Effect of Rock Mineralogy on Hot-CO2 Injection for Enhanced Gas Recovery

Conventional gas reservoirs are one of the viable options for CO2 enhanced gas recovery and sequestration. Injection of hot CO2 into depleted reservoirs is expected to improve gas recovery. Static adsorption and core flooding experiments were performed to quantify methane/CO2 adsorption/desorption using different rocks at different temperatures and pressures. Rocks such as shale, tight sandstone, calcite, and dolomite were used. For calcite, theoretical simulations were performed. Though methane desorption has increased when the temperature was raised, the results suggest that the gas recovery has doubled when the temperature has been increased from 50° to 100 °C in conventional reservoirs and from 100° to 150 °C in conventional and unconventional reservoirs. Similar trends were obtained for different rocks with increasing temperature. Core flooding and static adsorption experiments showed matching results. Rock mineralogy affects the adsorption capacity of the rock with shale rock having a 60% higher methane production than sandstone.