Energy & Minerals

Project Overview

The Iron Springs district in southwest Utah is one of the largest iron producing regions in the western United States. A local mine recently proposed building a direct reduced iron plant to optimize their operations and increase the domestic supply of steel. We are conducting rigorous site characterization to assesses the CO₂ sequestration potential of subsurface geologic strata near the proposed plant to accommodate carbon-rich byproducts on a commercial scale. The region possesses world-class reservoir/seal packages at depths suitable for CO₂ storage and lacks evidence of an active petroleum system which lowers the risk of occluded pore space and overpressure, but considerable geologic uncertainty remains due to complex and poorly constrained subsurface conditions. Our characterization approach leverages new and existing geological and geophysical data for analysis of CO₂ storage capacity, reservoir and seal quality, and drilling hazards. Primary injection targets lie within eolian sequences of the Jurassic Navajo Sandstone (ɸ: ≤15%; μ: ≤156 mD), overlain by stacked confining units that include anhydrite-carbonate beds in the Temple Cap Fm. (Manganese Wash Mbr.) and gypsiferous shale and limestone of the Carmel Fm. (Co-Op Creek Mbr.), which itself was intruded by the Three Peaks quartz monzonite. Locally, the Navajo Sandstone lies entirely in the subsurface and few well penetrations provide only cutting samples. Preliminary thin section petrography work on cuttings from the ARCO Three Peaks #1 well reveals a range of lithofacies and fabrics that appear promising for CO₂ injection and storage. Reservoir analog data from nearby outcrop locations at Parowan Gap and Thunderbird Gardens exhibit different structural and depositional realms but rock mechanics and petrographic data from these locations provide potential end-member values for reducing reservoir quality uncertainties in our risk assessment. Attribute analysis of reprocessed 2D seismic data indicates laterally continuous subsurface reflectors and viable structural, stratigraphic, and volcano-stratigraphic trap styles, suggesting favorable reservoir / seal presence and continuity. A new gravity survey reveals an igneous intrusion sealing unit with greater volume and more complex geometry than previously identified. Each of these data inputs will be combined into a geomodel to simulate flow and CO₂ storage potential. Preliminary calculations indicate that current reservoir targets can store industrial volumes of CO₂ and saline water geochemical models yield encouraging results to greenlight eventual CO₂ injection. This study highlights how integrated basin analysis and reservoir characterization can provide key inputs for site selection and facility design, a first step on the path toward onsite CO₂ sequestration on new build industrial projects.