Jurassic Eolian Depositional Systems of the Northern and Southern Gulf of Mexico Compared: Implications for New Exploration and Development

Abstract

Abstract

Jurassic eolian reservoirs have yielded large discoveries and currently produce hydrocarbons in both the Northern Gulf of Mexico (USA) and Southern Gulf of Mexico (Mexico). Yet these reservoirs have received considerably less attention than deep-water systems in both areas. Analysis of seismic data, well logs, biostratigraphy, and whole core provide insights in to reservoir characteristics while plate tectonic and salt tectonic reconstructions allow a better understanding of the paleogeographic controls on regional distributions in both Mexico and USA offshore exploration areas.

In the northern Gulf, Oxfordian-age Norphlet reservoir system is largely contained within a large-scale erg (dryland sand sea). Reconstruction of the Norphlet erg here system was challenging from several perspectives. First, the Gulf Basin configuration needed to be restored to original position prior to sea floor spreading and the 30-degree counterclockwise rotation of Yucatan that occurred after Norphlet and Smackover deposition. Second, post-Oxfordian rafting of the Norphlet in deep-water areas was corrected for by restoring structural gaps mapped from modern 2D and 3D seismic data. The resulting paleogeography depicts a large eolian erg (58,000 square km) concentrated on the eastern side of the basin in low paleolatitudes where many modern erg systems are formed. Convergence of northerly and easterly winds transporting sand from exposed Appalachian and Suwannee basement terranes allowed concentration of eolian reservoirs in several areas including Mobile Bay, Destin Dome, and the Appomattox find near present-day Desoto Canyon. In the northern Gulf, exploration discoveries are generally hosted by eolian dune sandstones including barchans and barchanoid types, while fluvial-wadi reservoirs are less prospective.

In Mexico offshore areas, Oxfordian-age eolian dune deposits are present within Mexico's Ek-Balam field area but these are interpreted as small coastal systems in contrast to the major sand sea (erg) in the USA. Available formation microscanner data shows angle of repose (25 degrees +/-) dune bedding oriented toward the east. This probably reflects late-stage onshore winds, as the primary clastic source is the exposed basement of the Yucatan Platform located to the west.

New drilling results from the Norphlet deep-water play of the northern Gulf can be applied to new exploration in the southern Gulf, with the opening of Mexico to international exploration.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016