f Regional Source Rock Maturity and Petroleum Play Overview of the Deep-Water Yucatan Margin, Southern Gulf of Mexico

The deep-water Yucatan margin remains one of the most underexplored areas of the Gulf of Mexico and due to a lack of well penetrations and systematic mapping, one of the least understood. Widespread oil slicks can be observed near salt structures positioned along the continent-ocean boundary, yet the maturity and distribution of hydrocarbon kitchen areas remains poorly constrained. In this study we use a grid of 2D post-stack depth migration (PSDM) seismic profiles tied to DSDP wells to map and analyze the stratigraphy, structure, and thermal maturity of potential source rock intervals across an area of >120,000 km². Six pseudo wells were positioned along dip and incorporate estimates of lithology, lithospheric thickness, and lithospheric heat-flow to help constrain a 3D maturity model based on regional mapping key intervals using the seismic data.

Integrated model results suggest that the primary Tithonian-age source rock interval reached oil maturity in the diapiric salt province near the continent-ocean boundary during the Oligo-Miocene. Inherent model uncertainty from lack of direct well penetration data in the local area was addressed by using analog well data, seismic observations, and by modeling multiple possible thermal scenarios. These alternate model scenarios were combined to create maturity risk maps for the area. Results suggest that the deeply buried, salt-involved minibasins along the outer marginal trough are low-risk and the upper slope high-risk for hydrocarbon generation and migration. Large, salt-related structural traps are located directly adjacent to oil kitchen areas within the deeply buried minibasins and require only vertical migration to charge. Normal faults bounding the salt minibasins provide possible migration pathways directly into the overlying salt-related structures, evidence for which is provided by clustering of oil slicks at the sea surface overlying these trends. To the southeast, gravitational sliding and collapse formed a series of salt-roller structures containing potential Norphlet equivalent reservoirs into which hydrocarbons may have migrated laterally up-dip from the deeper kitchen areas. Another potential play type includes Triassic-Jurassic rift structures in the sub-salt section; however, the analysis suggests that any potential reservoirs in this section would likely require a pre-Late Jurassic source rock to provide charge and would be associated with a higher risk of over maturity.