CO2 -hydrate formation in depleted gas reservoirs–A methodology for CO2 storage.

Abstract: With the growing concern about climate change, interest towards reducing CO₂ emissions has increased. Geological storage of CO₂ is perceived to be one of the most promising methods that could provide significant reduction in CO₂ emissions over the short and medium term. Since a major concern regarding geological storage is the possibility of leakage, trapping CO₂ in the solid form is quite attractive. Unlike mineral trapping, the kinetics of CO₂-hydrate formation is quite fast, providing the opportunity for long-term storage of CO₂. In this paper, we study storage of CO₂ at conditions similar to those at depleted gas pools of Northern Alberta. Thermodynamic calculations suggest that CO₂ hydrate is stable at temperatures that occur in a number of formations in Northern Alberta, in an area where significant CO₂ emissions are associated with production of oil sands and bitumen. Numerical simulation results presented in this paper suggest that, upon CO₂ injection into such depleted gas reservoirs, pressure would initially rise until conditions are appropriate for hydrate formation, enabling storage of large volumes of CO₂ in solid form. These results show that, because of tight packing of CO₂ molecules in the solid (hydrate), the CO₂ storage capacity of these pools is many times greater than their original gas-in-place. This provides a local option for storage of a portion of the CO₂ emissions there. [Copyright &y& Elsevier]