Abstract

This investigation synthesizes the theories of energy transport and gravitational compaction of sediment to develop a deterministic model capable of generating pore-fluid pressure, porosity, and temperature distributions throughout the accumulation of basin sediment. Abnormal pore-fluid pressures develop with increasing rates of sediment accumulation and decreasing hydraulic diffusivity. Sediment temperature distributions depart from typical linear profiles characteristic of steady-state conduction and have increasing rates of sediment accumulation and decreasing hydraulic diffusivity.

A comparison of model output with data from the Gulf of Mexico geosyncline demonstrates that gross fluid pressure, porosity, and temperature distributions are explained by the model. Lateral movement of pore fluid to faults in combination with lithically induced hydraulic and thermal parameter variations explain cases of departure from the general patterns. Sediment in the Gulf of Mexico geosyncline may have been subjected to abnormal pressure since Cretaceous time; sediment presently in the near offshore may now be at its maximum pore-fluid pressure and minimum temperature at any given depth.

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