Hydromechanical Simulation of Fracture Propagation and Reservoir Production with Multiscale Fractures.

Hydraulic fracturing is essential for assuring production from unconventional reservoirs with ultra-low permeability. The efficiency of hydraulic stimulation is strongly affected by geological discontinuities, such as faults, joints, and natural fractures. This study proposes robust numerical models for fully coupled hydromechanical simulation of the phenomena present in fracture propagation and fluid migration problems in fractured media. A novel mesh fragmentation technique with an intrinsic pore-cohesive zone approach is developed to simulate unrestricted hydraulic fracture propagation. The proposed method allows studying the effect of some primary parameters on hydraulic and natural fracture interaction. In a reservoir simulation, a 3D hydromechanical formulation for an enhanced dual porosity/dual permeability (EDPDP) model is combined with a discrete fracture model (DFM) to represent a fractured porous formation more realistically. The new model allows the study of the impacts of natural fractures with different orientations at multiple scales on the hydromechanical behavior of the reservoir. Finally, this research proposes a new methodology that integrates a robust fluid-driven fracture propagation model and reservoir simulation, improving the evaluation of production performance. We simulate several hydraulic fracturing scenarios for the assessment of cumulative reservoir production. We also study the effects of multiple length fractures on the hydraulically stimulated reservoir integrating EDPDP-DFM. The numerical results show that natural fractures form preferential paths of HF propagation, enhancing well–reservoir connectivity but reducing hydraulic fracture aperture by fluid leak-off. Fluid viscosity and injection rate control fracture opening, pressure, growth, and fluid leak-off. Finally, secondary fractures significantly impact the estimation of fluid drainage and pore pressure dissipation. Highlights: A new methodology to integrate a robust fracture propagation model and reservoir simulation. Discrete fracture and enhanced dual porosity-dual permeability models are combined to study the effects of fractures of multiple lengths on the hydraulically stimulated reservoir. A higher injection rate was more effective for lower fluid viscosity, enhancing fracture length and opening. Secondary fractures significantly impact the estimation of fluid drainage and pore pressure dissipation. [ABSTRACT FROM AUTHOR]