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Rucsandra M. Corbeanu1, Michael C. Wizevich1, Xiaoxian Zeng1, George A. Mcmechan1, Janok P. Bhattacharya1, Stephen H. Snelgrove2, Craig B. Forster2
(1) University of Texas at Dallas, Richardson, TX
(2) University of Utah, Salt Lake City, UT

Abstract: 3-D internal geometry of delta plain channel deposits, Cretaceous Ferron Sandstone, Utah

3D reconstructions of reservoir architecture using outcrop analogs are hampered by limited exposure of mostly 2D outcrops. In this study, we integrate outcrop photomosaics, measured sections, permeability measurements and 100MHz 2D and 3D Ground-Penetrating Radar grids, tied to well data. This allows us to fully document the 3D facies architecture of stacked delta plain channel deposits from the Cretaceous Ferron delta complex in Utah.

Four erosively-based channel deposits (CD) were mapped on photomosaics. The lowermost channel deposits (CD1) overlie rooted and burrowed coal-rich, delta-plain mudstones and comprise trough cross-bedded sandstone with rare burrowed siltstone drapes. CD2 consists of meter-thick, laterally-accreting cross-bedded sandstone beds, floored by mudstone intraclast conglomerate. The sandstone beds are draped with mudstones that contain rare burrows, indicating periodic marine incursion within an accreting point bar. CD3 locally erodes into CD1 and CD2 and consists of massive and large-scale trough cross-bedded sandstone with thick mudstone intraclast conglomerates. CD4 lies at the top of the outcrop and comprises medium-grained cross-bedded to convolute stratified sandstone. The channel deposits are characterized by specific radar facies and permeability structures. The most important flow barriers in the system are interpreted to be the mudstone intraclast conglomerate along basal scours and the mudstone drapes at the top of inclined beds within CD2. The spatial continuity and variation of these flow barriers was determined by direct mapping in conjunction with modeling 3-D experimental variograms of the GPR amplitudes in each radar facies.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana