--> ABSTRACT: Importance of Rock Volumes in Log-Core Correlation, by Milton B. Enderlin, Diana K. T. Hansen, and Brian R. Hoyt; #91022 (1989)

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Importance of Rock Volumes in Log-Core Correlation

Milton B. Enderlin, Diana K. T. Hansen, Brian R. Hoyt

When cores, whether whole or sidewall, are taken from a well, the first task is to tie the core(s) to the open-hole logs. When the observed core data correlate marginally with the log data, a great deal of interest is generated about the quality and validity of the log in question and/or the core analysis technique. The difficulty encountered in log-log and log-core correlation can, in part, be attributed to an unclear sense of the volume of rock investigated by downhole logging tools and core analysis.

A marginal correlation from log to log or from log to core has often been blamed on a number of things, such as poor depth control, bad hole conditions, and clay volume. In fact, it may reflect influence due more to microscopic and mesoscopic formation heterogeneity. The vertical resolution and depth of investigation of the sampling device can be used to estimate the volume of rock investigated by the device. A good correlation between diverse measurements with differing rock volumes provides insight into the degree of homogeneity of the larger volume. A variety of rock volumes have been estimated, and these estimates should be used as a first pass at comparison between logs and cores.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.