2. The Story of the Wyoming Carbon Underground Storage Project (WY-CUSP), and the Regional Inventory and Prioritization of Potential CO₂ Storage Reservoirs in Wyoming

The Wyoming Carbon Underground Storage Project (WY-CUSP) is a statewide effort to identify, inventory, prioritize, and characterize the most outstanding CO₂ storage reservoirs and the premier storage site in Wyoming. The WY-CUSP project is managed by the Carbon Management Institute (CMI) at the University of Wyoming with support from the US Department of Energy, State of Wyoming, and industrial partners. In its search for an optimum carbon dioxide storage reservoir in Wyoming, CMI first inventoried and examined the state’s hydrocarbon reservoirs, for these are reservoirs with proven fluid storage capacity. The inventory and prioritization of storage reservoirs and storage sites was based on the following criteria: (1) thickness, areal extent, and petrophysical properties of the reservoir rocks, (2) presence of a fluid trap and adequate confining layers, (3) suitable temperature, pressure, and rock/fluid chemistry regimes, (4) salinity of the formation fluids in the storage reservoir rocks, and (5) volumetrics of the storage site. It became apparent that the Mississippian Madison Limestone and Pennsylvanian Weber/Tensleep Sandstone were the highest-priority potential CO₂ storage stratigraphic intervals, and that the Rock Springs Uplift (RSU) in southwestern Wyoming was the premier CO₂ storage site in the state. A drill site on the northeastern flank of the RSU was highly prospective in offering high-quality reservoir rock at a depth that provides sufficient temperature and pressure for carbon dioxide storage. A very-large-scale, large-capacity trap on the RSU has several competent sealing rock units, and available data show that the reservoir rocks contain very saline formation water. Abundant sources of carbon dioxide are nearby, notably the Jim Bridger Power Plant.