Page 150 - Basic Well Log Analysis for Geologist

LITHOLOGY LOGGING AND MAPPING TECHNIQUES

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Figure 51. Example crossplot of formation resistivity (R,; in this case deep Laterolog*) versus neutron porosity (ay). This
comparison of log response to facies helps the geologist develop rock type clusters.
This example is from the Ordovician Red River C and D zones in Richland and Roosevelt counties, Montana. After
Asquith (1979).
Solid squares and circles represent wells with core or cuttings available, in addition to log response. Open circles represent
wells with log control only.

Facies classifications are first confirmed by core/cuttings analysis, but once clusters are established then, only log control is
necessary.