--> Origin of Heavy Oil Reservoirs in Mexico: Biodegradation vs. Maturity, by Mario Guzmán-Vega, Lourdes Clara-Valdez, Gustavo Martinez-Pontvianne, Ernesto Caballero-García, Joel Lara-Rodriguez, Laura Villanueva, Luis Medrano-Morales, Jorge Pacheco-Muñoz, Emilio Vázquez-Covarrubias, and Rodrigo Maldonado; #90062 (2007)
[First Hit]

Datapages, Inc.Print this page

Origin of Heavy Oil Reservoirs in Mexico: Biodegradation vs. Maturity

Mario Guzmán-Vega, Lourdes Clara-Valdez, Gustavo Martinez-Pontvianne, Ernesto Caballero-García, Joel Lara-Rodriguez, Previous HitLauraTop Villanueva, Luis Medrano-Morales, Jorge Pacheco-Muñoz, Emilio Vázquez-Covarrubias, and Rodrigo Maldonado
PEMEX

The volume of oil generated from a potential source rock is often estimated in risk analysis. If the quality can also be predicted more precisely, economic forecasts can be more accurate. Discovery of “low” quality crude is certainly less desirable than crude of “higher” value and in some regions can determine economic viability (i.e., deep-water environments). In this paper we summarize current knowledge about the origin of heavy oil reservoirs in Mexico, and the main factors that dictate their composition.

Heavy oils in the Mexican southern side of the Gulf of Mexico are accumulated both offshore and onshore and throughout the different producing regions in Mexico: North, South and Marine regions. Heavy oils can be recognized in most of the different major genetic groups identified in the Mexican Gulf Coast Basin by means of geochemical and isotopic criteria. The principal geochemical/geological processes that have determining the origin of heavy oils in the Mexican reservoirs were: 1) source rock type, 2) early expulsion, and 3) biodegradation.

Nevertheless than the biodegradation is the dominant process related to the origin of heavy oils in the North and South Regions, the main factor induced low gravities in the offshore heavy oils in the Marine region is related to an early expulsion of the oil from a marine marl-dominated source rock. However, taking in account that in deep water environments are expected low thermal gradients and shallow exploration targets which are ideal conditions for microbial degradation of crude oil, there are high possibilities to find biodegraded oils reservoirs in deep water prospects. So, it is very important to incorporate into the deepwater exploration workflow in the Mexican prospects conceptual models of biodegradation in a consistent and quantitative way and to link these to up-to-date basin modeling software to more accurate fluid-property predictions.

AAPG Search and Discovery Article #90062©2006 AAPG Hedberg Research Conference, Veracruz, Mexico