Print this pageAbstract: Regional Pressure Environments and Petroleum Accumulation
Four pressure environments are especially favorable for oil and gas: (1) normal below abnormal; (2) deep top of abnormal pressures; (3) base of normal pressures; and (4) abnormal pressures between transition and overburden. The first three environments are widespread and have normally pressured analogs. Concentration of petroleum in these environments of relatively low fluid potential is explained by conventional hydrodynamics. The fourth environment, known only from the Gulf Coast is limited to abnormally pressured beds. The top of this zone also can be explained in hydrodynamic terms. Its base appears related more closely to the properties and processes associated with beds under low effective stress.
Understanding these environments, an explorationist can define prospective areas, depths, formations, trap types, and probable petroleum composition. Exploration for these environments in normally pressured areas uses ground-water data and subsurface pressures to construct potentiometric maps and cross sections. Cross-formational fluid relations are evaluated by mapping differences in potentiometric surface between successive beds. Where abnormal pressures are present, well logs and seismic data also may be used to construct maps and cross sections showing the geometry and magnitude of the pressure systems in the area.
AAPG Search and Discovery Article #90971©1976 AAPG-SEPM Rocky Mountain Sections 25th Annual Meeting, Billings, Montana