form part of an overall length of the drill string.

3. The apparatus of claim 1 configured to form part of said inground tool.

4. The apparatus of claim 1 wherein the group of electrical isolators is formed from a ceramic material.

5. The apparatus of claim 4 wherein the ceramic material is selected as at least one of a toughened zirconia and a silicon nitride ceramic.

6. The apparatus of claim 5 wherein each isolator includes a solid core.

7. The apparatus of claim 1 wherein each electrical isolator is spherical in configuration.

8. The apparatus of claim 1 wherein said isolators are captured by the housing around a centerline of the housing.

9. The apparatus of claim 8 wherein said housing supports twelve of the isolators.

10. The apparatus of claim 1 wherein said compressive force is applied to opposing side margins of a spherical outer surface of each isolator.

11. The apparatus of claim 1 wherein said housing includes an intermediate housing that is configured to engage a main housing with said isolators captured therebetween.

12. The apparatus of claim 11 wherein the intermediate housing includes first and second opposing ends such that the second end defines a peripheral endwall and the main housing includes first and second opposing main housing ends with the first main housing end defining a peripheral side margin that is arranged in a confronting relationship with the peripheral endwall of the intermediate housing to cooperatively define a plurality of pockets that such that one of the isolators is captured in each pocket.

13. The apparatus of claim 12 wherein the intermediate housing defines an internal passage to rotationally receive an extension of the main housing and the extension defines an aperture to removably receive a main assembly bolt in electrical contact with the main housing such that the main assembly bolt applies a preload compression force to the isolators.

14. The apparatus of claim 1 wherein each one of said group of electrical isolators includes an identical peripheral outline and said housing captures the electrical isolators of the group in a uniformly spaced apart distribution around a centerline of the housing.

15. The apparatus of claim 14 wherein each one of said group of electrical isolators is spherical in configuration.

16. The apparatus of claim 15 wherein each spherical isolator is formed having a solid core.