Comprehensive Characterization of a Potential Site for CO2 Geological Storage in Central Alberta, Canada

Abstract

A significant number of large CO2 emitters are located in central Alberta, Canada, including four coal-fired power plants in the Wabamun Lake area, with cumulative annual emissions in the order of 30 million metric tons CO2. To help industry and regulatory agencies in selecting and permitting sites for CO2 storage, proper characterization is essential, covering the principal aspects of CO2 storage: capacity, injectivity, and confinement. The sedimentary succession in the Wabamun Lake area southwest of Edmonton was identified as a potential CO2 storage site because it would minimize transportation needs and costs from the large CO2 sources in the vicinity. A wealth of data on stratigraphy and lithology; fluid compositions; rock properties; and geothermal, geomechanical, and pressure regimes were used to create and characterize a comprehensive three-dimensional model of the deep saline aquifers in the area that could be CO2 storage targets. These aquifers have sufficient capacity to accept and store large volumes of supercritical CO2 at the appropriate depth and are overlain by thick confining shale units. Initial calculations and modeling of CO2 injection into the Devonian Nisku carbonate aquifer suggest that dissolution and residual saturation of CO2 limit the lateral CO2 plume spread considerably. Hypothetical injection of 12.5 million tonnes/yr of CO2 for 30 yr would result in a maximum plume spread of less than 15 km (9 mi) in diameter. However, multiple injection wells would be needed to inject this large amount of CO2 to maintain bottomhole injection pressures below the rock-fracturing threshold.