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Fundamental Approach to Dipmeter Analysis

Milton B. Enderlin, Diana K. T. Hansen

Historically, in dipmeter analysis, depositional patterns are delineated for environmental, structural, and stratigraphic interpretations. The proposed method is a fundamental approach using raw data measurements from the dipmeter sonde to help the geologist describe subsurface structures on a stratigraphic scale. Raw data are available at the well site, require no post-processing, are cost effective, easy to use, require only a basic understanding of sedimentary features and facies, and can be combined with computed results. A case study illustrates the reconstruction of sedimentary features from a raw data log recorded by a six-arm dipmeter.

The dipmeter is a wireline tool with a series of evenly spaced, focused electrodes applied to the circumference of the borehole wall. The raw data are presented as curves representing the electrode response and tool orientation. In outcrop, the geologist usually can see an entire sedimentary feature in a large perspective, that is, with the surrounding landscape. Therefore, a large range of features can be resolved. However, in the borehole environment the perspective is reduced to the borehole diameter, thus reducing the range of recognizable features. In this study, a table was assembled that identifies the features distinguished by the proposed method as a function of borehole diameter.

AAPG Search and Discovery Article #91031©1988 AAPG Eastern Section, Charleston, West Virginia, 13-16 September 1988.