Pore‐Scale Explanation of the Archie's Cementation Exponent: Microstructure, Electrical Anisotropy, and Numerical Experiments

Abstract

Abstract Electrical anisotropy of rock is a key parameter in geophysical research. In this paper, digital rocks were constructed by aligning elliptic grains to create samples with anisotropic pore connectivities. Lattice gas automata are used to research electrical transport properties for revealing the anisotropy and physical meaning of Archie's cementation exponent. Simulated results indicate that the relationship between formation factor and porosity is of anisotropy with the exponent corresponding to the change rate of pore complexity with porosity, instead of pore complexity itself, confirming previous theoretical studies. Besides, the results reveal that anisotropy of pore structure is a main factor leading to the anisotropic relation. Under the effects of fracture, there is a U‐shape transition zone over a range of porosity for anisotropy exponent. Moreover, the simulated data are in good agreement with the laboratory experiments, which can further verify the validity of the results.