Microfluidic Investigation of Salinity-Induced Oil Recovery in Porous Media during Chemical Flooding
Microfluidic Investigation of Salinity-Induced Oil Recovery in Porous Media during Chemical Flooding
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DOI：
10.1021/acs.energyfuels.0c04320
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发表时间：
2021-03-02
期刊：
影响因子：
5.3
通讯作者：
Shin, Sangwoo
中科院分区：
文献类型：
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作者：
Park, Sung Wan;Lee, Jonghyun;Shin, Sangwoo
高、低矿化度水驱是油田从油藏中提取原油的常用采油工艺。这些过程通常依次进行，自然地在多孔地下建立不均匀的盐度。本文研究了高、低矿化度水驱油时矿化度变化对多孔介质中石油运移的影响。当我们从实际油藏的三维成像中观察到大量不透水的死角时，我们发现这些区域在石油开采中起着重要的作用，在这些区域中，石油的运移受盐度变化而不是流体动力学的控制。高矿化度水驱引起的矿化度梯度通过非平衡效应为困在死角区油滴的运移提供了途径。然而，在临界盐度以上，我们观察到液滴的快速聚集，导致孔隙空间完全堵塞，从而抑制了石油的采收率。我们还发现，在中等盐度下，水滴聚集适度，聚集反而促进了石油的采收率。我们的观察结果表明，在化学驱过程中，存在最大限度提高原油采收率的最佳矿化度条件。
High and low salinity water flooding are common oil recovery processes performed in the oil fields for extracting crude oil from the reservoir. These processes are often performed sequentially, naturally establishing non-uniform salinity in the porous subsurface. In this article, we investigate oil transport in porous media induced by salinity change upon flooding with high and low salinity water. As we observe a large number of impervious dead-ends from three-dimensional imaging of the actual reservoir, we identify that these areas play an important role in oil recovery where the oil transport is governed by the salinity change rather than hydrodynamics. The salinity gradients induced upon high salinity water flooding provide pathways to enhance the transport of oil drops trapped in the dead-end regions via non-equilibrium effects. However, above a critical salinity, we observe a rapid aggregation of drops that lead to the complete blockage of the pore space, thereby inhibiting oil recovery. We also find that, at an intermediate salinity where the drop aggregation is modest, the aggregation rather promotes the oil recovery. Our observations suggest that there exist optimal salinity conditions for maximizing oil recovery during chemical flooding.