Molecular simulation of CH_(4)/CO_(2)/N_(2)ternary mixture competitive adsorption and diffusion dynamics in tight sandstoneOA
Injecting impure CO_(2)for enhanced gas recovery(CO_(2)-EGR)offers a dual benefit by improving natural gas extraction while enabling CO_(2)sequestration.However,the interactions between CO_(2),N_(2),and CH_(4)under reservoir conditions require further investigation.This study employs Grand Canonical Monte Carlo(GCMC)and Molecular Dynamics(MD)simulations to quantify the adsorption and diffusion behaviors of CO_(2),N_(2),and CH_(4)in quartz nanopores over a pressure range of 1-24 MPa under varying water saturations and gas compositions.The results indicate that:(1)CO_(2)exhibits the broadest energy distribution and the strongest adsorption stability,occupying about 20%-30%more adsorption sites than CH_(4)or N_(2)and showing the least sensitivity to water saturation,with only a 30%reduction at 50%saturation,compared to 60%for CH_(4),giving CO_(2)a clear competitive advantage.(2)The adsorption and desorption behaviors are strongly pressure dependent,as increasing pressure reduces the adsorption layer area and shifts gas distribution from adsorption dominated to free phase.Competitive adsorption analysis reveals that while CO_(2)dominates displacement at low pressures,mixtures that contain N_(2)achieve higher CH_(4)desorption efficiency above 13 MPa by mitigating diffusion resistance.(3)A higher N_(2)fraction improves CH_(4)diffusion coefficients,thereby facilitating gas mobility and ensuring superior recovery performance under high-pressure conditions.This study advances the fundamental knowledge of microscale gas behavior in tight sandstones and supports the feasibility of impure CO_(2)injection as a practical strategy for sustainable gas production.
Shihao Xu;Cheng Cao;Yulong Zhao;Liehui Zhang;Qingping Li;Shouwei Zhou;Shaomu Wen;Yong Hu;Jinbu Li;Yunsheng Wei;Wei Xiong;Bowen Guan
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China Chongqing University Industrial Technology Research Institute,Chongqing 401329,China HuaiRou Laboratory,Beijing 101499,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China Institute of Carbon Neutrality,Southwest Petroleum University,Chengdu 610500,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China Institute of Carbon Neutrality,Southwest Petroleum University,Chengdu 610500,ChinaHuaiRou Laboratory,Beijing 101499,ChinaHuaiRou Laboratory,Beijing 101499,ChinaPetroChina Southwest Oil&Gasfield Company,Chengdu 610056,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China PetroChina Southwest Oil&Gasfield Company,Chengdu 610056,ChinaResearch Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi''an 710018,ChinaResearch Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,ChinaState Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China
能源科技
Competitive adsorptionDiffusion coefficientTernary mixtureTight sandstoneMolecular simulation
《Natural Gas Industry B》 2026 (1)
P.77-92,16
supported by the National Natural Science Foundation of China(Grant No.U23A2022)the National Natural Science Foundation of China(Grant No.52474047)the Natural Science Foundation of Chongqing(Grant No.CSTB2024NSCQ-MSX0951)the Natural Science Foundation of Sichuan Province(Grant No.2025ZNSFSC1357)the National Science and Technology Major Project(Grant No.2025ZD1404307).
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