Reservoir simulation for a CO₂ sequestration project

Davood Nowroozi, Donald C. Lawton

Time-lapse seismic surveys of a reservoir are an effective way to monitor alterations in the dynamic reservoir parameters and the fluid migration regimen during production or injection. The project is a study of a reservoir under a specified injection plan, using updated geological models in time and space. An existing reservoir model was utilized as the base case. This paper is the initial stage of a larger project; its focus is reservoir simulation. The reservoir was chosen from the Wabamun Area Sequestration Project (WASP). The WASP project was a CO₂ sequestration that was previously led by the University of Calgary.

The target layer for injection is the Nisku aquifer. It is a Devonian carbonate formation with high capacity (porosity) and injectivity (permeability), capped by the Calmar shale. These properties make it a suitable medium for CO₂ injection and efficient storage. A geomodel of the project was available. For this research an injection plan was defined with ten wells and constant bottom-hole injection pressure. The behavior of the reservoir was simulated for 50 years of injection and a further 50 years for prediction of the CO₂ plume shape and pressure changes in the reservoir.

After 50 years injection with constant bottom-hole pressure, the CO₂ plume only covered approximately 10% of the top layer of the Nisku aquifer of the geomodel area, but pressure changes occurred over the entire reservoir. At 50 years after injection termination, the mass of the plumes did not change meaningfully but pressure equalized across the entire reservoir. The defined plan can store 25% of the expected total CO₂ locally available for sequestration (20 Mt/year).