Drill string inground isolator in an MWD system and associated method

摘要

An inground isolator and associated method can provide an electrically isolated break in a drill string using electrical insulating members/isolators that are supported by a housing. During drill string operations, the isolators are subject only compressive forces responsive to both extension (pushing) and retraction (pulling) by the drill string. The isolators can be formed from an electrically insulating material such as a ceramic material. An interchangeable inground tool system is described which integrally serves to provide an electrically isolating gap in the drill string.

主权项

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 first group of electrical isolators and a second group of electrical isolators; and a housing that defines a through passage along a length thereof and said housing is configured to support the first group and the second group in a spaced apart relationship along said length and surrounding the through passage such that, responsive to the drill rig pushing on the drill string, a first one of the first and second groups is subject to a first compressive force and responsive to the drill rig pulling on the drill string the other one of the first and second groups is subject to a second compressive force without subjecting either of the first and second groups to a tension force during said pushing and pulling by the drill rig to form an electrically isolating break in the drill string.