Gas Province in the Deepwater Southern Gulf of Mexico

摘要

Since 2006, PEMEX drilled nine wells to test Tertiary targets in the south of Gulf of Mexico, in water depths between 800 and 1920 m, resulting in the discovery of five gas fields in the Miocene turbidite plays, with reserves varying between 120 to 900 billion cubic ft. The traps are located over N-S and NE-SW structural alignments belonging to the Mexican Ridges and Catemaco Fold Belt provinces respectively, which formed by contraction due to gravitational sliding during upper Miocene and Pliocene. Integrated analysis of special seismic processes and attributes, logs, core analysis and paleontology confirmed a sedimentary model of submarine channels and fans in the toe of slope and basin; however, up to now the discoveries correspond to channels and overbank facies, varying in sinuosity, and with transport direction N to NE. Although the great thickness of sandy sequences (up to 300 m), the reservoir rock is laminated and complex. Sandstones and siltstones with quartz, potassium feldspar, and volcanic components show vertical and horizontal heterogeneity due to changes in grain size, sorting, and presence of laminated, dispersed, and structural clay; this condition reduces reservoir quality, but still, in channels porosity varies between 15-22% and maximum permeability reaches 250 millidarcies, impacting the daily production rates and volumetric evaluation. The current exploratory strategy is focused to deeper and farther prospects, in water depths above 2000 m, where the model suggests a prevalence of submarine fan facies for Miocene and Oligocene plays, with better reservoir rocks. The prospective resource of this province exceeds by far 10 trillion cubic ft of gas.