Effect of geologic depositional environment on CO₂ storage efficiency

The storage potential and movement of fluids within a formation is dependent on hydraulic characterization unique to each depositional environment. Storage efficiency (E), the ratio of the injected volume of CO₂ to the accessible pore volume, quantifies the CO₂ storage capacity in a geologic depositional environment, providing a means to assess the CO₂ storage resource of candidate reservoirs. This paper quantifies the ranges for E via numerical modeling for eight depositional environments: deltaic, shelf clastic, shelf carbonate, fluvial deltaic, strandplain, reef, fluvial and alluvial, and turbidite. An important aspect of this work is the development of geologic and geocellular modeling that reflects the uniqueness of each depositional environment. Depositional environments were interpreted from core and geophysical log data; geologic and petrophysical data from oil fields and gas storage sites were used as constraints in the development of geocellular models, which were upscaled for flow simulations. Evaluation of the effects of geologic structures on storage efficiency indicates it causes a net increase in efficiency. Fluvial deltaic had the highest E and shelf carbonate had the lowest.