The use of standard core-drilling methods to evaluate commercial possibilities of deep Pennsylvanian coals in southwestern Indiana is difficult if not prohibitively expensive owing to complex faulting and the presence of numerous alluvial channels.

In Posey County, where complex faulting is common, more than 5,000 oil tests have been drilled, most having electric logs or other geophysical logs run more than 20 years ago. Correlation of these logs with nearby coal-test cores, lithologic strip logs of well cuttings, and sparse outcrop information has resulted in: (1) mapping of zones of closely spaced normal faults (as many as four individual faults in a single well) with vertical displacements of 20 to more than 300 ft (6.1 to > 91.4 m) and horizontal lengths of as much as 20 mi (32 km); (2) rapid mapping of coal thicknesses to an accuracy of about 1 ft from old geophysical logs; (3) delimiting of channels that are contemporaneous with peat deposition (related to thickness and sulfur content of coals); and (4) correlating for he first time several lithologic units in rocks of Pennsylvanian age. Through study of modern mining techniques in an area of closely spaced drilling in Indiana and Illinois we are able to consider the potential for underground mining in highly drilled areas of old petroleum production. Data integration from these diverse sources facilitates rapid outlining of prospective areas of minable deep coals that would not be possible otherwise.

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