Maria de Lourdes Clara¹, Hugo Martinez¹, Jaime Gonzalez¹

(1) Pemex Exploracion y Produccion, Villahermosa, Tabasco, Mexico

ABSTRACT: Petroleum Geology of the Chiapas-Tabasco Area

The integration of geochemical, geological, geophysical and sedimentological data is important for understanding the generation, migration, trapping and timing of the petroleum systems in the Chiapas-Tabasco area. The main petroleum system is the Tithonian-Cretaceous (!). The source rocks are carbonates shaly-prone containing type-II organic richness (15-45% MOD). The d13C values range from -25.6 to -27.9 o/oo, and the biomarkers indicate an anoxic marine carbonate environment which is characterized by C29/C30 > 1, C35/34 >> 1, Ts/Tm < 1, and low abundance of diasteranes. The expulsed oils range from 20 to 50 API, with sulfur content from 0.15 to 3.09% depending on the thermal maturity.

The most important play is the Cretaceous, which is characterized by carbonates of platform, talus and basin, with matrix porosity from 2 to 8%. Some diagenetic changes such as the dolomitization and fracturing favor the accumulation of petroleum.

The hydrocarbons accumulated from Late Cretaceous to Lower Miocene in structural traps oriented NW-SE, caused by compression stress during the displacement of the Chortis Block in S-SE direction. Other traps are related to diapiric, gravitational and compactional processes associated with extensional stress. The high volume of siliciclastic sediments causes the development of growth faulting and roll-over structures, oriented NE-SW, during the Neogene.

This area has an excellent timing between the elements of the petroleum system. The source rocks expulsed petroleum from the Late Miocene to Pleistocene being the vertical migration pathways related to the faulting zones.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado