Hydrogeological and numerical analysis of CO 2 disposal in deep aquifers in the Alberta sedimentary basin

Abstract

For landlocked large sources of CO 2, the best approaches for reducing CO 2 emissions into the atmosphere are its utilization and deep disposal into deep sedimentary aquifers or depleted oil and gas reservoirs. A number of coal-based power plants (total capacity of more than 4000 MW) are located near Lake Wabamun in central Alberta, Canada. A hydrogeological study of the sedimentary succession at the site was undertaken to identify and select aquifers which meet various requirements for CO 2 disposal, particularly with respect to depth and confinement. The multi-phase, multi-component numerical model STARS was used to study the ability of the selected aquifers to accept and retain for long periods of time large quantities of CO 2 injected in a supercritical state. The CO 2 injectivity of the selected aquifers was examined for a whole series of parameters, including aquifer depth and thickness, rock and formation water properties, and injection characteristics. The numerical simulations indicate that even generally low-permeability aquifers can accept and retain large quantities of CO 2, showing that injection of CO 2 in a supercritical state into deep aquifers in sedimentary basins is a viable option and may be the best short-to-medium term solution for reducing CO 2 emissions into the atmosphere. The CO 2 injectivity is enhanced by the existence of ‘sweet’ zones of high permeability.