超临界CO_2在岩石孔隙内流动状态的分子模拟

本文采用分子模拟的方法研究了地质封存条件下超临界CO_2在镁橄榄石孔隙内的流动,分析了孔隙尺寸、温度、压强对超临界CO_2的密度分布和流动速度的影响.研究结果表明,只有当孔隙尺寸大于5.0 nm时,超临界CO_2分子在岩石孔隙内的流动才符合Poiseuille流动;同时,超临界CO_2分子在岩石近壁面存在1.5 nm的密度震荡,当孔隙尺寸小于15 nm时,密度振荡现象会影响CO_2分子在岩石孔隙内的平均密度;升高温度、降低压强的方法可以减小密度震荡的第一峰值,减弱岩石壁面与CO_2的相互作用,使得CO_2的流动速度增加.

Molecular Dynamics Study on Flow of Supercritical CO2 in Rock Pores

Molecular dynamics (MD) simulation was applied to investigate the flow of supercritical CO2 in forsterite pores under geological storage. The effects of pore size, temperature and pressure on the density distribution and flow velocity of supercritical CO2 in rock pores were analyzed. The results showed that only when the pore size of forsterite is larger than 5.0 nm, the flow of supercritical CO2 in the pores can accord with Poiseuille flow. And the density oscillation of supercritical CO2 is 1.5 nm near the rock wall. When the pore size is less than 15 nm, the density oscillation will affect the average density of CO2 in the rock pores. The method of increasing temperature and decreasing pressure can reduce the first peak value of density oscillation, weaken the interaction between rock wall and CO2, and finally increase the flow velocity of CO2.