ASSESSING THE GEOLOGIC CARBON (CO2) SEQUESTRATION POTENTIAL OF MULTIPLE SUBSURFACE TARGETS IN THE IRON SPRINGS DISTRICT, IRON COUNTY, UTAH

The Iron Springs District in SW Utah lies at the eastern boundary of the Basin and Range Province as it transitions into the Colorado Plateau. The region comprises N-NE-trending basement-cored uplifts and grabens that juxtapose thick sequences of Paleozoic and Mesozoic strata and extensive Eocene-and-younger volcanics, all of which have been heavily faulted. This area is potentially suitable for CO2 sequestration for several reasons: the presence of multiple, world-class reservoir/seal packages at depths suitable for CO2 storage; the absence of an active petroleum system which lowers the risk of occluded pore space and overpressure; and possible low drilling and injection costs due to relatively shallow depths for some targeted reservoirs. Favorable injection targets include (1) the Jurassic Navajo Fm., an eolian sandstone (ɸ: ≤15%; μ: ≤156 mD, historically), overlain by Carmel Fm. gypsiferous shale, which itself was intruded by the Three Peaks quartz monzonite laccolith during Oligocene-Miocene time, and (2) the Permian Kaibab Limestone (documented as intensely fractured and underpressured), overlain by the mudstone-dominated Triassic Chinle Fm. Preliminary calculations indicate that reservoir targets can store industrial volumes of CO2. Assessment of the ~180-km study area requires an integrated subsurface characterization workflow that leverages new and existing geological and geophysical data for rigorous site characterization and analysis of CO2 storage capacity, seal quality, drilling hazards, and economic contingency planning. Reprocessed 2D seismic data show several viable trapping elements including Sevier-age structural duplexes in the Iron Springs Thrust Fault system and contacts (some thermally altered) between injection targets and the laccolith. Geophysical surveys of terrestrial gravity complement seismic time-to-depth conversion and delineate basin structure and laccolith extent while rock materials and geophysical logs from nearby petroleum exploration wells are used to characterize the petrophysical properties of reservoir/seal pairs. Well cuttings analysis includes detailed imaging, lithologic description, and chronostratigraphic refinement. Lessons learned from unique operational and technical challenges will be applied elsewhere in Utah’s Great Basin.