Interpreting Wireline Measurements in Coal Beds

JOHNSTON, DAVID J., Schlumberger Well Services, Aurora, CO

When logging coal seams with wireline tools, the interpretation method needed to evaluate the coals is different from that used for conventional oil and gas reservoirs. Wireline logs identify coals easily. For an evaluation, the contribution of each coal component on the raw measurements must be considered.

This paper will discuss how each log measurement is affected by each component. The components of a coal will be identified as the

mineral matter, macerals, moisture content, rank, gas content, and cleat porosity. The measurements illustrated are from the resistivity, litho-density, neutron, sonic, dielectric, and geochemical tools.

Once the coal component effects have been determined, an interpretation of the logs can be made. This paper will illustrate how to use these corrected logs in a coal evaluation.

AAPG Search and Discovery Article #91010©1991 AAPG Rocky Mountain Section Meeting, Billings, Montana, July 28-31, 1991 (2009)