Enhancing Cluster Efficiency by Modeling Swelling Diverter Particles in PKN-Type Fractures

Uneven fracture propagation stemming from reservoir heterogeneity, nonoptimal design, and stress interference significantly affects cluster efficiency in unconventional reservoirs. While the use of diverter agents in field to mitigate overgrown or less stimulated fractures holds promise, a thorough comprehension of the underlying mechanisms remains crucial. This work presents a coupled simulator that integrates a PKN-type fracturing model with a particle transport model to address the challenges of uneven fracture propagation in unconventional reservoirs. By combining nonlocal elasticity for stress interaction, a global tip asymptotic solution for multiscale tip behavior, and Eulerian-Eulerian method for particle transport and bridging, the simulator provides a robust framework for modeling field-scale particle diversion. The model includes particle swelling and dissolution characteristics to enhance fluid diversion effectiveness. The simulator replicates field treatment procedures, incorporating sequential additions of a fluid pad, diverter particle slug, and proppant-laden slurry. Numerical examples demonstrate its capability to achieve uniform non-propped lengths in viscosity-dominated propagation regimes and equal propped lengths in transition propagation regions. This tool optimizes pumping schedules and applies particle diversion technology to improve cluster efficiency during stage fracturing, enabling the design of optimal procedures for enhanced field performance. 1. INTRODUCTION The heterogeneous nature of formations, coupled with nonoptimal well completions and stress interference, often results in unequal stimulation among clusters during stage fracturing (Rafieepour et al., 2020; Soliman et al., 2008; K. Wu & Olson, 2015; Zheng et al., 2019). This disparity in fracture growth leads to production variability substantiated by production logs (Cipolla et al., 2011; Miller et al., 2011). To counter this, fluid diversion techniques have emerged as a mitigation strategy by modifying or redirecting fluids toward less stimulated fractures. Field-tested applications have demonstrated the effectiveness of this approach (Evans et al., 2016; Fragachán et al., 2016; Gomaa et al., 2016; McCartney & Kennedy, 2016; Ugueto et al., 2020). Diverter agents, strategically placed at various locations such as perforation inlets, perforation tunnels, fracture entrances, and fracture tips, serve this purpose (Daneshy, 2019).