Reservoir characterization of a Permian deep-water sandstone, East Ford field, Delaware basin, Texas

Deep-water sandstones of the Delaware Mountain Group in west Texas and southeast New Mexico contained an estimated 1.8 billion bbl of original oil in place, but primary recovery from these fields is commonly less than 20%. East Ford field in Reeves County, Texas, which produces from the Ramsey sandstone in the upper Bell Canyon Formation, went directly from primary production to tertiary recovery by CO2 flooding. Field production has increased from 30 to more than 185 BOPD. Oil recovery has been improved by the CO2 flood, but not as much as expected. Geologic heterogeneities such as interbedded siltstones are apparently influencing reservoir displacement operations in the East Ford unit. A depositional model of the East Ford unit was developed using data from Bell Canyon outcrops and subsurface data. The Ramsey sandstones were deposited by turbidity currents in a basin-floor setting. The sandstones are interpreted as having been deposited in a channel-levee system that terminated in broad lobes; overbank splays filled topographically low interchannel areas. Injection wells located in splay sandstones apparently have poor communication with wells in channel sandstones, perhaps because communication is restricted through levee and channel-margin deposits. The south part of the unit is responding well to the flood because the injection and production wells are in the same interconnected lobe depositional environment.