CO2 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CO2 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CO2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CO2 驱替水的过程.结果表明,随着含水饱和度的增加,CO2 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CO2 注入过程而逐渐降低.研究认为含水饱和度是影响CO2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.
Numerical Simulation Study on Influence of Water Saturation on CO2 Breakthrough Pressure in Caprock
Geological injection and sequestration of CO2 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 CO2 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 CO2 was studied.In terms of methods,finite element software was used,and interpolation functions were set up to simulate the process of CO2 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 CO2 continued to increase,and a fitting exponential equation was established between the two.At the same time,the capillary pressure inside the core gradually decreased with the injection process of CO2.The study believes that the degree of water saturation plays a substantial role in determining the pressure at which CO2 breakthrough occurs,and provides a microscopic mechanism analysis of the change in capillary pressure,providing theoretical support for practical engineering practice.
CO2 sequestrationCaprock integrityBreakthrough pressureCapillary pressure
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