Study on the Interaction Propagation Mechanism of Inter-Cluster Fractures under Different Fracturing Sequences

Abstract

Horizontal-well multi-cluster fracturing is one of the most important techniques for increasing the recovery rate in unconventional oil and gas reservoir development. However, under the influence of complex induced stress fields, the mechanism of interaction and propagation of fractures within each segment remains unclear. In this study, based on rock fracture criteria, combined with the boundary element displacement discontinuity method, a two-dimensional numerical simulation model of hydraulic fracturing crack propagation in a planar plane was established. Using this model, the interaction and propagation process of inter-cluster fractures under different fracturing sequences within horizontal well segments and the mechanism of induced stress field effects were analyzed. The influence mechanism of cluster spacing, fracture design length, and fracture internal pressure on the propagation morphology of inter-cluster fractures was also investigated. The research results indicate that, when using the alternating fracturing method, it is advisable to appropriately increase the cluster spacing to weaken the inhibitory effect of induced stress around the fractures created by prior fracturing on subsequent fracturing. Compared to the alternating fracturing method, the propagation morphology of fractures under the symmetrical fracturing method is more complex. At smaller cluster spacing, fractures created by prior fracturing are more susceptible to being captured by fractures from subsequent fracturing. The findings of this study provide reliable theoretical support for the optimization design of fracturing sequences and fracturing processes in horizontal well segments.

Research on the Interaction Mechanism of Multi-Fracture Propagation in Hydraulic Fracturing

“…After fracturing, the hydraulic fracture is not completely closed with the support of the proppant but will maintain a certain residual width, affecting the in situ stress field distribution. Previous multi-well fracturing numerical models did not consider the impact of these residual widths on the in situ stress field, resulting in deviations between the simulation results and the actual situation [31,32]. Especially in the case of repeated fracturing or infill well fracturing, the original stress field changes greatly, and previous hydraulic-fracturing calculation models cannot take into account the complex and uneven distribution characteristics of the stress field [33].…”