Temporary plugging and diversion fracturing technology is an essential approach in the development of shale oil and gas. Enhancing the shear strength of temporary plugging zone is crucial for the success of this technology, which significantly depends on the geometric and mechanical characteristics of the plugging particle. Based on the rolling resistance model, this study uses Particle Flow Code (PFC) to establish a shear model for the temporary plugging zone. It explores the evolution of the strength of the plugging zone during shear failure through stress-strain curves. The research also reveals the mechanisms of strength variation from a microscopic perspective by integrating the force chain network structure. Furthermore, it quantitatively analyzes the influence of the friction coefficient, Young's modulus, and aspect ratio of the temporary plugging particles on the strength of the plugging zone. The results indicate that the strength of the temporary plugging zone is positively correlated with the strength of the force chains, but has a weaker relationship with the number of force chains. The greater the strength of the force chains, the higher the strength of the temporary plugging zone. The friction coefficient, Young's modulus, and aspect ratio of the particles are key factors affecting the strength of the force chains. As the friction coefficient, Young's modulus, and aspect ratio of the temporary plugging particles increase, the strength of the plugging zone initially increases and then stabilizes. The critical value for the friction coefficient is 1, for Young's modulus is 6.5 GPa, and for the aspect ratio is 2.7. The friction coefficient has the greatest impact on the strength of the plugging zone, followed by Young's modulus, while the aspect ratio has the least impact. This paper establishes a predictive model for the strength of the temporary plugging zone, clarifying the quantitative relationship between particle parameters and the strength of the plugging zone. It provides a basis for the optimal selection of particle materials and the development of new materials in the process of temporary plugging and diversion fracturing technology.
