A Study On The Behaviors Of Shale Gas And Oil In The Nanochannel Of Shale Matrix By Molecular Simulation

The rising worldwide energy demand and the gradual exhaustion of conventional oil and gas resources have been transforming the exploitation of oil and gas toward unconventional resources slowly.As the typical unconventional resources,the research on the exploration and exploitation of shale gas and oil are laid much emphasis globally.In this work,with the intention to give some theoretic supports for the industry of shale gas and oil,we studied the issues of the origin,diffusion mechanism and new exploiting technology of shale gas and oil.The main content of this thesis are as follows:(1).In face of the global warming caused by CO2 emissions,a new scenario,injecting CO2 gases to displace shale gas,is proposed to reduce the amount of CO2 emissions and improve the exploitation efficiency of shale gas.Grand Canonical Monte Carlo simulations are adopted to investigate the displacement of shale gas by CO2 and the sequestration of CO2 simultaneously in a modeled shale matrix.The shale model is validated through making a comparison between simulated and experimental data.We find that both the displacement amount of CH4 and the sequestration amount of CO2 increase with the CO2 injection pressure.When the CO2 injection pressure is kept to be fixed,the displacement amount of CH4 and the sequestration amount of CO2 go up with the pore size of the shale matrix,but the CH4 recovery rate decreased with pore size.Moreover,we suggest that the optimum operating condition of CO2 displacing shale gas is at the depth of 1 km,which provides significant guidance and reference for displacement exploitation of shale gas by CO2.(2).Given that a close relationship between the permeability and self-diffusion of shale oil,it is necessary to investigate the diffusion mechanism of shale oil in the nanochannel of shale matrix.We studied on the behaviors of shale oil in the nanochannel by molecular simulation.The influences of total organic content,temperature,pore size and oil molecular structure on the self-diffusion of shale oil in the nanochannel of shale matrix are investigated by us.It is found that the self-diffusion of shale oil increase with the total organic content and temperature.When the pore size is enlarged from 2 nm to 50 nm,the self-diffusion of shale oil is expanded about 108 times.The alkene in the shale oil could be explored more easily than aromatic hydrocarbon.It is hoped that these conclusions will provide useful reference and fundamentality for the exploration and exploitation of shale oil.