Experimental study on the displacement patterns and the phase diagram of immiscible fluid displacement in three-dimensional porous media
Experimental study on the displacement patterns and the phase diagram of immiscible fluid displacement in three-dimensional porous media
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DOI：
10.1016/j.advwatres.2020.103584
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发表时间：
2020-06-01
影响因子：
4.7
通讯作者：
Suekane, Tetsuya
中科院分区：
文献类型：
--
作者：
Hu, Yingxue;Patmonoaji, Anindityo;Suekane, Tetsuya
在地下开采过程中，由粘性力和毛细力的平衡控制的不混溶流体驱替模式对采收率或储存效率具有显著影响。位移模式的相图已经被广泛研究的二维（2D）微观模型，但三维（3D）多孔介质的关注很少。本文利用X射线显微层析成像技术，在孔隙尺度上研究了在较宽的毛细管数Ca和粘度比M范围内，疏松填充床中的非混相排驱。在三维多孔介质中观察到三种典型的驱替模式，即粘性指进、毛细指进和稳定驱替模式。三种位移模式在Ca-M图上的大致位置与二维微观模型中的研究结果一致。三个区域的边界是基于饱和度分布作为Ca和M的函数的定量分析确定的。与二维细观模型的结果相比，三维多孔介质中不同区域之间的过渡区更宽。应用指状结构的分形维数和指状结构宽度表征了不同驱替模式下注入流体侵入孔隙和喉道的机理。毛管指的平均分形维数为2.58 ± 0.05，与侵入渗流理论定义的2.55一致。对于粘性指进，其中粘性力主导侵入过程，侵入流体沿与注入方向相同的多个优先流动路径，并且指宽仅为1至2个孔隙体。此外，还比较了连续注入条件下典型粘性指状物和毛细管指状物的侵入动力学。这项研究可能会提高我们的理解，在三维多孔介质中的粘性/毛细作用力共同支配的驱替过程的动力学。此外，各种条件下的相图（即广泛的Ca和M）可以帮助找到适合地下过程的储层条件。
The immiscible fluid displacement pattern, controlled by the balance of viscous and capillary forces has a significant effect on the recovery or storage efficiency in subsurface processes. The phase diagram of displacement patterns has been extensively studied for the two-dimensional (2D) micromodel; however, that of the three-dimensional (3D) porous media has received little attention. This work experimentally studied the immiscible drainage displacement in an unconsolidated packed bed at the pore scale with a wide range of capillary number Ca and viscosity ratio M using X-ray micro-tomography. Three typical displacement patterns, namely viscous fingering, capillary fingering, and stable displacement, were observed in 3D porous media. The rough location of three displacement patterns on the Ca-M diagram was consistent with previous studies in 2D micromodel. The boundaries for three regimes were determined based on the quantitative analyses of the saturation distribution as functions of Ca and M. Compared with the result in 2D micromodel, a broader transition zone between different regimes was found in 3D porous media. The characterizations of finger structures (e.g. fractal dimension and finger width) were applied to reveal the mechanism of how the injected fluid invades the pores and throats inside porous media for different displacement patterns. The average fractal dimension of capillary fingerings was 2.58 +/- 0.05, which agrees with the 2.55 defined by the invasion percolation theory. For the viscous fingering, where the viscous force dominates the invasion process, the invading fluid follows a several preferential flow paths in the same direction as the injection and the finger width was only 1 to 2 pore bodies. Besides, the invasion dynamics under continuous injection conditions were compared for typical viscous and capillary fingerings. This study may improve our understanding of the dynamics of displacement processes jointly governed by the viscous/capillary forces in 3D porous media. Furthermore, the phase diagram under various conditions (i.e. a wide range of Ca and M) can help to find a suitable reservoir conditions for subsurface processes.