Study on core modeling of carbonate rocks and dynamic characteristics of water invasion based on volume of fluid method

This study aims to investigate the dynamic behavior of water invasion fronts at the core scale to enhance the development efficiency of carbonate gas reservoirs. Using micro-computed tomography scanning experimental data, digital models of four distinct types of carbonate rocks with varying vuggy and fracture distributions were constructed. The water invasion process was simulated using the volume of fluid (VOF) method, allowing for a comprehensive analysis of water invasion front morphology and saturation curves. A novel parameter, the average characteristic front flow rate of water invasion (<i>q</i>*_front), was introduced, which correlates with water saturation and core porosity. The results demonstrate that low-porosity rocks exhibit uniform water paths, achieving high sweep efficiency and the lowest <i>q</i>*_front. In contrast, rocks with vugs and short fractures display unstable invasion paths due to uneven distributions, resulting in reduced sweep efficiency and higher <i>q</i>*_front. Rocks with extensive long fractures maintain fixed invasion channels but experience the lowest sweep efficiency, as their fronts advance the fastest with the highest <i>q</i>*_front. This study underscores the significant role of core-scale modeling and numerical simulation in optimizing carbonate gas reservoir development, while demonstrating their substantial potential in applications such as underground wastewater treatment and carbon dioxide geological sequestration.