RESIDUAL OIL ZONE FAIRWAYS, OIL FIELDS
Permian basin area
Capitan Fairway North Cowden
Kinder Morgan recently implemented a project that
proved greenfield ROZ exploitation was feasible via EOR
techniques. Greenfield ROZs exist where no MPZ is found
above the ROZ.
Operators envisioning an alternative commercial exploitation strategy other than EOR methods (particularly CO2
injection) witnessed a technological turn in 2013 when reservoir depressuring was also shown to commercialize greenfield ROZs.
Horizontal drilling and well stimulation advances in
shale reservoirs over the past 20 years have now led to the
application of these methods in carbonate ROZ reservoirs.
Manzano LLC of Roswell, NM, drilled a 4,500-ft lateral
in the San Andres formation in Lea County, NM, completing the well with hydraulic fracturing. The formation was
believed to be the carbonate equivalent of tight shales (low
permeability). But field experience disproved that belief.
Completion resulted in production of more than 2,000
b/d of water. Manzano continued to produce the well for
30 days with minor volume depletion. Reservoir pressures
dropped by about one-third at which point oil and gas production began.
Drilling was within the mapped ROZ fairway in the midst
of vertical (non-commercial) dry holes. Analysts began to
believe the oil was at least partially residual, liberated by gas
expansion when reservoir pressures fell.
Other operators have expanded horizontal drilling into
other regions of the ROZ fairways and other counties beyond
Lea and Yoakum.
Fig. 2 shows ROZ fairway mapping with superimposed
major Permian and Pennsylvanian fields. Understanding the
San Andres ROZ (greenfield) fairways helps explain past
and ongoing plays such as the Hunton dewatering in Oklahoma, and the Yeso formation and Dagger Draw dewatering
field in New Mexico.
Geologists have applied tools developed in the San An-