Method and apparatus for resistivity imaging in boreholes with an antenna and two spaced apart electrodes
First Claim
1. An apparatus configured to evaluate an earth formation, the apparatus comprising:
- at least one antenna on a downhole assembly, the at least one antenna including an antenna with a coil having an axis substantially parallel to an axis of the downhole assembly configured to be conveyed in a borehole in the earth formation and induce an electrical current in the earth formation upon activation of the at least one antenna; and
at least two azimuthally spaced apart electrodes in proximity to the formation, a difference in electrical potential between the at least two electrodes responsive to the induced electrical current being indicative of a property of the earth formation.
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Accused Products
Abstract
An apparatus, method and computer-readable medium for evaluating an earth formation are disclosed. The apparatus includes at least one coil on a logging tool conveyed in a borehole in the earth formation. Passage of a current through the coil induces an electrical current in the earth formation. At least two electrodes associated with the logging tool and in proximity to a wall of the borehole have a potential difference in response to the induced electrical current that is indicative of a property of the earth formation. The at least one coil may be mounted on a mandrel of a downhole assembly. The electrodes may be positioned on a first pad extendable from a mandrel of the downhole assembly.
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Citations
21 Claims
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1. An apparatus configured to evaluate an earth formation, the apparatus comprising:
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at least one antenna on a downhole assembly, the at least one antenna including an antenna with a coil having an axis substantially parallel to an axis of the downhole assembly configured to be conveyed in a borehole in the earth formation and induce an electrical current in the earth formation upon activation of the at least one antenna; and at least two azimuthally spaced apart electrodes in proximity to the formation, a difference in electrical potential between the at least two electrodes responsive to the induced electrical current being indicative of a property of the earth formation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of evaluating an earth formation, the method comprising:
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(a) passing a current through at least one antenna including an antenna with a coil having an axis substantially parallel to an axis of a downhole assembly conveyed in a borehole in the earth formation to induce and inducing an electrical current in the earth formation; and (b) measuring a difference in electrical potential between at least two azimuthally spaced apart electrodes in proximity to the formation resulting from the induced electrical current, and (c) determining from the difference a resistivity property of the earth formation. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A non-transitory computer readable medium product having stored thereon instructions that when read by a processor cause the processor to execute a method, the method comprising:
determining a property of an earth formation from a difference in electrical potential between at least two azimuthally spaced apart electrodes proximate a wall of a borehole in the earth formation responsive to an electrical current induced in the earth formation upon activation of an antenna including an antenna with a coil having an axis substantially parallel to an axis of a downhole assembly conveyed in the borehole. - View Dependent Claims (21)
Specification