A Laboratory-Scale DEM Simulation on Multiwell Simultaneous Fracturing to Improve the Understanding of Interfracture Interference

Abstract

As an emerging technology, simultaneous hydraulic fracturing has shown significant potential for increasing stimulated reservoir volume (SRV) in the development of shale gas. However, due to complicated interfracture interference mechanisms, its application is quite limited. In this study, a triwell simultaneous fracturing in shale gas reservoirs was modeled to explore the interaction laws between fractures as well as illuminate the formation conditions of complex fracture networks. The coupled fluid flow-Discrete Element Method (DEM) approach was used to simulate the initiation and synchronous propagation of hydraulic fractures. Also, the effects of far-field geostress difference, well spacing, injection procedure, and injection rate were investigated. Due to interwell and interfracture interference, complex fracturing initiation and propagation behaviors occur, and three interfracture interference mechanisms, including suppression, attraction, and repulsion, were observed. The stress shadow effect and far-field geostress state compete to influence fracture initiation, while well spacing also plays a key role. For a large far-field geostress difference, a small well spacing can improve the development of hydraulic fractures by increasing interfracture interaction. However, when a fracture preferentially initiates and propagates, it significantly suppresses the propagation of later emerging fractures, leading to poorly developed fractures. Therefore, appropriate injection procedures should be used to induce more complicated fracture networks.