Molecular dynamics simulations of helium transport through inorganic mineral nanopores  

作　　者：Dandan SONG Ping GUAN Chi ZHANG Jiahao REN 

机构地区：[1]School of Earth and Space Sciences,Peking University,Beijing,100871,China

出　　处：《Science China Earth Sciences》2025年第1期237-252,共16页中国科学(地球科学英文版)

基　　金：supported by the National Key Research and Development Program of China(Grant No.2021YFA0719000)。

摘　　要：Helium transport through nanoscale inorganic mineral pores and pore throats is essential for its overall migration.To elucidate helium's transport dynamics within nanopores,we employed equilibrium and non-equilibrium molecular dynamics simulations to investigate helium's static self-diffusion and pressure-driven flow in quartz slit-shaped nanopores.We also introduced water and various gases,including hydrogen,methane,ethane,nitrogen,and carbon dioxide,into the nanopores to assess their influence on helium transport.Our findings indicate minimal helium adsorption on quartz pore surfaces.Under conditions where the pore size is less than 5 nm and the pressure under 10 MPa,environmental factors markedly influence helium diffusion.Large pore sizes,high temperatures,and low gas pressures enhance helium desorption and facilitate faster diffusion.We observed a positive correlation between helium flow velocity and factors such as pore size,pressure gradient,and surface smoothness of the pores.Notably,the presence of pore water and carrier gases in quartz nanopores,which diffuse more slowly than helium,tends to reduce helium surface adsorption and slow its diffusion.Among the carrier gases studied,nitrogen showed similar adsorption capacity,diffusivity,and stability to helium,while carbon dioxide displayed the highest adsorption capacity and the slowest diffusion rate,markedly differing from helium.Based on the simulation results,we concluded that water and carrier gases primarily function as transport mediums in helium migration,moving together with helium.Nitrogen,which shares similar properties with helium,effectively assists in this co-migration process.Conversely,carbon dioxide,due to its high adsorption capacity and slow diffusion,tends to be lost during co-migration.As a result,gas reservoirs with high nitrogen levels and low carbon dioxide levels are more likely to have higher helium concentrations.Additionally,the smaller pore sizes and higher gas pressures in caprocks can impede helium's diffusion,favoring its pr

关 键 词：Helium transport Slit nanopores Molecular dynamics simulations DIFFUSION Flow carriers 

分 类 号：O64[理学—物理化学]