Multiple Fracture Propagation Model for a Three-Dimensional Hydraulic Fracturing Simulator

摘要

Multiple nonplanar hydraulically induced fractures are often observed or assumed to exist in well stimulation sites of petroleum and geothennal reservoirs. Although such multiple and nonplanar features of the fractures affect the fracture extension and well stimulation efficiency, or even cause failure of the fracturing treatments, most of the available numerical simulators for hydraulic fracturing place restrictions on the fracture geometry such as a single, planar, and symmetrical fractures. To develop design tools and investigate the nature of fracture formation in consideration of the interaction between each fracture, the authors developed a true three-dimensional simulator of the fracturing process. The stress field around a fracture induced by the entire fracture system is computed and used to determine fracture aperture and its advance. The displacement discontinuity method is used to model arbitrary shapes of fractures with a fully coupled solution of fracture deformation and injected fluid pressure under the condition of mass conservation. In this paper, the theoretical basis and numerical method are presented with some examples of the simulated results for multiple fractures.