热效应和驱替效应下含压裂液煤层多分子竞争吸附规律研究OA

In order to investigate the competitive adsorption pattern of N2/CH4 gases in coal under thermal and displacement effects,the study is based on the macromolecular model of bituminous coal,the adsorption behaviors of methane molecules,water mo-lecules and fracturing fluid molecules under heated nitrogen injection are simulated by molecular dynamics and Monte Carlo meth-ods,to investigate the interaction energy between fracturing fluid and coal surface molecules,and the microscopic laws of different gas injection temperatures,water contents and pore diameters on the competitive adsorption of N2/CH4.The results show that:the in-teraction between fracturing fluid molecules and coal molecules is 18.469 kJ/mol,the van der Waals interaction force between the systems is 23.732 kJ/mol,the electrostatic interaction force is-598.125 kJ/mol,and the stability of the system between the fracturing fluid molecules and the coal molecules is poor,which provides conditions for the injection of heated nitrogen to increase the seepage of the de-blocking;in the process of heated nitrogen injection,along with the increase of temperature,the adsorption capacity of N2 relative to CH4 in the model is enhanced;the increase in water content leads to a significant decrease in the adsorption of both CH4 and N2,and the adsorption capacity of CH4 remains stronger than that of N2 in the model;pore size has a significant effect on N2 ad-sorption,the dominance of CH4 begins to decrease with the increase of pore size,and the effect of N2 replacement to drive out CH4 is obvious when the pore size is 4 nm.