A novel construction approach for the pore structure model principally focuses on the controllable roundness of rock particles

Pores among particles provide the main space for the storage and migration of deep underground fluids (such as oil, gas, groundwater, and unconventional natural gas). The pores form a pore structure with complex morphology which is mainly dominated by the shape and distribution of particles. Therefore, the reconstruction of the pore structure or granular porous media and the evaluation of particle roundness have become an important foundation for the study of fluid flow through deep underground rock mass. This research proposes a novel approach for the multi-scale model with angular vertexes. The fractal topology theory and Voronoi space segmentation technology are combinedly used for the reconstruction of fractal granular porous media. The angular shapes are smoothed by using a modified B-spline technique and the particles with varying degrees of roundness are generated. To validate the superiority of our approach, the roundness based on the Wadell roundness calculation method is calculated and compared with the roundness obtained from particles smoothed using the vertex rounding substitution method. Results show that the roundness of particles smoothed with the modified B-spline technique closely aligns with the corresponding set rounded level (a nondimensional variable). Conversely, the vertex rounding substitution method is limited to a single dimensionally rounded radius. This innovative approach can offer a new method for the construction of granular porous media for the fluid flow study in deep underground rock mass.