EOLIAN RESERVOIR TARGETS FOR CARBON CAPTURE AND SEQUESTRATION, CENTRAL UTAH

The Department of Energy’s CarbonSAFE Rocky Mountain prefeasibility initiative characterized several eolian formations of central Utah to understand their storage capacity and viability as carbon capture and sequestration (CCS) reservoirs for nearby coal-fired power plants. Initial outcrop observations of the Permian White Rim Sandstone, the Jurassic Wingate Sandstone, and the Jurassic Navajo Sandstone indicated that these units have sufficient thickness, lateral continuity, and reservoir properties to warrant additional investigation. Field and laboratory methods provided inputs for reservoir characterization as well as for static and dynamic modeling performed by collaborating teams. Measured sections, outcrop photomosaics, facies descriptions, and in situ mini-permeameter measurements provided the overall framework for laboratory analysis including porosity and permeability measurements, thin section petrography, and visible and near infrared spectroscopy.

All three eolian formations could provide the necessary gross rock volume for CCS; however, the units have significant differences in the relative reservoir quality. Thick accumulations of decimeter to decameter scale crossbedded sandstones of wind ripple and grain flow laminae comprise the dune deposits. Horizontally bedded lenticular sandstones and carbonates comprise the interdune deposits. The White Rim Sandstone also has an upper 4-10 m zone modified by marine reworking with a diverse marine shoreface trace fossil assemblage. Overall, the Navajo Sandstone shows significantly higher permeability values in both the grain flow facies (100s-1000s mD) and wind ripple facies (10s-100s mD) compared to the same facies in both the White Rim and Wingate Sandstones (100s of mD in the grain flow facies and 10s of mD in the wind ripple facies). Diagenetic histories deduced from subsurface core data indicate that the White Rim Sandstone experienced significant reduction of primary porosity due to extensive quartz overgrowth and carbonate cements. Reservoir quality trends and diagenetic alteration histories indicate that the Navajo and Wingate Sandstones are potentially suitable CCS reservoirs, whereas the White Rim Sandstone lacks sufficient preserved porosity and permeability to store economic volumes of supercritical CO₂.