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Title: Determining resistivity of a formation adjacent to a borehole having casing using multiple electrodes and with resistances being defined between the electrodes

Methods of operation are disclosed for different types of multiple electrode apparatus vertically disposed in a cased well to measure information related to the resistivity of adjacent geological formations from inside the cased well. The multiple electrode apparatus have a minimum of three spaced-apart voltage measurement electrodes that electrically engage the interior of the cased well. Measurement information is obtained related to current which is caused to flow from the cased well into the adjacent geological formation. First compensation information is obtained related to a first casing resistance between a first pair of the spaced-apart voltage measurement electrodes. Second compensation information is obtained related to a second casing resistance between a second pair of the spaced-apart voltage measurement electrodes. The measurement information, and first and second compensation information are used to determine a magnitude related to the adjacent formation resistivity. 13 figs.
Inventors:
Issue Date:
OSTI Identifier:
392633
Assignee:
Paramagnetic Logging, Inc., Woodinville, WA (United States) PTO; SCA: 440400; 580000; PA: EDB-96:167196; SN: 96001682412
Patent Number(s):
US 5,570,024/A/
Application Number:
PAN: 8-083,615; CNN: Contract GRI 5088-212-1664
Contract Number:
FG06-84ER13294; FG22-88BC14243; FG22-90BC14617; FG22-93BC14966
Resource Relation:
Other Information: PBD: 29 Oct 1996
Research Org:
Paramagnetic Logging Inc
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
44 INSTRUMENTATION, INCLUDING NUCLEAR AND PARTICLE DETECTORS; 58 GEOSCIENCES; WELL LOGGING EQUIPMENT; DESIGN; GEOLOGIC DEPOSITS; RESISTIVITY LOGGING; OPERATION; DATA ACQUISITION; ELECTRIC CONDUCTIVITY; WELL CASINGS

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