Feasibility of the CO2-ESGR technique for providing carbon-negative shale gas: A life cycle assessment

To verify the possibility of producing negative-carbon shale gas by CO2-ESGR technology, a systematic approach based on life cycle assessment (LCA) method was developed to evaluate the net CO2 emission of CO2-ESGR covering its entire processes including CO2 capture, transportation, utilization and the consumption of the produced shale gas. As a case study, the CO2-ESGR in the Fuling shale reservoir was investigated using two CO2 injection methods, including huff & puff and continuous injection. Then, the net CO2 emission were analyzed using a Monte Carlo simulation with 10,000 randomly generated cases under two CO2 injection modes and four CO2 sources. The results indicated that both modes have the potential to produce negative carbon shale gas. However, for a system with the input of 1 ton CO2, the optimal net CO2 emission reduction for huff & puff CO2 injection mode is 0.21 tons, which is lower than the continuous mode with the net CO2 emission reduction of 0.70 tons under the same condition. Finally, the shale gas reservoirs of Chongqing in the case study shows great potential for the application of CO2-ESGR technique. The results verify that CO2-ESGR has significant potential for producing negative-carbon shale gas with the suitable source-sink matching. •LCA method for net CO2 emissions of CO2-ESGR was developed with two CO2 injection modes.•Monte Carlo simulations analysis under two injection modes with four CO2 sources were conducted.•The potential of CO2-ESGR technique for producing negative-carbon shale gas was verified•Continuous gas injection shows greater likelihood for producing negative-carbon shale gas.•CO2 source-sink matching should be optimized for improving the performance of CO2-ESGR.