Implementation of manifold coverage for 3D rock fracture network modeling and its application in rock permeability prediction

Fracture network modeling is an important prerequisite for studies on rock mechanical behaviors and perme-ability properties. At present, fracture patterns in most discrete fracture network (DFN) models are expressed by Euclidean geometries, which leads to distortion in describing complex fractured rocks. In order to solve this problem, a block texture synthesis method is proposed in this paper to generate multi-resolution two-dimensional (2D) DFN models for fractured coal. The results show that the generated multi-resolution 2D DFN models largely retain the fracture texture structure in the original exemplar. In addition, the concept of manifold coverage is adopted to optimize the 2D fracture image, and the three-dimensional (3D) texture-based DFN models are generated by the solid texture synthesis method from the optimized image. The results indicate that the 3D texture-based DFN models have good fidelity of natural fractures in fracture sets, orientation, density, roughness, fluctuation, aperture and connectivity from the perspective of geometric appearance. Comparison between the 3D DFN model with texture coverage and random coverage shows good consistency in fracture proportion, geometric pattern, and permeability properties. Therefore, the 3D DFN models based on random coverage provide a new idea for modeling fractured rocks and lattice models in numerical simulation of rock mechanical behaviors and permeability properties by various methods, such as RFPA2D/3D, FLAC2D/3D, and Lattice Boltzmann Method (LBM).

Automated summary

The study proposes a block texture synthesis method for generating multi-resolution two-dimensional DFN models for fractured coal, and three-dimensional texture-based models were generated from optimized images showing good fidelity. Comparison with random coverage shows consistency, providing a new idea for numerical simulation.