孔隙尺度下超临界CO_2驱水两相流数值模拟

Pore-scale two-phase numerical simulation of supercritical carbon dioxide displacement of water

以咸水层封存二氧化碳(CO_2)为研究背景,利用流体体积函数(Volume of Fluid,VOF)多相流模型建立孔隙尺度多孔介质计算模型,研究了超临界二氧化碳(Sc-CO_2)注入到含水多孔介质中的两相运移规律。对比分析了毛细管数、地质封存压力、Sc-CO_2注射温度、两相表面张力系数、接触角等因素对两相运移速率以及驱替效率的影响,同时将不同毛细管数下的驱替效率与实验数据进行了对比。研究结果表明,随着毛细管数的增大,驱替效率先减小然后趋于稳定,数值模拟与实验数据吻合良好;在同一孔隙率下,在壁面表现为亲水性时,壁面润湿性越好,驱替速率越快,但驱替效率有所下降;同时毛细管数越小、地质封存压力越低、注射温度越高、张力系数越小驱替速率越快,且驱替效率越高。

The computational method of pore-scale porous media is established by using Volume of Fluid(VOF)numerical simulation method based on the background of CO2storage in Saline aquifer,and the migration mechanism of supercritical carbon dioxide(Sc-CO2)injection into porous media containing water is studied.The effects of capillary number,geological storage pressure,Sc-CO2injection temperature,two-phase surface tension coefficient and contact angle on the two-phase migration rate and the displacement efficiency were analyzed.At the same time,displacement efficiency was compared with experimental data under different capillary numbers.The result showed that with the increase of capillary number,displacement efficiency decreases first and then becomes stable,and the numerical simulation of displacement efficiency agrees well with experimental data under different capillary numbers.Under the same porosity,when wall surface is hydrophilic,wall surface wettability is better.The faster the rate of displacement,while the displacement efficiency decreased.At the same time,the lower geological storage pressure,the higher the injection temperature.Small surface tension coefficient has a higher displacement rate and efficiency.