Abstract: Sequence Stratigraphic Setting of Neogene Turbidite Systems, Green Canyon and Ewing Bank, Northern Gulf of Mexico: Preliminary Results

Paul Weimer, Peter Varnai, Alonso Navarro, Zurilma Acosta, Fadjar Budhijanto, Rafael Martinez, Tomas Villamil, Mark Rowan, Barry McBride

The Neogene strata of Green Canyon and Ewing Bank lease areas in northern Gulf of Mexico are a major exploration play. Most discoveries and future exploration targets are in Neogene turbidite systems (lowstand systems tracts). The regional sequence stratigraphy for this area has been interpreted to help define the potential areas for future exploration. Data base consists of 10,000 km of multifold seismic data, well log data for 100 wells, biostratigraphy from 180 wells.

Thirteen depositional sequences have been identified in the late Miocene to Pleistocene strata, and are interpreted to correspond to major eustatic drops in sea level (5.5, 4.2, 3.8, 3.0, 2.6, 2.4, 1.9, 1.4, 1.1, 0.8, 0.7, 0.5, 0.4 Ma). Paleoecology indicates that the area was in bathyal water depths throughout the late Miocene to late Pleistocene. Structural restorations indicate that the area consisted of several shallow salt sheets prior to 5.5 Ma. Individual salt-withdrawal basins bounded by diapirs and growth faults developed as the area was loaded with sediment.

Existing fields and sand bodies are characterized within a sequence stratigraphic framework. Major sand-prone intervals directly overlie the 3.8, 3.4, 1.9, 1.4, 1.1, and 0.8 Ma sequence boundaries. A stacked condensed section occurs in the area between 3.0 to 1.9 Ma; it separates the stratigraphy into two discrete sections. Few reservoir intervals develop in this interval, because of a lack of major sand source into the basin. In general, sediments below the major condensed section were considerably sandier than those sequences younger than the condensed section. Producing sands are from turbidite systems deposited in mid-bathyal water depths in the GC 205, 184 (Jolliet) 65 (Bullwinkle), Ewing Bank 826. Reservoirs vary from massive, blocky sands to thinly laminated sands with low resi tivity, and are commonly associated with seismic amplitude anomalies.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994