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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 7. (July)

First Page: 1360

Last Page: 1360

Title: No Title Provided: ABSTRACT

Author(s): Mark W. Hodson, John M. Sharp, Jr.


Rocks, particularly those formed from clayey sediments, are capable of retaining pore fluids at pressures greater than hydrostatic. Such pressures are frequently encountered while drilling for oil and gas, and consequently the phenomenon of excess fluid pressure has been studied extensively. Anomalous temperature changes with depth have been observed associated with overpressured zones and these anomalies have themselves been the object of considerable thought. However, few studies have attempted to model simultaneously the generation of overpressuring and the associated temperature patterns. Such a model has been constructed, with an equation describing one-dimensional flow through a porous medium at its heart. Through a computer program, this equation describes the vert cal movement of fluids and heat through accumulating sediments and the resultant densities, pressures, and temperatures. This program was applied to an accumulating thickness of "mud" and sand approximating a generalized Gulf Coast section. The resultant plots of pore pressure, porosity, and temperature versus depth are similar to those typifying the drilled areas of the Gulf Coast. These characteristic profiles can be viewed as a consequence of the Gulf Coast overpressured environment.

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