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Deposition and Diagenesis of Turbidite Sandstones in East Ford Field, Bell Canyon Formation, Delaware Basin, Texas

S. P. Dutton1 and W. A. Flanders2
1Bureau of Economic Geology, University of Texas at Austin, Austin, TX
2Transpetco Engineering, Midland, TX

Through 1998, reservoirs in deep-water sandstones of the Delaware Mountain Group in West Texas and southeast New Mexico produced 340 MMbbl of oil. East Ford field in Reeves County, Texas, is a Delaware sandstone reservoir that produces mainly from the Ramsey sandstone, the most prolific horizon in the Bell Canyon Formation. East Ford field recovered 2.9 MMbbl, or 16% of OOIP, during primary production, and it is currently undergoing a CO2 flood. Geologic heterogeneities caused by both depositional and diagenetic processes apparently are affecting reservoir displacement operations in East Ford field. The depositional model of the East Ford unit was developed on the basis of logs, one core, and pressure and production information from the field, supplemented by Bell Canyon outcrop data and information from nearby Geraldine Ford field. Ramsey sandstones were deposited in a basin-floor setting in a channel-levee system having attached lobes. Overbank splays are interpreted as being the main area of sand storage outside the channels. Porosity and permeability of the reservoir sandstones are controlled by calcite cement that is concentrated in layers ranging from 5 to 40 cm in thickness. Core analyses indicate that porosity in uncemented sandstones averages 23%, and geometric mean permeability is 44 md. In contrast, calcite-cemented sandstones average 12% porosity, and geometric mean permeability is 0.6 md. Permeability measured directly on the slabbed core face by an unsteady-state permeameter agrees well with core-plug permeability and allows close sampling of permeability variation around cemented zones.

AAPG Search and Discovery Article #90905©2001 AAPG Southwest Section Meeting, Dallas, Texas