Abstract: Abnormal High Pressure and Environment of Deposition

By

Gene B. Martin

An apparent relationship of the environment of deposition to the occurrence of abnormal high fluid pressures in a sand-shale sequence of the subsurface South Texas Oligocene is established. The abnormal high pressures are generally encountered in the "downdip" facies which consists of deltaic sediments of alternating inner neritic (includes brackish and near-shore marine) and middle neritic (shallow marine) depositional environments.

There is an abrupt change in the environment of deposition that seems to coincide with the top of the abnormal high pressure zone.

This new approach to predicting abnormal high pressured formations can be used at the well-site.

The key to a better understanding of the problems and the solution to these problems associated with abnormal high fluid pressures may be found in an understanding of the depositional environments and history of the sedimentary basin. In order to accomplish this, there may be a need for more workers to examine surface and subsurface rock samples.

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