A fractal geometry-based model for stress-sensitive permeability in porous media with fluid-solid coupling

Abstract

The coupling behavior of fluid and solid strain is difficult to describe, making it challenging to characterize and accurately predict permeability changes of porous media in complex environments. In order to improve universality and reliability of the model, the comprehensive effects of factors such as solid particle detachment, fluid solid coupling, multiphase flow, and stress sensitivity on the permeability of porous media are fully considered, establishing a fluid structure coupling stress sensitive permeability model based on material mechanics and fractal theory. The model is validated through stress-sensitivity experiments and particle steadiness tests, as well as previous experimental data. Key findings include: (1) The increase in stress, porosity, and water saturation results in an increase in the applied pressure required for a sudden change in normalized permeability, while the rate of decrease slows down; (2) The increase in fractal dimension of tortuosity will increase applied pressure for sudden changes in permeability; (3) The larger the fractal dimension of movable solid particles, the higher the tortuosity of solid particles, the smaller the fractal dimension of solid particles, and the faster the normalized permeability reduction rate. This model provides theoretical guidance for accurately predicting the flow behavior and development of stress sensitive reservoirs.