Numerical Simulation of Adaptive Plugging Using Novel Knotted Balls in Horizontal Wells

Summary Novel knotted temporary plugging balls have been widely applied in various fields, owing to their unique geometric structure. The optimization of temporary plugging in multicluster horizontal wells is a critical challenge for enhancing hydraulic fracturing efficiency. For this study, we developed and experimentally validated a computational fluid dynamics-discrete element method (CFD-DEM) coupled model to simulate the migration and plugging behavior of novel knotted temporary plugging balls. An innovative discrete ball-chain method was introduced to characterize the flexibility of fibrillated tails, while the immersed boundary method (IBM) was applied to directly resolve fluid/solid interactions. The simulation results revealed a three-stage plugging mechanism comprising axial migration, adaptive alignment, and compliant deformation. In the second stage, the critical capture distance between the ball and perforation is defined as the key parameter governing successful plugging. The tail structure significantly extends this distance, which scales with the tail length and number. Plugging placement can be steered by adjusting the density contrast between the tails and the core. Furthermore, multicore knotted balls exhibited self-adaptive selective and secondary plugging under nonuniform erosion. Based on these findings, a variable-density multicore adaptive plugging strategy is proposed that integrates low-, medium-, and high-density designs to improve the perforation plugging probability in multicluster completions. The results provide guidance for material design and operational optimization.