多尺度多孔介质酸岩化学反应微观流动模拟
Abstract
<p indent="0mm">The chemical reactions between minerals and fluids leading to dissolution phenomena are of great research significance in various fields, such as enhanced oil and gas recovery, soil and water quality protection, and CO<sub>2</sub> safe storage. To clarify the dissolution process in multi-scale porous media under acid-rock reactions, this study utilizes the Darcy-Brinkman-Stokes equation to couple free flow and seepage flow during the reaction process. It also establishes mineral mass conservation equations and acid fluid mass conservation equations during the reaction, considering the mass exchange caused by chemical reactions. Based on the ideal model, different dissolution patterns and dissolution diagrams are obtained under various injection velocities, surface reaction rates, and diffusion coefficients. In the conical wormhole dissolution model, the core normalized permeability increases the fastest due to the strong traceability of the main wormhole channels. When Pe (Peclet)≤0.01065, the core exhibits a face dissolution pattern, where diffusion is the primary mechanism for solute transport, and convective transport is insufficient to initiate wormhole formation. When Da (Damköhler)≤0.1065, Pe≥0.1065, and Pe is more than 50 times Da, the dissolution process is controlled by Da, and uniform dissolution is observed in the lower-right corner of the dissolution diagram. Combining CT and SEM-Maps for the micro-reaction flow simulation of two real digital cores, the results show that micro-cracks promote the dissolution of minerals near the wall, with permeability increasing by nearly 2.85 times.</p>
