--> ABSTRACT: Origin, Detection, and Evaluation of Abnormally High Formation Pressures, by Walter H. Fertl and George V. Chilingar; #91038 (2010)

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Origin, Detection, and Evaluation of Abnormally High Formation Pressures

Walter H. Fertl, George V. Chilingar

Abnormally high pore fluid pressures exist worldwide in formations ranging in age from Pleistocene to Cambrian. These pressures may occur as shallow as a few hundred feet below the surface or at depths exceeding 20,000 ft. High pore fluid pressures may appear in shale-sand sequences or in massive carbonate-evaporite sections.

Detecting and quantitatively evaluating overpressured formations are critical factors for exploring, drilling, and producing operations. Also considered are the techniques for detecting drilling and well log overpressure and the parameters affecting pressure evaluation methods for practical formations.

Discussions center on the latest results of pulsed neutron capture (PNC) logging devices [which measure the macroscopic cross section Sigma (^Sgr) for thermal neutron capture] and the possibility that montmorillonite converting to illite may cause overpressure.

Additional discussions include the origin of abnormal formation pressures, ideas on overpressures encountered in carbonates, and economic factors to consider in exploring overpressured environments.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.