Study on the effect of natural fractures and temperature on the wormhole morphology formed by two-phase acidizing in carbonate rocks

The simulation of a two-phase acidizing process coupled with thermal–chemical–fracturing is a complex task, given the presence of natural fractures in carbonate rocks and the influence of temperature on the acid–rock reaction. In this work, we introduce a mixed computational strategy combining the operator splitting and the Newton iteration built upon the embedded discrete fracture model. This innovative strategy is designed to tackle nonlinear problems arising from the coupling of multiphysics fields. The porosity improved region within rock is divided into three parts: the high (H), medium (M), and low (L) efficiency regions, aimed at clearly assessing the impact of various physical fields on acidizing efficiency. The results show that the wormhole morphology is determined by the H and M regions, and the L region determines the acidizing efficiency. The oil in the rock can have a “sealing effect” on the acid, improving the acidizing efficiency. For the large fracture aperture, the wormhole morphology is predominantly influenced by fractures, with the influence diminishing as the aperture decreases. At small apertures, fractures exhibit minimal impact on the morphology. While increasing injection temperature may not significantly alter the wormhole morphology, it can enhance acidizing efficiency. The morphology of wormholes is highly sensitive to multiphase interactions, fractures, and temperature variations. The proposed hybrid computational strategy effectively addresses multiphysics field challenges in two-phase acidizing.