Flow Simulation of Artificially Induced Microfractures Using Digital Rock and Lattice Boltzmann Methods

Energies

S.Hossein Hejazi¹  Linda Luquot²  Jingsheng Ma³  ToussaintDono Ngarta⁴  Zhihui Liu⁴  Jun Yao⁴  Lei Zhang⁴  Yongfei Yang⁴ 

[1] Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta T3A 6C9, Canada;Hydrosciences Montpellier, Université Montpellier, CNRS, IRD, 300 Avenue du Pr. Emile Jeanbrau CC57, 34090 Montpellier, France;Institute of Petroleum Engineering, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, UK;Research Centre of Multiphase Flow in Porous Media, China University of Petroleum (East China), Qingdao 266580, Shandong, China;

关键词: CT;    digital rock;    microfractures;    Lattice Boltzmann method;    pore-scale simulations;   

DOI  :  10.3390/en11082145

来源: DOAJ

【 摘 要 】

Microfractures have great significance in the study of reservoir development because they are an effective reserving space and main contributor to permeability in a large amount of reservoirs. Usually, microfractures are divided into natural microfractures and induced microfractures. Artificially induced rough microfractures are our research objects, the existence of which will affect the fluid-flow system (expand the production radius of production wells), and act as a flow path for the leakage of fluids injected to the wells, and even facilitate depletion in tight reservoirs. Therefore, the characteristic of the flow in artificially induced fractures is of great significance. The Lattice Boltzmann Method (LBM) was used to calculate the equivalent permeability of artificially induced three-dimensional (3D) fractures. The 3D box fractal dimensions and porosity of artificially induced fractures in Berea sandstone were calculated based on the fractal theory and image-segmentation method, respectively. The geometrical parameters (surface roughness, minimum fracture aperture, and mean fracture aperture), were also calculated on the base of digital cores of fractures. According to the results, the permeability lies between 0.071–3.759 (dimensionless LB units) in artificially induced fractures. The wide range of permeability indicates that artificially induced fractures have complex structures and connectivity. It was also found that 3D fractal dimensions of artificially induced fractures in Berea sandstone are between 2.247 and 2.367, which shows that the artificially induced fractures have the characteristics of self-similarity. Finally, the following relations were studied: (a) exponentially increasing permeability with increasing 3D box fractal dimension, (b) linearly increasing permeability with increasing square of mean fracture aperture, (c) indistinct relationship between permeability and surface roughness, and (d) linearly increasing 3D box fractal dimension with increasing porosity.

【 授权许可】

Unknown