Geologic Controls on Petroleum Seeps in Mississippi Canyon and Northern Atwater Valley Areas, Northern Deep Gulf of Mexico: Implications for Petroleum Migration

Paul Weimer, Todd Lapinski, Renaud Bouroullec, Veit Matt, and John Martin
University of Colorado, Boulder, Colorado

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.

Sixty-seven known petroleum seep and/or chemosynthetic communities were studied in the Mississippi Canyon and Atwater Valley protraction areas in a subregional context. The objective was to understand the stratigraphic and structural setting and its significance to the migration, and accumulation of petroleum.

Results indicate that surface seeps occur associated with all different allochthonous salt systems present (roho, stepped- counterregional, salt-cored foldbelt, and basement-controlled diapirs), and all four systems are equally efficient at migrating petroleum to the surface. Of the fifty fields/discoveries in the area, only six occur near seeps, within less than 4.8kilometers, suggesting that the seeps are indicative of an efficient and mature petroleum system, but not necessarily of proximal reservoirs, due potentially 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, and/or regional petroleum systems modeling. These estimates range from 0.0015 to 0.025 meters per year.

AAPG Search and Discovery Article #90032©2004 GCAGS 54th Annual Convention, San Antonio, Texas, October 10-12, 2004