Development of particle method formalism for numerical modeling of the response of fluid-saturated porous geological materials

Abstract

The authors have generalized the mathematical formalism of hybrid particle method (method of hybrid cellular automata) for the numerical simulation of deformation and fracture of fluid-saturated porous geological materials at the meso- and macroscopic scales. The formalism allows taking into account inelastic deformation, dilatancy and fracture of solid skeleton as well as the influence of pore pressure on skeleton stress state and the fluid redistribution in pore space of the fractured geological medium. In the framework of the model the mechanical response of the skeleton is described within the model of plasticity of geological medium with unassociated flow law. The redistribution of the gas phase is simulated by numerical solution of equations of filtration and diffusion. The adequacy of the formalism is illustrated with the results of the theoretical study of gas pore pressure influence on coal sample strength under uniaxial compression. It is shown that the degree of pore pressure influence on macroscopic strength of gas-saturated material is strongly determined by the ratio of parameters of strength criterion, which reflects the content of defects and damages of high rank in the solid skeleton.

Keywords

• fractured porous geological medium
• fluid
• numerical modeling
• cellular automaton method
• particle method
• plasticity