Downhole electrode for well guidance system
First Claim
Patent Images
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.
2 Assignments
0 Petitions
Accused Products
Abstract
A borehole guidance system for guiding a well being drilled with respect to an existing reference well includes a multi-sectioned casing in the reference well. A selected section of the casing, usually the lowest section, is electrically conductive and the next adjacent section is electrically nonconductive. A wireline connects a current source on the surface to the selected conductive section to produce a reference current in the well. The reference current is injected into the earth and dissipated so that the current produces a reference magnetic field surrounding the well which is unaffected by return currents.
-
Citations
17 Claims
-
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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. Apparatus for producing a reference magnetic field in a borehole, comprising:
-
a reference well; a guided well adjacent said reference well and being drilled along a predetermined path with respect to said reference well; a casing within said reference well, said casing including multiple adjoined sections with a selected section of said casing being electrically conductive and an adjacent section of said casing being electrically nonconductive; a wireline in said casing, said wireline including an electrical conductor in electrical contact with said selected section to form an electrode; and a source of current connected to said wireline to produce a reference current in said wireline between said source and said electrode, said electrode being in electrical contact with the earth to inject said reference current into the earth. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
Specification