Long-term storage of CO2 gas in porous rock is considered a promising route for decreasing CO2 emissions. In some cases, this storage can even improve yields from associated fossil-fuel mining activities. The 'CO2 sorption and flow in shale reservoirs' (CO2SHALESTORE) project investigated whether gas-bearing shale can be used to store CO2. They also looked at whether CO2 injection could be used to improve yields from gas-bearing shale fracturing activities. Five shale samples were collected from an area in Poland and sent to the laboratory for analysis. The project first analysed the composition of these shales to understand any changes that would occur after long-term CO2 storage. Researchers also assessed the CO2 storage capacity of these shales by injecting CO2 gas at high pressure. The project found that without the presence of organic carbon in the shale, CO2 storage was dependent on high clay content. Overall, CO2SHALESTORE showed that the shales could not store large amounts of CO2. Further, the presence of CO2 did not improve methane recovery. Researchers concluded that more work was required to find a successful way to store CO2 in gas-bearing shales.
CO2, shale reservoirs, gas-bearing shale, shale fracturing, methane recovery