--> --> ABSTRACT: Maturation and Migration History of the HC Systems of S. Texas, by Felipe A. Pontigo Jr., Theresa F. Schwarzer; #91020 (1995).
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Previous HitMaturationNext Hit and Migration History of the HC Systems of S. Texas

Felipe A. Pontigo Jr., Theresa F. Schwarzer

Integrated modeling of hydrocarbon generation, migration, and trap emplacement for the South Texas. King Ranch area suggest that most of the hydrocarbons were emplaced about 28 MY ago. The rapid accumulation of the prograding Frio sediments over the 30 MY sea level lowstand triggered maximum fault movement, maximum structural closure development and maximum paleopressures. The major listric growth faults for the Frio system detached in the Vicksburg Formation. These faults then acted as the conduits for the vertical migration of hydrocarbons from the lower Tertiary source rocks which were at peak Previous HitmaturationTop. Continued deposition of the Tertiary section over these sediments and the development of geopressures resulted in the redistribution of the originally emplaced hydroc rbons into their present day traps.

Modeling of pressure controls is interpreted to indicate that paleopressures may have been a major factor in the emplacement and redistribution of hydrocarbons. The association of a rapidly accumulating sedimentary system coinciding with an actively moving fault system enabled the vertical migration of hydrocarbons from the source beds into younger sediments. The hydrocarbons were first trapped in the transition zone between over pressured and normally pressured sediments. Continued burial of the sedimentary section by the prograding system, and the large amounts of sediments deposited caused a significant increase in the geopressure gradient, which in turn resulted in the redistribution of hydrocarbons into younger and lower pressure traps as pressure gradients were created and chang d through time.

The South Texas, King Ranch area is located in the Tertiary Rio Grande Embayment which covers a large portion of south Texas and includes the Burgos Basin of Mexico. The embayment is bounded to the east by the San Marcos Arch, to the north and west by the updip limits of Tertiary deposition and in Mexico by the Tamaulipas Arch. It covers approximately 90,000 Km2 onshore and extends offshore to the Perdido Fold Belt.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995