Near Gas-Water Contact Sequestration of Carbon Dioxide to Improve the Performance of Water Drive Gas Reservoir: Case Study

This study investigates the application of carbon dioxide (CO₂) sequestration to address challenges in water-drive gas reservoirs, specifically focusing on improving gas recovery and mitigating water invasion. Traditional methods like blow-down and co-production have limitations, including sand production, water coning, and inefficiency in strong aquifers. To overcome these issues, this research explores CO₂ injection near the edge aquifer, aiming to reduce water influx and enhance gas recovery through the propagation of a CO₂ plume in the gas-water contact zone. Both synthetic and real compositional reservoir models were studied, with CO₂ injection performed while maintaining reservoir pressure below 90% of the initial level. Results show that CO₂ sequestration significantly improved recovery, particularly in higher permeability reservoirs, where it reduced aquifer influx and increased gas production by 26% under challenging conditions. While CO₂ dissolution in water decreased aquifer influx by 39%, its adverse effect on sweep efficiency led to a reduction in gas and water production by 4.2% and 10%, respectively. The method's effectiveness was not significantly impacted by aquifer permeability, but it was sensitive to vertical-to-horizontal permeability ratios. When applied to a real gas reservoir, the proposed method increased gas production by 14% compared to conventional techniques, with minimal CO₂ production over a 112-year period. This study demonstrates the potential of CO₂ sequestration as a comprehensive solution for enhancing gas recovery, reducing water production, and mitigating environmental impacts in water-drive gas reservoirs.