Numerical Experiments for Electrical Anisotropy of Digital Rock with Fluids

The anisotropic relationship between resistivity index and water saturation(I-Sw) has been investigated by numerical experiments of digital rock using Lattice Gas Automata (LGA). The digital rock with anisotropic pore connectivity can be constructed by aligning elliptic grains to mimic the ideal sedimentary sequence under the effects of hydrodynamic environment and diagenesis. The simulated results indicate that anisotropy of reservoir resistivity can be caused by the changes of water saturation during oil production due to the effects of injection on the distribution of fluids. Moreover, the anisotropy of resistivity index definitely dependents much more on the fluids distribution rather than the pore connectivity. A new scalar model had been developed by redefining a new resistivity index to avoid involving a complicated calculation of vector in anisotropic rock. The new model will reduce to Archie’s law in isotropic rock.