Proof of feasibility of the through-casing resistivity technology. Final report, April 15, 1988-October 1, 1989
A downhole stop-hold-and-lock apparatus has successfully measured the resistivity of geological formations from within a cased well for the first time. These results show agreement with logs of the resistivity of the geological formations obtained before the casing was set. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. Two pairs of voltage measuring electrodes which are in electrical contact with the interior of the casing provide two voltage outputs which are subtracted to provide a differential voltage output which in turn provides a measurement of the differential current conducted into formation in the vicinity of said electrodes. A calibration and nulling procedure is used which minimizes the influence of variations in the thickness of the casing and in variations of electrode placements. Sinusoidal currents at typically 1 Hz are used which allow measurements of the resistivities of the adjacent geological formations.
- Research Organization:
- ParaMagnetic Logging, Inc., Woodinville, WA (USA)
- OSTI ID:
- 6282411
- Report Number(s):
- PB-91-118661/XAB; CNN: GRI-5088-212-1664
- Country of Publication:
- United States
- Language:
- English
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Methods and apparatus for measurement of the resistivity of geological formations from within cased boreholes
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Related Subjects
58 GEOSCIENCES
GEOLOGIC DEPOSITS
RESISTIVITY LOGGING
WELL LOGGING EQUIPMENT
DESIGN
BOREHOLES
CALIBRATION
COMPARATIVE EVALUATIONS
ELECTRIC POTENTIAL
ELECTRODES
PROGRESS REPORT
WELL CASINGS
WELL COMPLETION
WELLS
CAVITIES
DOCUMENT TYPES
ELECTRIC LOGGING
EQUIPMENT
WELL LOGGING
440400* - Well Logging Instrumentation
580000 - Geosciences