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Downhole electrode for well guidance system

  • US 5,676,212 A
  • Filed: 04/17/1996
  • Issued: 10/14/1997
  • Est. Priority Date: 04/17/1996
  • Status: Expired due to Term
First Claim
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1. A method for providing a reference magnetic field in a cased reference borehole, comprising:

  • locating a wireline within a sectioned casing in a reference borehole;

    producing a current in said wireline said current producing a reference magnetic field in the earth surround the borehole;

    injecting said current from said wireline into the earth surrounding the borehole by way of an electrode section of the casing at the bottom of the borehole; and

    inhibiting said injected current from flowing in casing sections other than said electrode section.

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