Victor Hernandez¹, Leonardo Aguilera¹, Ernesto Caballero¹

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

ABSTRACT: Petroleum Systems of the Neogene, Macuspana Basin

The Macuspana Basin is located on the southeast part of Mexico. The gas production mainly comes from a petroleum system of Lower Miocene age. The gas demand in Mexico revitalized the exploration in this region increasing the 3D seismic surveys as well as the regional studies of basin analysis and petroleum systems.

The geologic history of the basin is closely related to the Platform of Yucatan and the Chiapas foldbelt, to the east and south respectively. In their western border, the Platform of Yucatan changes toward the Macuspana Basin, from internal platform carbonates to shaly-prone facies of external platform to basin. Thick shaly-prone packages deposited during the Oligocene and Lower Miocene, in a suboxic marine environment, define the source rock. After the Middle Miocene, an extensional syndepositional tectonic event gives place to the formation of the reservoir rock and traps. A transgressive regional event in the Lower Pliocene deposits the seal rock.

The gas production in 36 fields mainly comes from Upper Miocene and Pliocene sandstone reservoir rocks with porosities varying from 15 to 25%, and permeabilities from 2 to 1700 md, deposited in environments of bars, beach barriers and deltas. The structural style during the Neogene is extensional and characterized by syndepositional listric normal (growth) faults, and shaly-diapirs associated with a detachment surface into underlying mobile substrates of Oligocene geopressured shales. The interaction among faulting, diapirism and sedimentation has given a variety of structural, combined and stratigraphic traps. Nowadays, just the first ones have been partially drilled.

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