Abstract: Source Rock Systems of Northeast Mexico

Linda D. Raedeke, Noel Holguin-Quinones, Richard C. Haack, Genaro Ziga-Rodriguez, Jeremy E. Dahl

Four source rock systems were identified in the Chihuahua, Sabinas and Burgos basins of northeast Mexico.

The Upper Jurassic La Casita Formation is the best source in the Chihuahua and Sabinas basins. The marine shales are thick and relatively rich in organic matter, particularly in the basin centers. Although generally highly mature, or overmature (dry gas), in the basin centers, the section is less mature on the southwestern flanks. Biomarkers from Chihuahua indicate it is the probable source for oil shows near the less mature flank.

The Aptian La Pena Formation is rich but thin in Chihuahua and Sabinas. The minimal hydrocarbon charge is restricted to the basin centers where maturities are in the gas window. In both basins kerogen was spent and generation ceased from upper Jurassic and Aptian systems by early Tertiary time.

The Turonian Ojinaga (Chihuahua) and Eagle Ford Formations (Sabinas) have moderate hydrocarbon potential, with uniformly good quantities of source kerogen over thick sections. Uplift arrested generation at about 40 ma.

In the Burgos basin, the Mesozoic systems have moderate to poor organic richness in the southernmost and northernmost parts of the basin; biomarker data indicate they are not important sources.

The Tertiary section is the source for gas and condensate in the Burgos basin as indicated by biomarker and geologic data. The section with "best" potential is the Paleocene-Eocene Midway-Wilcox, but indirect evidence indicates that successively younger formations are the source for hydrocarbons toward the east. The limited Tertiary section in the Chihuahua and Sabinas basins is not a source.

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