Comparative analysis on pore‐scale permeability prediction on micro‐CT images of rock using numerical and empirical approaches

Abstract

Varieties of pore‐scale numerical and empirical approaches have been proposed to predict the rock permeability when the pore structure is known, for example, microscopic computerized tomography (micro‐CT) technology. A comparative study on these approaches is conducted in this paper. A reference dataset of nine micro‐CT images of porous rocks is generated and processed including artificial sandpacks, tight sandstone, and carbonate. Multiple numerical and empirical approaches are used to compute the absolute permeability of micro‐CT images including the image voxel‐based solver (VBS), pore network model (PNM), Lattice Boltzmann method (LBM), Kozeny‐Carman (K‐C) equation, and Thomeer relation. Computational accuracy and efficiency of different numerical approaches are investigated. The results indicate that good agreements among numerical solvers are achieved for the sample with a homogeneous structure, while the disagreement increases with an increase in heterogeneity and complexity of pore structure. The LBM and VBS solver both have a relative higher computation accuracy, whereas the PNM solver is less accurate due to simplification on the topological structure. The computation efficiency of the different solver is generally computation resources dependent, and the PNM solver is the fastest, followed by VBS and LBM solver. As expected, empirical relation can over‐estimate permeability by a magnification of 50 or more, particularly for those strong heterogeneous structures reported in this study. Nevertheless, empirical relation is still applicable for artificial rocks.

Effects of Pore Structure on Sandstone Mechanical Properties Based on Micro‐CT Reconstruction Model

“…As stated by Liu and Tang [42], Young's modulus is the slope of the elastic deformation stage (OA 1 , OA 2 , and OA 3 ) and the compressive strength is the value of points B 1 , B 2 , and B 3 . e volume modulus and shear modulus are obtained according to equations (6) and 7, respectively:…”

“…For the nontransparent rock with disorder and complex pore structure, the nondestructive and high-resolution CT technology has been used to acquire the 3D structure of the rock. e internal microstructure of the rock is quantitatively analyzed by the microscopic CT image [4][5][6]. In addition, the CT technology was also used to image the evolution of the rock microstructure under different loads.…”

Three‐dimensional Lattice Boltzmann simulation of gas‐water transport in tight sandstone porous media: Influence of microscopic surface forces

“…Xu et al simulated the pressure and velocity of the fluid flowing in fractures during the fracture deformation by Lattice Boltzmann and investigated the effect of the proppant size, sphericity, and the fracture width on the permeability and conductivity of hydraulic fractures. Song et al computed the absolute permeability of micro‐CT images by including the image voxel‐based solver, pore network model, LBM, Kozeny‐Carman equation, and Thomeer relation. Huang et al established a comprehensive apparent permeability model which couples the surface diffusion of adsorbed gas, slippage flow considering the additional flux generated by surface diffusion based on Langmuir's theory, and Knudsen diffusion.…”

Experimental study on stress sensitivity of high‐temperature and high‐pressure sandstone gas reservoirs in Yingqiong Basin

“…[29][30][31][32][33][34][35] A new stress-sensitive permeability analysis model was proposed by Zhu et al 36 And Zhu et al 37 thought the permeability performance under reservoir condition was divided into two stages through a semi-analytical model. The relationship between stress and permeability was studied through numerical simulation by Zhang et al 38 and Zhao et al 39,40 In addition, some scholars [41][42][43] have studied the changing of permeability in the production process.…”