Ghost Ranch field was discovered in 1996 on the basis of a 3-D (three-dimen
sional) 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 in
fill opportunities in Eagle Springs field and led to the drilling of a seri
es of new producers. Results from this activity, combined with log data fro
m nearby Rate Spring field, enabled the mapping of an oil-bearing Paleozoic
slide-block mass between the two fields. A structural high with four-way c
losure, roughly 40-50 ac (16-20 ha) in size, was identified and successfull
y drilled to open Ghost Ranch field. Ghost Ranch produces from fractured De
vonian dolomites at depths of about 4350-4400 ft (1326-1342 m). The held ha
s a strong water drive, an oil column of 100 ft (30 m), and estimated origi
nal oil in place (OOIP) of 2 million bbl. Production through January 1999 w
as 216.7 mbbl(11% OOIP) from three wells. Success at Ghost Ranch suggests t
hat the updip margins of the productive slide-block mass define an excellen
t target for future exploration.