Feasibility Study on Using Co2-Rich Industrial Waste Gas Replacement for Shale Gas Exploration Based on Adsorption Characteristics

Clean utilization of CO2-rich industrial waste gas ( CO2-rich IWG ) is of great significance to realize carbon neutralization. Due to the strong adsorption capacity of clay and organic matter in shale to CO2, it has a good potential for CO2-rich IWG storage and replacement. So, the feasibility of using CO2-rich IWG replacement for shale gas exploration from the perspective of adsorption was studied. A shale composite model was constructed based on the adsorption experiments, and the molecular simulation results were fitted with experiments for the model reliability. Then, the slit models of different minerals were constructed to study the adsorption mechanisms. Finally, the competitive adsorption mechanisms of different components with CH 4 were revealed. The results show that the overall adsorption capacity on shale minerals are ranked as HF>CO2>SO2>H2S>NO2>CH4>CO；Hydrogen bond and electrostatic force are the main adsorption modes of HF, and electrostatic force between negatively charged atoms of gas molecule and mineral surface is the main adsorption modes of CO2, SO2 and H2S. That of NO2 , CH4 and CO is the weak van der Waals force. In the competition with CH4 , the absolute adsorption capacity of gas decreases, but the relative adsorption capacity increases. The relative adsorption capacities of HF, CO2 , H2S and SO2 increase by 35, 26, 15 and 12 times, respectively. During competitive adsorption, negatively charged atoms in HF, CO2 , H2S and SO2 are more likely to bind with free cations on the surface of illite and smectite, and generate electrostatic repulsion for C atoms in CH4 , leading to the weakening or even disappearance of CH4 adsorption capacity