Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
AAPG Southwest Section Convention, Dallas, Texas, March 1013, 2001
and Diagenesis of Turbidite Sandstones in East Ford Field,
Shirley P. Dutton,1 and William A. Flanders2
Reservoirs in deep-water sandstones of the Delaware Mountain Group in west Texas and southeast New Mexico have produced 340 MMbbl of oil through 1998. 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 percent of OOIP, during primary production, and it is currently undergoing a CO2 flood.
Geologic heterogeneities caused by both depositional and diagenetic processes apparently affect 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 the nearby Geraldine Ford field. Ramsey sandstones were deposited in a basin-floor setting in a channel-levee system with attached lobes. Overbank splays are interpreted as being the main area of sand storage outside of 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 thick. 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.
1Bureau of Economic Geology, The University of Texas at Austin, University Station Box X, Austin, Texas 78713; e-mail: firstname.lastname@example.org.
2Transpetco Engineering, 110 N. Marienfeld Place, Suite 525, Midland, Texas, 79701; e-mail: email@example.com.