3D imaging and flow analysis of sandstone pore structure

Abstract

Micro CT technology can provide three-dimensional high-precision digital images with micrometer (or smaller) resolution, offering robust technical support for the study of the internal structure of rocks. Based on the data obtained from the CT scanning of Leopard sandstone, a series of image processes were carried out using the Avizo software to extract pore distribution. The watershed algorithm was employed to independently segment each pore, and the largest sphere algorithm was used to establish a sphere-tube model. Based on the constructed pore network model, quantitative analyses of the porosity, fractal dimensions, permeability, and other parameters of the sandstone sample were conducted. Moreover, the connectivity of the pores was analyzed using an automatic skeleton model. Results show: ① CT scanning digital core technology can not only visualize the three-dimensional connectivity and isolated pores of sandstone but also quantitatively characterize the pore structure parameters; ② The analyzed Leopard sandstone has a connected porosity of 13.76%, an isolated porosity of 0.53%, and the pore radius is mainly concentrated in the 0-70μm small pore range, occupying 76.1% of the total pore volume; ③ The lower the sample porosity, the higher the fractal dimension, indicating a more complex pore structure.