Optimization of the shale gas reservoir fracture parameters based on the fully coupled gas flow and effective stress model

Abstract

Abstract Fracture parameters are important for oil and gas production. In this paper, we establish a fully coupled gas flow and effective stress model for the single well multi‐stage hydraulic fracturing shale gas reservoir and analyze the optimal fracture parameters of this model. Firstly, the reservoir consists of single‐porosity medium zone, dual‐porosity medium zone, and hydraulic fracture zone. Then, on the basis of the effective stress mechanism, the theory of porous elastic medium, evolution of fractal dimensions, and the mechanism of fluid transportation, we establish an apparent permeability model of matrix and fracture system to couple the deformation of reservoir and gas flow in matrix. After that, the partial differential equation is solved by COMSOL and verified using the field shale gas production data of Barnett and Marcellus. Finally, the model is used to optimize the fracture parameters. The results show that by increasing the half‐length of hydraulic fracture, the gas production gets the maximum growth, followed by increasing the fracture diversion capacity and width of hydraulic fractures. For the shale gas reservoir with large‐fractured and relatively high permeability, increasing the length of hydraulic fractures can bring higher production, while for the micro‐fractured and low‐permeability, hydraulic fractures with complex shapes can contribute to production increase.

Keywords

• apparent permeability
• fluid‐solid coupling
• fracture property
• numerical simulation
• shale gas reservoir