Technical and economic feasibility of CO 2 disposal in aquifers within the Alberta sedimentary basin, Canada

Abstract

A three year study of the technical and economic feasibility of aquifer disposal of CO 2 in the low permeability sedimentary rocks of the Alberta Basin has revealed several new generic concepts that may be applicable to other sedimentary basins throughout the world. High permeability aquifers are not necessarily required for CO 2 disposal. Injectivity of CO 2 can be maximized by siting disposal wells in targeted or “sweet” zones of locally high permeability surrounded by a low regional scale permeability [1–2]. The low regional permeability forms a “hydrodynamic” or “time” trap for CO 2 [1], where the residence time of CO 2 in the aquifer is of the order of 10 5 to 10 6 years. Another type of hydrodynamic trapping in sedimentary basins is produced by the “sponge” or “sink” effect of rebounding shales [3–4]. On a smaller time scale, over hundreds of years, “mineral” or “inert” trapping [5–6] by reaction of the CO 2 with basic aluminosilicate minerals will occur in siliciclastic aquifers. Consequently, stratigraphic traps may not be necessary for safe disposal of CO 2 in the subsurface. Aquifer disposal of CO 2 is expensive, on the order of $52/tonne. Although there are many possibilities to reduce CO 2 emissions that are more economically attractive, aquifer disposal remains as one of the largest sinks available for CO 2 in landlocked areas of the world; and may be utilized if other less expensive options are exhausted.