Modeling reactive flow dynamics of gelled acid in fracture-vuggy carbonates: a coupled thermal-hydrological-chemical simulation

Abstract

In engineering, gelled acids play a crucial role in facilitating reactive flow phenomena across diverse mediums. This study undertakes a comprehensive numerical investigation into the reactive flow dynamics within fracture-vuggy carbonates, employing gelled acid as the agent. The mathematical model intricately couples thermal, hydrological, and chemical aspects to provide a holistic understanding of the process. Fractures are meticulously modeled using a pseudo-fracture approach, while vugs are delineated as highly porous matrix clusters. The simulation meticulously examines the influence of vugs and fractures, in conjunction with the rheological behavior of gelled acid, on the dissolution process. Our findings reveal that compared to hydrochloric acid, gelled acid is more effective in treating high-temperature carbonate rocks. A lower power law index induces a more pronounced response in shear stress, resulting in a more uniform dissolution pattern. Moreover, the presence of vugs and fractures exerts a significant impact on both the trajectory of wormhole growth and its penetration depth. As the length of fractures increases and their number multiplies, their dominant influence on the growth of wormholes becomes more pronounced. Furthermore, an abundance of fractures may attenuate the influence of vugs. This study highlights the importance of controlling the power-law index and understanding the complex interactions between fractures and vugs for reactive flow.