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A FORTRAN algorithm for correcting normal resistivity logs for borehole diameter and mud resistivity

Open-File Report 78-669

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Abstract

The FORTRAN algorithm described in this report was developed for applying corrections to normal resistivity logs of any electrode spacing for the effects of drilling mud of known resistivity in boreholes of variable diameter. The corrections are based on Schlumberger departure curves that are applicable to normal logs made with a standard Schlumberger electric logging probe with an electrode diameter of 8.5 cm (3.35 in). The FORTRAN algorithm has been generalized to accommodate logs made with other probes with different electrode diameters. Two simplifying assumptions used by Schlumberger in developing the departure curves also apply to the algorithm: (1) bed thickness is assumed to be infinite (at least 10 times larger than the electrode spacing), and (2) invasion of drilling mud into the formation is assumed to be negligible. * The use of a trade name does not necessarily constitute endorsement by the U.S. Geological Survey.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
A FORTRAN algorithm for correcting normal resistivity logs for borehole diameter and mud resistivity
Series title:
Open-File Report
Series number:
78-669
Edition:
-
Year Published:
1978
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
12 leaves ;27 cm.; (13 p. - PGS)