Carbon dioxide storage in depleted gas reservoirs in northeastern Alberta: Prioritizing CO2 storage sites within a CCS value chain framework

Abstract

Thousands of depleted shallow gas reservoirs in northeast Alberta offer a promising CO₂ storage complements to deep saline aquifers, supporting carbon removal in the oilsands region. This study presents a three-step framework to evaluate their suitability: a) initial screening to ensure sufficient capacity and injectivity, and containment, b) multi-criteria ranking to identify the most strategic candidates, and c) source–sink (S–S) optimization to integrate spatial and economic constraints within a carbon capture and storage (CCS) value chain framework, enabling the prioritization of optimal storage sites. From an initial inventory of 4694 depleted pools, 874 reservoirs with a combined capacity of 1518 Mt CO₂ were shortlisted. These were aggregated into fields and further integrated into four distinct trends based on geological and engineering characteristics within a CCS value chain framework. The Lower Cretaceous Kirby–Leming rend emerged as the most favorable, with capacity of 772 Mt CO₂, strong injectivity, and economic viability. The Resdeln–Duncan trend followed closely, having a storage capacity of 366 Mt CO₂, offering similar geological advantages but located farther from proposed pipelines. The Craigend–Lindbergh trend, while less optimal geologically with smaller capacity of 227 Mt CO₂ storage, aligns well with the planned Oil Sands Pathways Alliance CO₂ hub, making it a strategic complementary site. In contrast, the Devonian carbonate reservoirs in the Granor–Ukalta trend ranked lowest due to poor injectivity, long transport distances and lower capacity of 154 Mt. Altogether, the top three trends offer nearly 1400 Mt of storage potential. This study pinpoints high-potential CO₂ storage zones, providing insights for regional carbon management strategies. Integrating shallow gas reservoirs into Alberta’s CCS infrastructure could accelerate near-term carbon removal while reinforcing long-term net-zero objectives.