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Large Volume CO2 Storage; Reservoir Characterization and Plume Management

Abstract

The CO2 storage resource in California is very large, particularly in the Sacramento and Los Angeles Basins in Central Valley where reservoirs can be hundreds of feet thick and have high permeabilities (USGS 2013). For large volume storage in reservoirs like these, the challenge is not one of capacity, but one of lateral containment and plume volume management. This paper summarizes a reservoir simulation study on evaluating very large volume CO2 storage at a storage complex in Kemper County, Mississippi, USA. The work presented here included studying the storage capacity of the target reservoirs at the Kemper site, estimate the CO2 plume size, and perform a sensitivity analysis to examine the influence of reservoir and fluid properties, as well as the impact of active plume management, which includes water cycling (extracting water from down-dip wells and re-injecting it in up-dip wells within the storage formation) to mitigate CO2 plume migration and size. Considerable geological characterization of the Kemper storage site has taken place since 2016 and includes well drilling, coring, petrology, petrography, petrophysics, and sequence stratigraphy. These data were utilized to populate property (porosity and permeability) and structural models of the modeled area. Reservoir units occur from about 1,720 meters to 1,010 meters below ground surface, with over 350 meters of net sand. The CO2 storage reservoirs have exceptional quality, with mean reservoir porosity of 28.5% and mean reservoir permeability of 3.5 Darcy. To investigate field development strategies for large volume CO2 injection and storage at ECO2S, a base model was developed using the latest geological interpretation. In the model, CO2 injection was initiated through seven injection pads positioned in the center of the potential storage site. At the same time, active plume management, in the form of water cycling was also started in order to control the plume migration, extracting water from the southern (down-dip) part of the site and re-injecting it back through the northern (up-dip) part of the formation. The results of this study provide an illustration of methods to inject and manage large volumes of CO2 in high capacity, highly permeable reservoirs. Project ECO2S is part of the CarbonSAFE Program and is financially supported by the USDOE-NETL and Mississippi Power Company.