--> Effects of Basin Evolution on Regional Fluid Flow and Temperature History in the Gulf of Mexico, Offshore Louisiana, by R. R. Cornelius, J. E. Huntoon, F-D. Cipriani, and L. M. Cathles; #90986 (1994).

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Abstract: Effects of Basin Evolution on Regional Fluid Flow and Temperature History in the Gulf of Mexico, Offshore Louisiana

Reinold R. Cornelius, Jacqueline E. Huntoon, Francois-Dominique Cipriani, Lawrence M. Cathles

Deep basin processes that occur beneath allochthonous salt can influence temperatures, hydrocarbon maturation, the development of overpressures, and hydrocarbon migration at shallower levels. This is illustrated by a series of Akcess.BasinTM finite element calculations. The calculations are based on 100 mile long regional dip sections from the central Gulf of Mexico, offshore Louisiana.

The burial history for the basin is obtained by backstripping the dip sections under the assumption that salt movement is primarily responsible for the observed variations in the total thickness of stratigraphic units. Areas that experienced rapid sedimentation during a particular time interval are assumed to have been areas of rapid salt withdrawal. Areas where the stratigraphic package is attenuated are assumed to have overlain actively growing salt structures at that time. These assumptions permit the construction of forward models of salt movement upward and basinward from the Miocene to present.

The calculations show that the basinward migration of salt resulted in a regional-scale changes in the temperature field. Where regional salt is thick, deep temperatures are reduced and shallow temperatures increased. The regional temperature anomalies migrate basinward with the salt. Local temperature anomalies associated with salt domes of local mini-basin depocenters are superimposed on the regional changes.

The calculations also show that overpressured fluids can be trapped beneath the Miocene and Pliocene salt sills. When the salt in these sills is evacuated into domes and ridges, the deep overpressured fluids escape. This flow perturbs local temperatures, assists hydrocarbon migration, and connects local reservoirs with more distant hydrocarbon sources.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994