Abstract: Regional Chronostratigraphic and Depositional Hydrocarbon Trends in Offshore Louisiana State Waters

Chacko J. John, Bobby L. Jones, Brian J. Harder

Successful exploration for hydrocarbons in the Northern Gulf of Mexico basin requires a systematic understanding of hydrocarbon producing trends, sand body geometries and the geologic, engineering and reservoir parameters of the producing sands. This study forms part of the Offshore Atlas project in progress at the University of Texas at Austin, Bureau of Economic Geology, Texas, in co-operation with the U. S. Department of Interior, Minerals Management Service, and the Geological Survey of Alabama, and is aimed at achieving this goal.

In this study, 26 chronozones were grouped into 12 sub-groups. The chronozones were defined on the basis of the benthic foraminiferal biostratigraphic zones and were correlated across the Gulf using well log and seismic data and were projected from the Federal offshore into the State waters. The chronozones on each well log in the 22 cross sections constructed from West Cameron area eastward to the Chandeleur, Breton Sound and Main Pass areas, were subdivided as applicable into four depositional groups consisting of aggradational, progradational, transgressive and submarine fan facies based primarily on SP log shapes.

In the Louisiana State waters there are 86 fields containing 679 reservoirs. This includes 212 oil, 344 gas, 33 condensate and 90 combination type reservoirs. Total combined cumulative production (1975-1995) is 454,335,217 barrels of oil, 114,327,696 barrels of condensate and 5,436,623,888 thousand cubic feet of gas. Total assigned production shows the progradational facies to be most productive yielding 51.69% oil 93.84% condensate, and 77.47% gas. The aggradational facies sands produced 46.96% oil, 1.70% condensate and 17.78%. gas. The submarine fan facies yielded 1.21% oil, 4.45% condensate, and 6.74% gas. Production from the transgressive facies sands was less than 0.2% of the total assigned production of oil, gas and condensate.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas