Abstract:
Fractures serve as the primary storage space and seepage pathways for CO
2 geological storage, directly influencing storage efficiency and long-term containment security. This study employed UAV oblique photogrammetry to construct a discrete fracture network (DFN) model of a fractured sandstone reservoir within the Ordos Basin. Subsequently, a fluid-solid coupling numerical model for CO
2-water two-phase flow was established using the multiphysics simulation software COMSOL Multiphysics, explicitly accounting for the matrix-bedding-fracture system. Key findings reveal that CO
2 preferentially migrates along high-permeability bedding planes and fractures. Horizontal bedding, combined with low-dip, low-connectivity natural fractures, impedes vertical seepage, thereby reducing the risk of CO
2 escape into the caprock. The fracture network accelerates pressure transmission, inducing significant displacement responses. The initial rate of displacement increase was found to be 6.2 times higher than that observed in the matrix model. Consequently, accurately representing the multi-porosity system encompassing the matrix, bedding, and fractures is crucial for assessing the stability of CO
2 geological storage.