Abstract

Numerous petroleum seeps and chemosynthetic communities are present on the continental slope in the northern Gulf of Mexico. These features are associated with faults and salt highs and indicate recent petroleum migration.

Thirty-three known petroleum seep and/or chemosynthetic communities in Green Canyon and Ewing Bank were studied in a sub-regional context to understand their stratigraphic and structural controls and their significance to the overall petroleum system. Results indicate that surface seeps occur associated with all different allochthonous salt systems present (ramp-fault systems, roho-systems, stepped-counterregional systems, and counterregional systems), and all four systems are efficient. Of the thirty-five fields and discoveries in the area, only six occur near (<4.8 km) seeps, suggesting that the seeps are indicative of an efficient and mature petroleum system, but not necessarily of proximal reservoirs. Petroleum seeps may be more related to poor trap and/or seal development. The relative rates of vertical migration of petroleum can be estimated based on the timing of salt weld formation. These estimates range from 0.0015 to 0.025 m/y.