Shirley P. Dutton,1 and William A. Flanders2
Deep-water sandstones of the Delaware Mountain Group in west Texas and southeast New Mexico contained an estimated 1.8 Bbbl of original oil in place. Primary production from these fields is commonly less than 15%, and secondary waterfloods recover only an additional 45% OOIP. Low recovery efficiencies from Delaware sandstone fields are caused mainly by high water production without a water drive. East Ford field, a Delaware Sandstone field that produces from the Ramsey sandstone in the upper Bell Canyon Formation, went directly from primary production to tertiary recovery by CO2 flooding. CO2 injection began in July 1995, and production response was observed in December 1997. Field production has increased from 30 bbl/day to more than 150 bbl/day.
The upper and lower Ramsey sandstones at East Ford field were deposited by turbidity currents in a basin-floor setting. Sandstones were deposited in a channel-levee system that terminated in broad lobes; overbank splays filled topographically low interchannel areas. Geologic heterogeneities apparently affect reservoir displacement operations in East Ford field. Injectors in splay sandstones apparently have poor communication with wells in channel sandstones, perhaps because communication is restricted through levee deposits. The field also appears to be divided into three areas of better interwell communication; communication between wells in different areas is restricted. The areas may result from facies changes, subtle structural or bathymetric controls on deposition, or variations in sediment transport direction.
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.