Geophysical logging has become an important phase of coal exploration. Electric logs that were run in wells drilled for oil and gas can be used to make preliminary studies of structure, coal thickness, depth, and sedimentological anomalies that affect coal continuity. They can be used to locate the best areas for local exploration coring.

Radioactivity logging has become standard procedure in most areas in exploration drilling and coring programs. Thickness (and therefore tops and bottoms of seams) can be determined with great precision on density and neutron logs. Interpretation of radioactivity logs allows the predictions of local geological, structural, stratigraphic, and sedimentological anomalies that will influence mining programs. Ash content calculations which compares favorably with core analyses can be made with the use of density logs. With the use of sonic logs in conjunction with density logs, calculations can be made which will give an indication to the strength of roof and floor rocks.

This paper presents case studies of the successful use of geophysical logs in regional and local phases of exploration and the discrimination of coal seams in several geographic locations.

End_of_Article - Last_Page 526------------