Sulfur Exploration with Core-hole and Surface Gravity
M. Alexander, K. O. Heintz, 1998. "Sulfur Exploration with Core-hole and Surface Gravity", Geologic Applications of Gravity and Magnetics: Case Histories, Richard I. Gibson, Patrick S. Millegan
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Announcement of a major discovery near Orla, Texas, in 1968 set off an extensive sulfur exploration play in the Permian Basin. The terrane, geologic setting, and mode of sulfur deposition were favorable for use of the gravity exploration method, and it became the most widely used and cost-effective geophysical technique for the play. Prospects commonly were located through use of reconnaissance coverage, then detailed gravity surveys were conducted to delineate the most favorable sites for initial core drilling.
An important procedure in the exploration program designed by Exxon Co. USA was the analysis of prospective gravity anomalies through model studies, using measured subsurface densities for control. Exxon Production Research Company developed a modified borehole gravimeter which successfully metered twenty-eight core holes. Densities calculated from the core-hole gravity were judged to be more accurate and consistent than those derived from other sources.
The core-hole gravimeter was a technical success. Whether continued use might have led to a commercial discovery is uncertain. An abrupt plunge in sulfur prices on the world market ended Exxon’s exploration play before several promising anomalies were evaluated fully.