Geological Screening for CO2 Storage in Deep Saline Aquifers in the Lower Mainland British Columbia (LMBC), Canada

Abstract

Deep saline aquifers and depleted reservoirs are prime candidates for CO₂ storage, but feasibility assessments remain limited in regions with little oil and gas activity, such as the Lower Mainland of British Columbia (LMBC), Canada. This study evaluates the CO₂ storage potential of the Georgia Basin strata beneath the LMBC, focusing on three intervals (Nanaimo Group, Huntingdon Formation, and Boundary Bay Formation) in Western, Central, and Eastern LMBC. Eastern LMBC holds limited potential for CO₂ storage due to both the shallow depth of strata in that region and the high geological uncertainty resulting from limited subsurface data. The Upper Cretaceous Nanaimo Group across the entire LMBC is unsuitable for CO₂ injection because it has very poor reservoir quality (generally <1 mD permeability and <8% porosity). In contrast, the Paleogene Huntingdon Formation in Western and Central LMBC contains thick successions of reservoir-quality rock (average thickness: 110 m, porosity: 15%), though its low permeability (≥10 mD) may restrict injection rates. Its estimated CO₂ storage capacity is ∼400 Mt, making it a secondary target. The Neogene Boundary Bay Formation, also in Western and Central LMBC, offers the most favorable conditions, with higher permeability (13–67 mD), porosity (18%–21%), and thick reservoir intervals (up to 155 m). It has an estimated CO₂ storage capacity of ∼430 Mt. With low fault density and minimal wellbore leakage risks, the Boundary Bay Formation and then the Huntingdon Formation below Western and Central LMBC are recommended as the primary targets for CO₂ sequestration in the region.