HYDROGEOLOGICAL AND NUMERICAL-ANALYSIS OF CO2 DISPOSAL IN DEEP AQUIFERS IN THE ALBERTA SEDIMENTARY BASIN

For landlocked large sources of CO2, the best approaches for reducing CO2 emissions into the atmosphere are its utilization and deep disposa l into deep sedimentary aquifers or depleted oil and gas reservoirs. A number of coal-based power plants (total capacity of more than 4000 M W) are located near Lake Wabamun in central Alberta, Canada. A hydroge ological study of the sedimentary succession at the site was undertake n to identify and select aquifers which meet various requirements for CO2 disposal, particularly with respect to depth and confinement. The multi-phase, multi-component numerical model STARS was used to study t he ability of the selected aquifers to accept and retain for long peri ods of time large quantities of CO2 injected in a supercritical state. The CO2 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 numeri cal simulations indicate that even generally low-permeability aquifers can accept and retain large quantities of CO2, showing that injection of CO2 in a supercritical state into deep aquifers in sedimentary bas ins is a viable option and may be the best short-to-medium term soluti on for reducing CO2 emissions into the atmosphere. The CO2 injectivity is enhanced by the existence of 'sweet' zones of high permeability.