Lattice Boltzmann simulation of immiscible fluid displacement in porous media: Homogeneous versus heterogeneous pore network
Lattice Boltzmann simulation of immiscible fluid displacement in porous media: Homogeneous versus heterogeneous pore network
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DOI：
10.1063/1.4921611
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发表时间：
2015-05-01
影响因子：
4.6
通讯作者：
Valocchi, Albert J.
中科院分区：
文献类型：
--
作者：
Liu, Haihu;Zhang, Yonghao;Valocchi, Albert J.
将人为二氧化碳(CO2)注入地质构造是减少大气中温室气体排放的一种很有前途的方法。预测二氧化碳的捕获量及其在地下的长期储存稳定性，需要对孔隙尺度上的多相驱替现象有一个基本的了解。本文用格子Boltzmann方法模拟了非润湿流体在两个微流体流动单元中的非混溶驱替，一个单元具有均匀的孔隙网络，另一个单元具有随机的非均匀孔隙网络。我们已经确定了三种不同的驱替模式，即稳定驱替、毛细指进和粘性指进，它们都强烈依赖于毛细管数(Ca)、粘度比(M)和介质非均质性。研究发现，非润湿流体饱和度(S-NW)随非润湿流体与润湿流体的粘度比(M)的增大而近似线性增加，增大M或降低介质非均质性均可增强驱替过程的稳定性，导致S-NW的增大。在任一孔隙网络中，比界面长度与排水过程中的S-北西向成线性关系，除表现出相当粘性指进的情况外，所有情况下的比例常数相等。我们的数值结果证实了先前的实验发现，无论是有利的(M>；=1)还是不利的(M<；1)位移，稳态比界面长度与S-NW呈线性关系，而对于不利的位移，斜率略高。(C)2015年作者(S)。除另有说明外，所有文章内容均按照知识共享署名3.0未移植许可进行许可。
Injection of anthropogenic carbon dioxide (CO2) into geological formations is a promising approach to reduce greenhouse gas emissions into the atmosphere. Predicting the amount of CO2 that can be captured and its long-term storage stability in subsurface requires a fundamental understanding of multiphase displacement phenomena at the pore scale. In this paper, the lattice Boltzmann method is employed to simulate the immiscible displacement of a wetting fluid by a non-wetting one in two microfluidic flow cells, one with a homogeneous pore network and the other with a randomly heterogeneous pore network. We have identified three different displacement patterns, namely, stable displacement, capillary fingering, and viscous fingering, all of which are strongly dependent upon the capillary number (Ca), viscosity ratio (M), and the media heterogeneity. The non-wetting fluid saturation (S-nw) is found to increase nearly linearly with logCa for each constant M. Increasing M (viscosity ratio of non-wetting fluid to wetting fluid) or decreasing the media heterogeneity can enhance the stability of the displacement process, resulting in an increase in S-nw. In either pore networks, the specific interfacial length is linearly proportional to S-nw during drainage with equal proportionality constant for all cases excluding those revealing considerable viscous fingering. Our numerical results confirm the previous experimental finding that the steady state specific interfacial length exhibits a linear dependence on S-nw for either favorable (M >= 1) or unfavorable (M < 1) displacement, and the slope is slightly higher for the unfavorable displacement. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.