Investigation of temporary plugging agents transport and plugging behavior in fractures using CFD-DEM coupling method

Intra-fracture temporary plugging fracturing is an effective technique for the creation of multi-level branched fractures. The transport and plugging performance of temporary plugging agents (TPAs) within fractures directly determines the efficiency of the fracturing operation. However, there are few studies addressing the growth mechanisms of the plugging layer, and the influence of key TPA physical properties (such as particle shape and friction coefficient) on plugging efficiency remains poorly understood. This lack of understanding hinders the theoretical foundation necessary for the optimized design of intra-fracture temporary plugging strategies. In this study, a high-fidelity numerical model based on a coupled CFD–DEM approach, which accurately accounts for particle–particle contact and collision behaviors, was developed to simulate the transport and plugging process of TPAs within fractures. A comprehensive investigation was conducted to understand the plugging behavior under varying operational parameters. The results indicate that the growth of the plugging layer follows four distinct stages, different operational parameters primarily influence the growth characteristics by altering the particle sedimentation rates at the front and rear of the accumulation zone. An increase in friction coefficient enhances bridging capability and results in a 74.07 % reduction in plugging layer length. Small-diameter TPAs (1.2 mm) exhibit poor plugging performance due to their low bridging probability, which can be improved through synergistic injection of mixed particle sizes. Irregular-shaped particles form interlocking structures via multi-point contacts, enhancing the mechanical stability of the plugging layer. An optimal TPA density range of 1120–1300 kg·m⁻³ is recommended.