AAPG Annual Convention and Exhibition

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Mexican Frontier Hydrocarbon Basins

Abstract

While current interest in Mexico is focusing on sales for blocks offshore Gulf of Mexico and in adjoining onshore productive basins, now is the time for explorationists to turn their attention to the frontier basins where, after a few more bid rounds in the oil producing areas, there will likely be calls for nominations leading to awarding of exploration contracts. This paper summarizes the present state of evaluation and ranking of these under-explored areas in preparation for such future bid rounds. First of all, it is important to realize that these are not entirely virgin basins. Since the 1940s, Pemex geologists have undertaken extensive field mapping of the whole country and identified potential source and reservoir quality rocks in a number of localities. Magnetic surveys identified deep basins and seismic surveys picked out structural prospects. Some wells were drilled which often resulted in oil or gas shows. Success however has been very limited, with commercial production being established only in the Sabinas Basin. We will review the findings in all the other frontier basins in the hope that a few basins will be found to be productive in the future. Cenozoic Pacific margin type basins lack a good Monterrey-type source rock; only gas shows have been encountered so far. Paleozoic back-arc basins on Mexico's High Plateau have had their source rocks burnt out and traps breached by the Laramide orogeny. Mesozoic Basins have been similarly inverted except for the extension into Mexico of the Peten Basin. Accreted prisms of sediment on the western margin have not been encouraging. The Yucatan Platform remains stable and immature, but has curious gas shows in the area of a major meteoric impact crater. In general, all these areas have low probabilities of encountering commercial hydrocarbons. For this reason Pemex has abandoned further investment in them. But all of the above conclusions are based on limited information. These frontier areas are ripe for re-examination and renewed thinking, especially applying up-to-date geological concepts and production technologies. Maybe some of them will merit being nominated for future bid rounds. Maybe one or two will find commercial hydrocarbons