发表机构
Imperial College London（帝国理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究结合微CT成像、孔隙网络分析等方法，揭示含烃碳酸盐岩中CO₂饱和盐水注入时，流场非均质性与反应物输送耦合形成溶解通道的机制，为CCUS储层反应运移预测提供关键依据。
AI 中文摘要
碳捕获、利用与封存（CCUS）是减少人为CO₂排放的关键途径。目前绝大多数封存的CO₂被注入枯竭的油气藏中。含烃碳酸盐岩储层中的反应运移不仅受反应物输送与表面反应之间平衡的控制，还受孔隙结构和流体分布形成的非均孔隙尺度流场的控制。本研究采用时间分辨微CT成像、孔隙网络分析和直接数值模拟，探究了以0.5 mL/min的速率将CO₂饱和盐水注入含油Ketton石灰岩时的通道化溶解过程。在180分钟的注入过程中，系统始终处于高佩克莱特数（Pe）、低达姆科勒数（Da）的 regime 中。尽管流动 regime 以平流为主，溶解仍呈现强烈的局部化特征：原始非均孔隙结构及残余油占据使盐水流动被限制在连通孔隙空间的一部分，形成了优先流动路径；溶解逐渐放大了这些路径，伴随的水力阻力降低进一步聚焦流动，最终在180分钟时形成连续的曲折通道。同时，有效反应速率仅为1.6×10⁵ mol/m²s，约为间歇反应速率的十分之一，表明在多相条件下，快速的平流输送并未直接转化为整体的快速溶解。这些结果表明，通道形成源于强反应物输送与孔隙尺度流场非均质性的耦合，而非仅由整体Pe-Da regime 决定。因此，考虑流场非均质性对于预测CO₂注入含烃碳酸盐岩储层时的反应运移及孔隙结构演化至关重要。
英文摘要
Carbon capture, utilization and storage (CCUS) is a key approach for reducing anthropogenic CO2 emissions. Currently the vast majority of CO2 stored is injected into depleted hydrocarbon reservoirs. Reactive transport in hydrocarbon-bearing carbonate reservoirs is controlled not only by the balance between reactant delivery and surface reaction, but also by the heterogeneous pore-scale flow field created by pore structure and fluid distribution. Here, we used time-resolved micro-CT imaging, pore-network analysis, and direct numerical simulation to investigate channelized dissolution during injection of CO2-saturated brine into oil-bearing Ketton limestone at 0.5 mL/min. The system remained in a high Pe, low Da regime throughout the 180 min injection. Despite the advection-dominated flow regime, dissolution became strongly localized. Preferential flow pathways were already present originally because the heterogeneous pore structure and remaining-oil occupancy restricted brine flow to a subset of the connected pore space. Dissolution progressively amplified these pathways. The associated reduction in hydraulic resistance further focused flow, producing a continuous tortuous channel by 180 min. Meanwhile, the effective reaction rate was only 1.6*10^5 mol/m2s,, approximately one order of magnitude lower than the batch reaction rate, showing that rapid advective transport did not translate directly into rapid overall dissolution under multiphase conditions. These results demonstrate that channel formation arose from the coupling between strong reactant delivery and pore-scale flow-field heterogeneity, rather than from the bulk Pe Da regime alone. Accounting for flow-field heterogeneity is therefore important for predicting reactive transport and pore-structure evolution during CO2 injection into hydrocarbon-bearing carbonate reservoirs.
