Geological Potential for Sequestration of CO2 as Gas Hydrate in the Alberta Portion of the Western Canada Sedimentary Basin

摘要

The Alberta portion of the WCSB has been investigated with respect to the geological potential for the sequestration of CO2 as a meta- stable, solid crystalline gas hydrate. Based on a coarse-resolution (1 km~2) geothermal analysis and industry borehole data, the areas north of Cold Lake and south/southwest of Fort McMurray have been identified as having pressure-temperature (P-T) conditions favourable to the formation and maintenance of CO2 hydrate at target injection intervals of 300-400 m depth. It is estimated that the gross amount of CO2 that could be sequestered as gas hydrate in Alberta is approximately 46 Gt. The presence of a substantial overburden provides an effective buffer against the propagation of anticipated warmer surface temperatures (due to progressive climate warming) into the ground at depth. Numerical modeling predicts a time frame of between 1000-2000 years for a 3°C change in surface air temperature to effect an increase in ground temperature of 1°C at 300 m depth. This preliminary regional assessment offers a potential new strategy for the geological sequestration of CO2 in Canada, however considerable additional work is required to advance this idea from concept to practice. Specifically, the acquisition of more reliable ground temperature data and local geothermal gradients, pore water geochemistry, porosity and permeability would be a pre-requisite to the implementation of a small-scale demonstration project in a readily accessible region of northeastern Alberta.