Ryan Birkenfeld¹, Zuhair Al-Shaieb², James Puckette², Phebe Deyhim², Amy Close²

(1) Oklahoma State University and ExxonMobil, Stillwater, OK
(2) Oklahoma State University, Stillwater, OK

ABSTRACT: Sequence Stratigraphy as a Major Control of Depositional Facies of the Vicksburg Formation in the South Texas Gulf Coast Area

The sequence stratigraphic framework of the Vicksburg Formation was developed using 3-D seismic data integrated with facies derived from core, core calibrated logs and ichnofaunal data. The Vicksburg strata were deposited in a high accomodation depositional setting that was directly related to the variable rate of syndepositional listric normal fault movement and eustatic sea level fluctuations. This depositional setting has influenced the types and quality of Vicksburg reservoirs. The Vicksburg Formation can be characterized as a super sequence bounded by the Eocene Jackson Shale at its base and the Oligocene Frio Formation at its top. The Lower Vicksburg strata are an aggradational lowstand systems tract composed of repetitive depositional patterns of paralic facies. Each sequence is characterized as being deltaic in origin and composed of prodelta sediments that grade vertically into sand-rich channel-fill deposits. These composite sequences are repeated as accomodation space and sediment supply remained relatively constant. The Middle Vicksburg interval is a retrogradational transgressive systems tract. This interval is composed of interbedded sandstones and shales of high order sequences that were deposited when accommodation space exceeded sediment supply. This increase in accomodation space can be resolved seismically as an expansion of section within the systems tract. The Upper Vicksburg is the highstand systems tract. It contains progradational paralic facies that grade vertically into channel-fill sandstones with associated interfluve deposits. These parasequence sets are seismically resolved as high amplitude continuous reflectors that are repeated with continued progradation. Lithofacies are directly related to the position of sea level and spatial proximity to major faults.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado