CO2 enhanced gas recovery and sequestration as CO2 hydrate in shallow gas fields in Alberta, Canada

In this study, we carry out reservoir simulations to investigate the effect of CO2 hydrate formation on CO2 storage capacity in shallow gas fields. Results show that CO2 hydrate formation moderates the reservoir pressure due to volume shrinkage thus allowing more CO2 (122-212% pore volume) to be stored. The CO2 storage capacity in a gas field with CO2 hydrate formation is up to 3.2 times that without CO2 hydrate formation. Due to CO2 hydrate formation, the CO2 storage capacity in a gas field first increases when initial water saturation increases from 0.1 to 0.3 but then decreases when the initial water saturation increases from 0.3 to 0.5. However, the CO2 storage capacity decreases with an increase in initial water saturation if there is no CO2 hydrate forms. Results of screening show that out of 68,327 gas fields in Alberta, 517 gas fields can be used to store CO2 as CO2 hydrate, giving a total CO2 storage capacity of 536 Mt. Of this, depleted gas fields in Alberta have the highest CO2 storage capacity including the Chard and Saleski gas fields with storage capacity of 138 Mt and 94 Mt, respectively.