US 5,074,365 AGranted

Borehole guidance system having target wireline

AssigneeVector Magnetics, Inc.

InventorArthur F. Kuckes

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Abstract

A method for guiding a borehole with respect to a target wireline carrying low frequency alternating current is disclosed. A wireline carrying an electrode at its terminal end is positioned in a target cased or uncased borehole with the electrode contact the wall of the borehole. An AC source is connected between the wireline and ground to supply current to the borehole wall near the bottom of the borehole. A sensor is positioned in a borehole being drilled to sense the magnetic field generated by current flow in the wireline, the sensor being spaced sufficiently far along the wireline from the electrode location to prevent magnetic fields due to return current through the target borehole casing on through the ground surrounding the target borehole from significantly affecting the sensor. The sensor measures the net alternating magnetic field to determine the direction to the target borehole, to permit guidance of the borehole drilling.

Claims16

Dependent claims

A method for producing drainage well segments adjacent lower ends of corresponding individual producer wells in an oil well field incorporating a plurality of producer wells, comprising:

a) partially drilling a rescue well in a region adjacent a field of producer wells;
b) selecting a target producer well within the field of producer wells;
c) lowering into said target producer well a wireline carrying an electrode to contact a bottom portion of the target well;
d) supplying a low-frequency alternating current through said wireline to said electrode, said current flowing into the target well to thereby produce an alternating magnetic field surrounding the target well;
e) lowering into the rescue well a magnetic field sensor having an axis of maximum sensitivity;
f) aligning the axis of said magnetic field sensor within the axis of the rescue well near the end thereof to measure the component of said alternating magnetic field which is parallel to the axis of said sensor;
g) determining from the measured component of said alternating field the direction from the rescue well to the target well;
h) controlling the direction of further drilling of the rescue well in accordance with the determined direction to said target well to cause said rescue well to closely pass said target well without intersection;
i) drilling said rescue well to a predetermined distance past said target well;
and
j) segmenting an end portion of said rescue well to provide supplemental drainage of said oil bearing strata for said target producer well.

8 more elements

Dependencies are inferred from the claim text.