Geological Development of the Lonesome Dove II King Sand field

Abstract

In March of 1989, Marshall and Winston, Inc., drilled Petro-West Corporation's Brady Creek prospect, 5 mi southwest of Eden, Concho County, Texas, along the southern part of the eastern shelf of the Permian basin. The prospect was drilled on the basis of a subsurface, geological anomaly mapped on the lower King Sandstone. The anomaly was confirmed and enhanced by soil gas geochemistry. The McMurtrey No.1 well encountered 38 ft of sandstone, and has an estimated potential of 79 BOPD (pumping). The lower King Sandstone at Lonesome Dove II field is part of a larger northeast-southwest-trending Cisco depositional system. Data from subsequent drilling at Lonesome Dove II (including two conventional cores, samples, sidewall cores, dipmeters, and electric logs) indicates that the lower King Sandstone may have been deposited during a regressive cycles of fluvial-deltaic sedimentation. Characteristics of both fluvial point bar and distributary channel facies have been noted and the development of a distributary model of deposition led to the extension of the field beyond the limits of the original subsurface and geochemical picture. The presence of two or more separate channels or channel systems is indicated by isopach maps and by significant oil gravity, field pressure, and grain size differences.more » These channel systems may have been deposited on a relatively flat-lying deltaic plain as indicated by cross sections showing only slight channel downcutting.« less