Basin-scale modeling of CO2 sequestration via multiple storage sites - Great Plains Basal Aquifer System, Canada

The northern Great Plains Basal Aquifer System spans an area of ~811, 000 km2 in the south western Canadian states and is considered an important potential site for sequestration of carbon dioxide. To assess the dynamic storage capacity of the Basal Aquifer system, we selected eleven well clusters with a total of 50 injection wells using CO2 source-sink mapping in Alberta and Saskatchewan. The injection rate for each cluster ranges from 1.2 to 23 Mt CO2 per year, with a total rate of 75.1 Mt CO2/year, corresponding to 86% of the emissions from all large point sources in the region. The data of the stationary sources and detailed hydrogeological information were provided by Alberta Innovates—Technology Futures (AITF). The geologic model of the deep saline system consists of the caprock, the Basal Aquifer, and the Precambrian basement. The heterogeneity of the storage aquifer is relatively high, as porosity varies from 1 % to 25 % and permeability from 10 to 1000 mD, with a maximum aquifer thickness of 300 m. Simulations were performed using TOUGH2 with its fluid property module ECO2N on an unstructured 3D grid. The grid resolution is fine in the vicinity of the injection wells and progressively decreases with increasing distance from the injection sites, i.e, resolution ranging from 50 m and 20 km. Simulations were conducted to quantify basin-scale pressure buildup and dynamic storage capacity, together with distribution, migration, and long-term fate of CO2 plumes in response to CO2 injection and storage.