Denver Unit

The Denver Unit (DU) is part of the larger Wasson San Andres (WSA) CO₂-Enhanced Oil Recovery (CO₂-EOR) project operated by Occidental Permian LTD and OXY USA WTP, subsidiaries of Occidental (Oxy), in the Permian Basin, Texas. The WSA complex includes multiple operating units: the Denver Unit (DU), Willard Unit (WU), Wasson ODC Unit (WODC), Bennett Ranch Unit (BRU), Ownby San Andres Unit (OSAU), Cornell Unit (CU), and Mahoney Unit (MU). CO₂ flooding occurs within the San Andres Formation, a thick, porous, and permeable carbonate reservoir with secondary and tertiary confining zones that provide long-term containment and low leakage risk. Water flooding began in the mid-1960s, CO₂ flooding followed as part of tertiary recovery, and Oxy assumed operations in 2000. Anthropogenic and recycled CO₂ is transported through a trunkline network and injected using pattern-based miscible flooding, including Water Alternating Gas (WAG) cycles to maintain reservoir pressure above minimum miscibility pressure while remaining below formation parting pressure. Produced gas streams are processed through centralized recovery infrastructure including the Denver Unit CO₂ Recovery Plant (DUCRP), Willard Unit CO₂ Recovery Plant (WUCRP), Wasson CO₂ Recovery Plant (WCRP), and Bennett Ranch Unit Reinjection Compression Facility (BRU RCF). Monitoring under EPA Subpart RR uses mass-balance accounting to quantify CO₂ received, injected, recycled, and permanently stored within the reservoir.