Seismic Sedimentological Expression of Higher-Order Lowstand Slope Fans and Prograding Deltas in the Frio Formation, Corpus Christi Bay, Texas

Hongliu Zeng and Robert G. Loucks
Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin,
10100 Burnet Rd., Austin, Texas 78758

An integrated study of well and seismic data based on seismic sedimentological principles was performed to map fourth- and fifth-order systems tracts in Oligocene (Frio) strata in the Corpus Christi region of South Texas. At least 16 higher-order (fourth- and fifth-order) sequences were identified using wireline logs and mapped using seismic amplitude stratal slices. Higher-order lowstand slope fans are best characterized by submarine channel/levee systems and by fan-shaped sand-body geometry. Higher-order lowstand prograding deltaic systems are composed of strike-oriented, lobate deltaic sand bodies. Distribution pattern of sandstone reservoirs is controlled primarily by accommodation resulting from rollover topography associated with growth faulting. Strike-oriented sandstone bodies were deposited between the boundary fault and the hingeline atop rollover structures. Dip-oriented sandstone bodies were distributed within the submarine channel/incised valley and beyond the hingeline into the distal basin. The higher-order slope fan and prograding deltaic systems are highly cyclic through geologic time. Thin-layered, multiple sandstone gas pays are expected in and around domal (rollover) structures.

AAPG Search and Discover Article #90069©2007 GCAGS 57th Annual Convention, Corpus Christi, Texas