Geothermal patterns and petroleum traps, Louisiana

Published literature documents varying degrees of correlation between geologic structures and geothermal highs (halos) of several petroleum fields. In conjunction with these fields, additional structures and associated productive trends have been evaluated in order to develop certain predictive criteria. The studies attempted in this regard include structural and stratigraphic traps, rollover anticlines, and salt domes with productive horizons of various ages in Louisiana. As part of the characterization of the subsurface temperature regime of the regions studied, the following broad generalizations seem to be in order. (1) Geothermal halos observed near faults appear astride the fault, or clearly confined to one fault block or the other. (2) A single geothermal halo in a deep section may be overlain by multiple halos, generally of lower relief, in shallow sections. (3) Geothermal halos associated with deep-seated salt domes are located in the sedimentary section on or near the top of the dome, near the perimeter or on the flanks. Such halos are not discernible on shallow domes. (4) In the interior basin, a salt dome with productive horizons appears to have a geothermal halo of higher relief than those in the vicinity with no petroleum accumulations. (5) Even some petroleum traps, created by sedimentary facies changes with no distinct structural closures, are marked with geothermal halos. The observed characteristics of the subsurface thermal regimes are generally explicable in terms of thermal properties of rocks and pore fluids and by hydrodynamics.