Providence Resources - Over pressure - A variety of processes have...

A variety of processes have been proposed for the generation of overpressure; the most commonly quoted are porosity reduction due to compactional disequilibrium or lateral stresses, and fluid expansion. In the latter case, the excess fluid associated with hydrocarbon generation is considered to be a major contributor to overpressure generation, particularly at depths greater than 12,000 ft.4
While it is probable that overpressure is the result of a number of processes, it is important to recognize the dominant mechanism. The dominant process may change both in spatial and temporal position within the basin, and it is critical to recognize which process is currently active, as this may influence the interpretation of the hydrocarbon potential of a basin.

Prospect risking
Exploration prospect risking is quantified by multiplication of the risking factors: trap, seal, hydrocarbon generation and timing, and migration. 5
In an overpressured basin there are implications for the estimation of all of these factors with the exception of the trapping mechanism.
Seal
Every overpressured system has a seal. There is always a top seal, which in overpressured terms is the transition zone.
Side seals can be present, either as a result of faults, facies variations, or diagenetic alterations. The side seal may not be recognizable from seismic sections, but is most often inferred from lateral pressure variations.
The significance of the pressure seals in abnormally pressured compartments is that stacked reservoirs may be present. Thus each pressure compartment has the potential for hydrocarbon trapping, and a number of plays may be stacked vertically on top of each other.