Modeling the effects of natural fractures on the permeability of reservoir rocks

• Ano de defesa: 2019
• Autor(a) principal: Fabbri, Heber Agnelo Antonel
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Fractured reservoir; Hydromechanical coupling; Barton-Bandis model; Interface finite elements with high aspect ratio; Reservatórios fraturados; Aclopamento hidromecânico; Model de Barton-Bandis; Elementos finitos de interface com elevada razão de aspecto
• Link de acesso: http://hdl.handle.net/11449/190698

This work presents a numerical method based on Discrete Fracture Model (DFM) and the Finite Element Method (FEM), where the fractures are approximated by a reduced model. The flow along and across the fracture is described by a simplified set of equations considering both conductive fractures and barriers. The coupled hydromechanical model is composed of a linear poroelastic Biot medium and a nonlinear model based on damage mechanics for the fractures, which captures the nonlinear normal deformation and shear dilation according to the Barton-Bandis model. Both flow and geomechanical models are approximated using the finite element model. Fractures are explicitly represented by three-node standard finite elements with high aspect ratio (i.e. ratio between the largest and the smallest element dimensions) and appropriate constitutive laws. These interface high aspect ratio elements represent a regularization method which continuously approximate the discontinuous pressure and displacement fields on a narrow material band around the fracture. The complete mathematical formulation is presented together with the algorithm suggested for its numerical implementation. The efficiency of the proposed method is demonstrated through numerical examples, as well as the effects of fractures in the hydraulic properties of porous rocks and its dependency of the stress state.