Accuracy of formation factors for three-dimensional pore-scale images of geo-materials estimated by renormalization technique

► The formation factor is a dimensionless electric resistivity of porous geo-materials. ► The renormalization is a promising technique to estimate the quantity quickly. ► Estimation accuracy for various 3-D CT images of real geo-materials was investigated. ► It was revealed that the accuracy significantly depends on the following parameters: ► Porosity; pore or grain size; pore anisotropy; initial subsystem size.