Feasibility study of underground CO2 storage through Water Alternative Gas (WAG) operation: A case study in Southwestern Ontario
Mohamad Mohamadi‐Baghmolaei, Dru Heagle, Ali Ghamartale, Amin Izadpanahi
Abstract
Geological CO 2 storage (GCS) offers a promising, low-risk, long-term solution for carbon sequestration . This study assesses the feasibility of GCS water-alternating-gas (WAG) operations in a brine formation targeted for the Western Ontario GCS plan. The Cambrian strata shows potential for CO 2 storage but faces challenges like limited lateral extension and geopolitical issues from plume migration. To mitigate these risks, a deep evaluation of CO 2 trapping mechanisms is crucial. CO 2 dissolution into brine provides secure storage by reducing the free plume. The proposed WAG operation promotes dissolution, using a vertical equilibrium model coupled with a black oil model to estimate CO 2 trapping proportions during and post-injection. The Taguchi design of experiments investigates various WAG scenarios with minimal simulations, reducing numerical costs. Sensitivity analysis/optimization of WAG parameters, including water extraction rate (WER), water injection rate (WIT), and CO 2 injection time (CIT), ranked their effectiveness in CO 2 dissolution. Optimal WAG operations can reduce the free plume by 49 % and increase the dissolution ratio from 0.26 to 0.52. CIT and WIT were found to be the most influential factors, contributing 42 % and 31 % to CO 2 dissolution, and 43 % and 34 % to overall CO 2 trapping, respectively, while WER exhibited a lower impact of 8–9%.