Kang Qinjun, Zhang Dongxiao, Chen Shiyi, He Xiaoyi
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Mar;65(3 Pt 2B):036318. doi: 10.1103/PhysRevE.65.036318. Epub 2002 Mar 7.
In this paper, we develop a lattice Boltzmann model for simulating the transport and reaction of fluids in porous media. To simulate such a system, we account for the interaction of forced convection, molecular diffusion, and surface reaction. The problem is complicated by the evolution of the porous media geometry due to chemical reactions, which may significantly and continuously modify the hydrologic properties of the media. The particular application that motivates the present study is acid stimulation, a common technique used to increase production from petroleum reservoirs. This technique involves the injection of acid (e.g., hydrochloric acid, HCl, acetic acid, HAc) into the formation to dissolve minerals comprising the rock. As acid is injected, highly conductive channels or "wormholes" may be formed. The dissolution of carbonate rocks in 0.5M HCl and 0.5M HAc is simulated with the lattice Boltzmann model developed in this study. The dependence of dissolution process and the geometry of the final wormhole pattern on the acid type and the injection rate is studied. The results agree qualitatively with the experimental and theoretical analyses of others and substantiate the previous finding that there exists an optimal injection rate at which the wormhole is formed as well as the number of pore volumes of the injected fluid to break through is minimized. This study also confirms the experimentally observed phenomenon that the optimal injection rate decreases and the corresponding minimized number of pore volumes to break through increases as the acid is changed from HCl to HAc. Simulations suggest that the proposed lattice Boltzmann model may serve as an alternative reliable quantitative approach to study chemical dissolution in porous media.
在本文中，我们开发了一种格子玻尔兹曼模型，用于模拟多孔介质中流体的输运和反应。为了模拟这样一个系统，我们考虑了强制对流、分子扩散和表面反应的相互作用。由于化学反应导致多孔介质几何形状的演变，使得问题变得复杂，这可能会显著且持续地改变介质的水文特性。激发本研究的具体应用是酸压裂，这是一种用于提高石油储层产量的常用技术。该技术涉及将酸（例如盐酸、HCl、醋酸、HAc）注入地层以溶解构成岩石的矿物。随着酸的注入，可能会形成高导电通道或“虫孔”。用本研究开发的格子玻尔兹曼模型模拟了碳酸盐岩在0.5M HCl和0.5M HAc中的溶解情况。研究了溶解过程以及最终虫孔模式的几何形状对酸类型和注入速率的依赖性。结果在定性上与其他人的实验和理论分析一致，并证实了先前的发现，即存在一个最佳注入速率，在该速率下形成虫孔，并且使注入流体突破所需的孔隙体积数最小化。本研究还证实了实验观察到的现象，即随着酸从HCl变为HAc，最佳注入速率降低，相应的最小突破孔隙体积数增加。模拟表明，所提出的格子玻尔兹曼模型可作为研究多孔介质中化学溶解的另一种可靠的定量方法。
