Stability of CO2-brine immiscible displacement
Stability of CO2-brine immiscible displacement
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DOI：
10.1016/j.ijggc.2012.07.001
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发表时间：
2012-11-01
影响因子：
3.9
通讯作者：
Ott, H.
中科院分区：
文献类型：
--
作者：
Berg, S.;Ott, H.
初级排水过程的粘性稳定性对于在咸水含水层中注入二氧化碳 (CO2) 至关重要，因为它决定了二氧化碳羽流在目标含水层中的扩散，从而决定了孔隙空间用于二氧化碳储存的初始利用。为了分析驱替过程的稳定性，必须已知相对渗透率饱和度函数；这些通常是通过在代表该领域的条件下进行的实验得出的。因此，不仅在现场尺度上而且在实验尺度上表征洪水前缘稳定性非常重要，以便判断实验结果的有效性，作为可靠现场模拟的前提条件。在这里，我们研究粘性指进的开始，从而研究在什么条件下CO2-盐水驱替保持稳定。我们通过数值模拟的方式讨论了不同长度尺度下相对渗透率的作用和毛细管压力的稳定作用。结果使我们能够评估流度比的不同定义，并建立判断驱替过程稳定性的标准。我们进一步表明，在重力很重要的情况下，重力舌在指法模式中占主导地位，并且仅通过考虑粘性力和毛细力就可以预测稳定性，从而可能发生不稳定情况。在文献中，已经提出了不稳定发生的各种标准，但这些标准是不一致或不确定的。我们的目的是让这次讨论井然有序。在本研究中，我们通过数值模型验证或反驳稳定性标准，并表明冲击锋移动率正确地描述了指法的开始。我们的研究结果的应用不仅限于二氧化碳盐水置换。稳定性标准可应用于油藏工程中的大多数两相流问题，从水驱到低界面张力表面活性剂驱。 (c) 2012 年 Shell Global Solutions International B.V. 由 Elsevier Ltd 出版。保留所有权利。
The viscous stability of the primary drainage process is of major interest for the injection of carbon dioxide (CO2) in saline aquifers, since it determines the spread of the CO2 plume in the target aquifer and consequently the initial utilization of the pore space for CO2 storage. In order to analyze the stability of the displacement process, the relative permeability saturation functions must be known; these are usually derived by experiments under conditions representative for the field. It is therefore very important to characterize the flood front stability, not only on the field scale but also on the experimental scale, in order to judge the validity of the experimental results as a precondition for reliable field simulations.Here we investigate the onset of viscous fingering, thereby studying under what conditions CO2-brine displacement remains stable. We discuss the role of relative permeability and the stabilizing effect of capillary pressure at different length scales by means of numerical simulations. The results allow us to assess different definitions of the mobility ratio and establish criteria for judging the stability of the displacement process. We further show that in cases where gravitational forces are important, the gravity tongue dominates the fingering pattern, and unstable situations can occur where stability would be predicted, by considering viscous and capillary forces only.In the literature various criteria for the onset of instability have been proposed, but these are inconsistent or inconclusive. Our intention is to bring order into this discussion. In the present study we validate or refute stability criteria by numerical modeling and show that the shock-front mobility ratio correctly describes the onset of fingering. The application of our findings is not limited to CO2-brine displacement. The criteria for stability can be applied to most two-phase flow problems in reservoir engineering in general ranging from water flooding to low interfacial tension surfactant flooding. (c) 2012 Shell Global Solutions International B.V. Published by Elsevier Ltd. All rights reserved.