Integrated Reservoir Characterization of the Entrada Erg-margin Gas Play, Utah: An Outcrop and Seismic Analog for the
North Hill Creek/Flat Rock Field, Southern Uinta Basin, Utah
Thomas H. Morris, Department of Geology, Brigham Young
University, S381 ESC, Provo, UT 84602, phone: (801)378-3761,
[email protected], Will Monn, Department of Geology,
Brigham Young University, S 371 ESC, Provo, UT 84602, John H. McBride,
Department of Geology, Brigham Young University, S 371 ESC, Provo, 84602, and
R. William Keach, II, Landmark and Brigham Young
University, Houston, TX 77042.
Recent discovery of high-BTU gas-charged Jurassic reservoirs
in the North Hill Creek/Flat Rock (NHC/FR) Field, southern Uinta
Basin, Utah, have ignited interest
in below-Tertiary reservoirs within the basin and other areas of Utah. Erg-margin rocks
of the Jurassic Entrada Sandstone are of particular
interest because of their potential to contain large, high quality reservoirs
and develop stratigraphic traps. Entrada
erg-margin sandstones exposed along the east flank of the Waterpocket
Fold, south-central Utah,
appear to be isolated sandstone bodies enveloped within the tidal flat “earthy”
facies. Tidal flat facies
are dominated by mudstones and siltstones. These outcrops are likely analogs for
reservoirs in the NHC/FR Field.
Outcrop and log analyses are integrated with seismic attribute maps of the Entrada section from a 3D seismic survey acquired by Wind
River Resources over the NHC/FR Field. Relative to important reservoir
considerations, our study indicates: 1- eolian-influenced
facies have porosities greater than 23 percent, 2-
water table fluctuations during dune development affect reservoir quality, and
3- erg-margin, reservoir quality sandstone bodies can be offset vertically and
isolated from each other.
Reservoir characterization studies of the outcrop include; photomosaics, identification of facies
and potential baffles and barriers, porosity/permeability analysis, sedimentary
petrology, grain size analysis, and measured sections including scintillometer logs. Strike- and dip-oriented, high
resolution 2D seismic reflection profiles were shot in an attempt to understand
the 3D architecture of