Grieve Unit

The Grieve Unit CO₂-EOR project is a tertiary recovery development located in central Wyoming (Natrona County / Wind River Basin region) targeting mature oil accumulations within the Cretaceous Muddy (Grieve) sandstone reservoir. The project transitioned from primary and waterflood recovery to miscible CO₂ injection to increase ultimate recovery and simultaneously sequester injected CO₂ in the subsurface. Development included drilling new wells, installing CO₂ pipeline infrastructure, upgrading field facilities, and converting patterns to CO₂ flood operations. The reservoir is characterized by stratigraphically trapped sandstones with structural dip conducive to gravity-stable CO₂ flooding, with injection designed to mobilize residual oil following earlier depletion phases. The project was advanced through partnerships including Elk Petroleum and Denbury Resources, with plans for significant incremental oil recovery while permanently storing injected CO₂ within the reservoir system.