Ghost Ranch Field was discovered in 1996 on the basis of a 3-D (three-dimensional) seismic survey guided by analysis of log data from nearby existing wells. The 7 mi 2 (18 km 2 ) survey had the initial goal of identifying infill opportunities in Eagle Springs Field and led to the drilling of a series of new producers. Results from this activity, combined with log data from nearby Kate Spring Field, enabled the mapping of an oil-bearing Paleozoic slide-block mass between the two fields. A structural high with four-way closure, roughly 40-50 ac (16-20 ha) in size, was identified and successfully drilled to open Ghost Ranch Field. Ghost Ranch produces from fractured Devonian dolomites at depths of about 4350-4400 ft (1326-1342 m). The field has a strong water drive, an oil column of 100 ft (30 m), and estimated original oil in place (OOIP) of 2 million bbl. Production through January 1999 was 216.7 mbbl (11% OOIP) from three wells. Success at Ghost Ranch suggests that the updip margins of the productive slide-block mass define an excellent target for future exploration.