Numerical Modeling of Fracture Propagation during Temporary Plugging and Diverting Fracturing

Summary The temporary plugging and diverting fracturing (TPDF) technique has proved to be effective in enhancing reservoir stimulation volume and increasing oil and gas production. However, the mechanisms influencing the propagation behavior of diverted fractures under induced stress fields remain unclear. In this study, we establish a numerical simulation model considering fluid-solid coupling effects based on the discrete element particle flow method for TPDF. The model can simulate the fracture diverting propagation pattern and the evolution of the induced stress field around the fracture after temporary plugging near the wellbore. The numerical simulation results, in good agreement with analytical solutions and experimental data, validate the correctness of the numerical model. We analyzed the induced stress effects on the propagation behavior of diverted fractures based on this model, and investigated the impact of horizontal stress differences and fracturing fluid viscosity on the morphology of diverted fractures. The simulation results reveal that after the diverted fracture initiates, an X-shaped strong compressive stress zone forms around the fracture. The diverted fracture propagates along the depression in the area of strong compressive stress (i.e., in the direction where the compressive stress is the weakest). The expansion of diverted fractures causes a stress reversal at the tip of the initial fracture, leading to its reopening. As the horizontal in-situ stress difference increases, the tensile effect at the tip of the diverted fractures gradually weakens, and the deflection amplitude of the diverted fracture toward the initial fracture direction gradually increases. Fracturing fluid seepage significantly influences the propagation behavior of diverted fractures and induced stress fields. When the viscosity of the fracturing fluid is low, the diverted fracture tends to deviate more significantly toward the direction of the initial fracture. Choosing high-viscosity fracturing fluid and reservoirs with a smaller horizontal stress difference for TPDF operations is conducive to enhancing reservoir stimulation volume. The study results contribute to understanding the fracture propagation mechanisms of TPDF, providing theoretical support for the design of TPDF construction schemes.