Regional Characterization of Pressure Gradients Spanning the Onshore and Offshore Gulf of Mexico Basin

Comprehensive regional characterizations of subsurface geopressure gradients are publically unavailable for the Gulf of Mexico basin, which is the most important petroleum-producing region in the United States. Understanding the occurrence, distribution, depth, and magnitude of subsurface pressure gradients, depressurization zones, and overpressured regions is critical for evaluating areas with potential pressure-related production and geohazard issues, and for minimizing the environmental consequences of petroleum production in the United States.

The U.S. Geological Survey has created a series of regional geopressure gradient maps that characterize the depth and distribution of isopressure gradient surfaces spanning the onshore and offshore portions of the Gulf of Mexico basin, including Texas, Louisiana, Arkansas, Mississippi, Alabama, Florida, and the associated offshore State and Federal waters. This mapping series includes 10 maps, 5 of which display the magnitude of the pressure gradient surfaces from 0.60 psi/ft to 1.00 psi/ft, and 5 corresponding maps that show the density of the data distribution. Geophysical logging and drilling data from more than 100,000 wells were used for this regional study.

This map series provides foreknowledge of oil and gas production issues as well as overpressured geohazards in the near surface as well as in the deeper subsurface, which is critical for the safety and mitigation of pressure-related geohazards related to the new and ongoing exploration and development of the Nation’s petroleum energy resources. In addition, these pressure maps enable the identification and quantification of anomously overpressured regions, which are necessary for the exploration of deep oil and gas resources based on their distinct pressure signatures. Regional subsurface pressure characterization is essential for the evaluation of reservoir-seal integrity for evaluation of potential undiscovered hydrocarbon accumulations. The identification of overpressured or underpressured regions is also a critical parameter for evaluating the viability of geological sequestration and storage containment of fluids, such as supercritical carbon dioxide for alternative disposal methods of waste greenhouse gases.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California