Hierarchical Modeling of Hydromechanical Coupling in Fractured Shale Gas Reservoirs with Multiple Porosity Scales
Energy & Fuels, 35(7):5758 - 5776, 2021.
Summary
A hierarchical simulation strategy represents the different pore and fracture scales that govern gas production from shale. At the smallest scale, inorganic material and organic kerogen are homogenized into an equivalent medium. A second homogenization step incorporates natural fractures, while larger hydraulic fractures remain explicit through an embedded discrete fracture model. The resulting description combines multiple storage and transport mechanisms with deformation of the reservoir. Flow is discretized by a mimetic finite-difference method, and a stabilized extended finite-element scheme handles the mechanical problem. A sequential implicit solution procedure couples the two systems. Numerical examples first assess the method, followed by three-dimensional reservoir calculations that investigate the separate influences of inorganic matter, kerogen, natural fractures, and hydraulic fractures on gas production. The approach provides a way to retain effects of fine-scale structure without resolving every pore or natural fracture directly.