Open-file Report 232 - New Mexico Bureau of Geology & Mineral ...

(Fig. 30). The Four Corners platform and the northern and
western parts of the central basin are assigned a high C02
potential. Natural gas that consists of more than 10% CO, has
been discovered in several wells and oil and gas (F.9. pools 24),
but economic quantities C02 of gas have not yet been discovered
on the Four Comers platform. C02 is produced commercially at
McElmo dome, 20 miles north of the New Mexico part of the Four
Corners platform. Reservoir quality Cretaceous sands are present
throughout the Four Comers platform and central part of the
basin. However, Cretaceous traps appear to be filled with
petroleum; C02 in Cretaceous traps has probably been diluted to
insignificant concentrations. Other reservoirs are the Entrada
Sandstone (Jurassic), Triassic sandstones, Permian sandstones,
Pennsylvanian carbonates, Mississippian sandstones, and
carbonates, and Devonian sandstones and carbonates. Analyses of
gases in the Paleozoic reservoirs (Fig. 29; Tables 24, 25'
indicates they are prone to C02 be rich. Gas in the Paleozoic
section may be trapped stratigraphically and structurally. The
Paleozoic section has been sparsely tested in San Juan County.
Cenozoic intrusive bodies are assigned a moderate po5ential
for C02 occurrence because the igneous rocks that form them are
poor reservoirs. It is possible that fractures and vesicles
within the intrusive rocks could serve as reservoirs for C02 tha
migrated into the intrusives from adjacent sedimentary units.
The southern and eastern parts of the San Juan Basin in Sa
Juan County are assigned a moderate-to-high potential for C02
occurrence (Fig. 30). Reservoirs and traps are probably similar
to those in the northern part of the county, but no analyses a
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