Ben W. Crouch1,
Michael L. Hackney1,
Bill J. Johnson2
(1) Petroglyph Energy Inc, Hutchinson, KS
(2) Halliburton Energy Services Inc, Pratt, KS
Abstract: Sequence stratigraphy and reservoir character of lacustrine carbonates in the Basal Limestone Member: Lower Green River formation (Eocene), Duchesne and Antelope Creek Fields, Duchesne Co., Utah
Recent exploration and development of oil and gas reserves of the lower Green River Formation in Duchesne and Antelope Creek fields provide new perspective on the detailed stratigraphic framework and reservoir potential of the Basal Limestone Member. Internal framework of the Basal Limestone Member is composed of seven parasequences which record pulses of shoreline retrogradation and lake-level deepening during the first transgressive event of the lower Green River Formation. This parasequence set is bound at its base by a major flooding surface and sequence boundary, which conformably separate these deposits from Colton/Wasatch formations. The top of the parasequence set is bound by a maximum lake-flooding surface, separating it from progradational parasequences of the basal Castle Peak Member. The Basal Limestone parasequence set ranges from 54 to 60 meters (180-200 feet) thick and is composed of lacustrine micritic limestone, dolomicrite, and calcareous mudrocks. Dolomitic beds within individual carbonate units have pore throats of approximately 0.1 micron and core permeability in air of 0.4 to 0.01md. Current bottomhole pressure, matrix permeability, and microfracture permeability allow for fluid drainage across an extensive area, even though pore size and pore throats are very small. Analysis of modern openhole logs, magnetic resonance imaging logs (MRIL), stimulation-reservoir modeling, and production history of these reservoirs indicates that oil production from these dolomites will add additional producible reserves of 41° API gravity “yellow-wax” crude oil at low rates with extended production life.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana