含水饱和度对盖层CO_(2)突破压力影响的数值模拟研究

Numerical Simulation Study on Influence of Water Saturation on CO_(2) Breakthrough Pressure in Caprock

CO_(2)地质注入与封存是减少大气温室气体排放的重要手段之一。为评估盖层完整性,必须确定不同条件下CO_(2)突破盖层的压力。基于气水两相渗流理论,建立岩心尺度模型,研究不同含水饱和度对CO_(2)突破盖层压力的影响。方法上,采用有限元软件,通过设置插值函数,模拟不同含水饱和度条件下岩心中CO_(2)驱替水的过程。结果表明,随着含水饱和度的增加,CO_(2)突破压力不断增长,两者之间建立了拟合指数方程。同时,岩心内部毛细压力随着CO_(2)注入过程而逐渐降低。研究认为含水饱和度是影响CO_(2)突破压力的关键因素,并对毛细压力的变化进行了微观机理分析,对实际工程实践提供了理论支持。

Geological injection and sequestration of CO_(2) is one of the important means to reduce atmospheric greenhouse gas emissions.To assess the integrity of the caprock,it is necessary to determine the pressure at which CO_(2) breaks through the caprock under different conditions.In this paper,a core-scale model was established based on the theory of gas-water two-phase seepage,and the effect of different water saturation on the breakthrough pressure of CO_(2) was studied.In terms of methods,finite element software was used,and interpolation functions were set up to simulate the process of CO_(2) displacing water in the core under different water saturation conditions.The findings indicated an escalating trend with the rise in water saturation,the breakthrough pressure of CO_(2) continued to increase,and a ftting exponential equation was established between the two.At the same time,the capillary pressure inside the core gradually decreased with the injection process of CO_(2).The study believes that the degree of water saturation plays a substantial role in determining the pressure at which CO_(2) breakthrough occurs,and provides a microscopic mechanism analysis of the change in capillary pressure,providing theoretical support for practical engineering practice.