Pre-salt Lacustrine Petroleum System, Onshore Mexico

Abstract

A petroleum system in carbonates lying beneath evaporites in a Jurassic graben in the Tampico-Misantla Basin is an analog for applying to the interpretation of pre-salt seismic sequences in grabens elsewhere in the Circum-Gulf of Mexico. The graben, which is about 40 km wide and known to be at least 60 kms long, lies to the west of the Tuxpan Platform, near the town of Poza Rica, Veracruz State. It is largely filled with marine shales and limestones, in which ammonites as old has Upper Bathonian have been identified from cores (Cantu 1979). The petroleum system was discovered by PEMEX at the Huehuetepec oilfield in 1969 (Gonzalez 1970). The reservoir is known from a few wells in the area to be a partially dolomitized limestone up to 30 meters thick. The sequence contains oolitic, bioclastic and pelletoid grainstones and argillaceous micrites and wackestones. Fossils include small gastropods, pelecypods, arenaceous foraminifera, ostracods, arthropod pellets and calcareous algae. The carbonate is interpreted to have been deposited in a saline lacustrine to restricted marine environment. Although remaining reserves are estimated to be only 4.6 million barrels of oil equivalent and have not been further developed, this old discovery is significant as an analog for future pre-salt exploration.

AAPG Datapages/Search and Discovery Article #90369 © 2020 AAPG Hedberg Conference, Geology and Hydrocarbon Potential of the Circum-Gulf of Mexico Pre-salt Section, Mexico City, Mexico, February 4-6, 2020