A Novel Integrated DFN-Fracturing-Reservoir Model: A Case Study.

Core data from the hydraulic fracturing test site 2 (HFTS-2) show that a complex fracture network is created. In this work, a novel fracturing-reservoir simulator is applied to the HFTS-2 data to provide a thorough assessment of the impact of the fracture network on well performance. A methodology is also presented to effectively represent the dynamic propagation of hydraulic fractures in complex naturally fractured formations. First, data that characterize the natural fractures at HFTS-2 are used to create a realistic representation of the reservoir (a discrete fracture network, DFN). Then, a fracturing simulator that fully couples fluid flow, fracture mechanics, and a black oil reservoir simulator is used to first create the fracture network and then simulate flowback and production. A comparison of our simulation results with core data shows good agreement with the characteristics of the natural fracture network based on the post-frac core analysis. The production/flowback results are compared with the field results and are found to agree well with actual production data. While it is possible to use planar fractures to history match production, the results provide unrealistic fracture dimensions and reservoir drainage volumes. This directly impacts design and operational decisions related to well spacing and fracture size, which demonstrates the importance of incorporating realistic complex fracture networks into reservoir simulators for production evaluation and forecasting as well as fracture design and well spacing selection. Highlights: A novel integrated DFN-fracturing-reservoir model is developed that allows us to dynamically model hydraulic fracture propagation in a naturally fractured reservoir followed by multi-phase fluid flowback during production. The model allows us to assess the impact of the natural fracture network on well performance. Natural fractures are represented by a discrete fracture network (DFN), and the interaction of multiple hydraulic fractures with natural fractures is captured by the displacement discontinuity method (DDM). A methodology is presented to automatically calibrate pre-existing natural fractures with core data. [ABSTRACT FROM AUTHOR]