Petroleum System Modeling and its Role in Reducing Uncertainty in the Prediction of Hydrocarbon Types in the Gulf of Mexico
Clara Valdes, Maria L.1; Maldonado-Villalón, Rodrigo; Rodríguez Arvizú, Lázaro; Lara-Rodríguez, Joel; Robles Nolasco, Jose; and Williams Rojas, Carlos
Petroleum systems modeling based on the integration of regional geological information in the Mexican Gulf of Mexico and surrounding basins has allowed the mapping of thermal maturity levels to better define pods of active source rock, determine the timing of initial and peak expulsion of petroleum for each pod, identify migration pathways and predict types and volumes of hydrocarbons.
Oil-prone Tithonian and Oxfordian shales and carbonates constitute the main source rocks, and are widespread in the prospective areas. Reservoirs include Oxfordian sandstones, Kimmeridgian oolites, Cretaceous slopes breccias and Tertiary sandstones. The main reservoirs in deepwater consist of Miocene sands in the south and Eocene-Oligocene in the north, although other plays exist. Combination traps dominate but structural and stratigraphic have also been postulated. Multiple compressional, gravitational and salt related trap-forming events are presente, usually superimposed and with the main phases of deformation at different times in the Tertiary.
Geochemical, structural, stratigraphic, petrophysical, lithological, thermal information and engineering data have been integrated into petroleum system models at various scales and calibrated with well information, including corrected bottom-hole temperatures, vitrinite reflectance, pressures, kerogen type and fluid composition. Results indicate two oil-prone areas, one in the north corresponding to the Salina del Bravo and Perdido Fold Belt provinces, and one in the south and southeastern that includes the Salina del Istmo in deepwater and extends into the Southeastern Basins in shallow waters and onshore. A large, gas-prone area has been defined in the central Gulf where source rocks have been deeply buried. However, basement highs that extend from the westernmost deepwater into shallow water and onshore toward the Tampico-Misantla and southern Burgos basins have kept source rocks at shallower depths and show a transition from a gas to oil prone areas.
These results have allowed a reduction in the uncertainty in prospect evaluation, particularly in relation to the hydrocarbon type expected and a better risk assessment in relation to timing and charge. They have also been a key element to rank prospective areas and focused available budget in order to meet exploration goals.
AAPG Search and Discovery Article #90166©2013 AAPG International Conference & Exhibition, Cartagena, Colombia, 8-11 September 2013