CHSU Miller EOR Facility

The CHSU Miller EOR Facility is a CO₂-enhanced oil recovery project located in Wyoming within the Rocky Mountain region, developed to increase recovery from mature conventional oil reservoirs through miscible or near-miscible CO₂ injection. The project targets sandstone reservoirs characterized by structural and stratigraphic trapping typical of Rocky Mountain foreland basin systems. Field development followed the standard progression of primary production followed by secondary recovery (waterflooding) prior to conversion to tertiary CO₂ flooding to mobilize residual oil saturation. CO₂ is injected through Class II wells in a pattern flood configuration, often incorporating water-alternating-gas (WAG) cycles to manage mobility and improve sweep efficiency in heterogeneous reservoir intervals. The facility includes compression, recycle, and handling infrastructure to process produced gas streams containing both hydrocarbons and CO₂, enabling separation and reinjection of recovered CO₂. Injected CO₂ enhances recovery through oil swelling, viscosity reduction, and interfacial tension changes, while a portion remains trapped in the subsurface through structural, residual, and dissolution trapping mechanisms.