A New Multi-Cluster Fracturing Simulation Model Coupled with Perforation Erosion: Based on the Continuous–Discontinuous Method

Promoting uniform propagation of multiple fractures in horizontal wells is significant to increase the stimulated volume of unconventional reservoirs. However, the stress interference between multiple fractures and the perforation erosion caused by slurry fluid greatly affect the uniform propagation of multiple fractures. In this paper, a new multi-field coupled fracturing model that can simultaneously consider stress-seepage-fracture-erosion is developed based on the continuous–discontinuous element method (CDEM). The model is verified by the Khristianovich–Geertsma–de Klerk model (KGD), displacement discontinuity method (DDM), and finite-element model (FEM). The base case is used to investigate the effect of perforation erosion on multiple fractures’ propagation. And the effect of flow rate and perforation parameters (perforation diameter and perforation number) on perforation erosion and multi-fractures propagation are discussed. The results show that perforation erosion will unevenly increase the perforation diameter and perforation discharge coefficient, and the flow rate is redistributed among multiple fractures, aggravating the uneven propagation of multiple fractures. Furthermore, the advantage fractures are more affected by erosion than the suppressed fractures. When the flow rate is from 9 m3/min to 12 m3/min, the effect of erosion significantly increases and leads to a larger increment of perforation diameter and perforation discharge coefficient. Different combinations of perforation parameters also have great effects on perforation erosion and multi-fractures’ propagation. Reducing the perforation number and perforation diameter will significantly increase perforation friction. The advantage fractures are transformed into the suppressed fractures and the suppressed fractures are transformed into the advantage fractures by the adjustment of high perforation friction. Simultaneously, the smaller perforation number and perforation diameter lead to a larger increment of perforation diameter and perforation discharge coefficient, and a faster and larger decrease of the perforation friction. This study can provide some guidance for the optimization and design of multi-fractures’ uniform propagation.