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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 of 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.
Inventors:
 [1]
  1. (Bothell, WA)
Issue Date:
OSTI Identifier:
870669
Assignee:
Paramagnetic Logging, Inc. (Woodinville, WA) RLO
Patent Number(s):
US 5570024
Contract Number:
FG06-84ER13294; FG22-88BC14243; FG22-90BC14617; FG22-93BC14966
Research Org:
ParaMagnetic Logging, Inc. (Bothell, WA)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
determining; resistivity; formation; adjacent; borehole; casing; multiple; electrodes; resistances; defined; methods; operation; types; electrode; apparatus; vertically; disposed; cased; measure; information; related; geological; formations; inside; minimum; spaced; apart; voltage; measurement; electrically; engage; interior; obtained; current; caused; flow; compensation; resistance; pair; determine; magnitude; multiple electrodes; apart voltage; vertically disposed; voltage measurement; measurement electrodes; geological formations; spaced apart; electrode apparatus; multiple electrode; adjacent geological; formation resistivity; geological formation; formation adjacent; measure information; apparatus vertically; casing resistance; information related; determining resistivity; electrically engage; /324/