385. 在咸水层中考虑重力、粘滞力和毛管力的CO2羽流迁移

CO2 Plume Migration with Gravitational, Viscous, and Capillary Forces in Saline Aquifers

本文研究了在咸水层中注入CO2时，为了调查实际流动情况，提出了一种无量纲组，该组以毛细管数和邦德数的组合形式，同时考虑了重力、粘滞力和毛管力三种力。单独使用每个无量纲组不足以获得与注入CO2流动行为的满意相关性。通过提出的无量纲组，得到了描述CO2注入速度、CO2-水界面张力和CO2与水的密度差异的CO2饱和度的通用剖面，从而分析了更现实的CO2流动行为。

CMG软件应用情况：

CO2羽流迁移分析使用了由计算机模拟软件集团开发的GEM-GHG组分模拟器。创建了一个二维垂直剖面系统的模拟模型，以考虑重力、粘滞力和毛管力。该系统是为CO2储存而设计的，三面有封闭边界，右侧有一个开口边界，以实现恒定压力边界条件，这使得CO2注入井没有压力效应，并且有利于CO2流动条件。

Fig. 1. Permeability distribution of system

Fig. 2. CO2 saturation distribution for various CO2 injection rate

Fig. 3. CO2 saturation distribution for various CO2-water interfacial tension

作者单位：韩国汉阳大学自然资源与环境工程系。

Abstract

In this study, we attempt to consider three forces of gravitational, viscous and capillary forces, simultaneously when CO₂ is injected in saline aquifers. In order to conduct it, we propose a dimensionless group in the form of combination of Capillary number and Bond number. This dimensionless group is a function of CO₂ saturation, in which the pattern of CO₂ flow regimes can be determined. By the analysis of the acquired each trapping mechanism from flow regimes, optimum CO₂ injecting scheme can be designed for maximizing the solubility and residual trappings as stable mechanism. With utilizing the proposed dimensionless group, we conducted several numbers of simulations using 2D vertical heterogeneous system with respect to CO₂ flow rate, interfacial tension between CO₂ and water, and brine salinity. From the simulation results, when gravitational and viscous forces with respect to capillary force are described by two individual dimensionless groups of Capillary number and Bond number, CO₂ saturation profiles are variously generated. These are not satisfactory correlations in the dependence of CO₂ saturation on Capillary number and Bond number for the variable terms of density differences between CO₂ and water and CO₂ injection rates. With the proposed dimensionless group, the universal profile of CO₂ saturation was obtained in describing CO₂ flow behaviors for the variables. Thus, considering two variables of density differences and CO₂ injection rates simultaneously, that is, when three forces considering at the same time, more realistic CO₂ flow behavior can be analyzed. This study helps to determine the most secure conditions of CO₂ injection and storage according to building the pattern of CO₂ flow regimes which is classified by the range of a dimensionless group.