Numerical simulation method for multi-stage hydraulic fracturing based on modified dilation-recompaction model

Multi-stage hydraulic fracturing in horizontal wells has been proven an effective stimulation method to enhance well performances from extremely low permeable reservoirs by creating a complex fracture network. The concept of stimulated reservoir volume (SRV) was introduced to quantify the complex fracture network. Knowledge of the SRV is important for the evaluation of the hydraulic fracturing performance and the estimation of hydrocarbon recovery. However, it is still a challenging topic to model the evolution of the SRV and estimate its properties because of the presence of fluid–solid complex interactions during the fracturing process. Most current SRV estimation methods are complex and computationally expensive. The paper applied a simple modified dilation-recompaction model to simulate the evolution of the effective SRV without representing the fracture geometry explicitly. By history matching production data of a multi-stage fractured horizontal well in Chang 8 formation of the YanChang oilfield, China, the calibrated dilation-recompaction model can successfully characterize the evolution of the generated SRV and estimate the rock properties of the fractured zones. The simulation results show that the total effective stimulated reservoir volumes amount to 88,375 m3. The shape of a fracture zone is nearly elliptical about 54 m wide and 20 m high surrounding a well perforation. The permeability of the zone reaches as high as 28 mD, centering around the wellbore and decreasing gradually outward.