Investigation of Electrical Anisotropy with Digital Rock Models

The anisotropic Archie relation between formation factor and porosity(F-Phi) has been investigated by numerical experiments of digital rock using Lattice Gas Automata (LGA). The approach to constructing the digital rock by aligning elliptic grains is used to mimic the ideal sedimentary sequence under the effects of hydrodynamic environment and diagenesis, which can produce an anisotropic pore connectivity. The simulated results indicate that the electrical anisotropy of rock saturated with a saline solution can be caused by the anisotropic connectivity of the pore space under the effects of extra conductivity from the electric double layer on the surface of grains. Based on our research, a new anisotropic F-Phi relation is proposed to relate the porosity to the tensor of anisotropic resistivity by redefining the new formation factor. The validity of the new formula was further verified by its application in the anisotropic formation model.