How the effective pore and grain shapes are correlated in Berea sandstones: Implications for joint elastic-electrical modeling

Abstract

Joint seismic-electromagnetic surveys are increasingly being used for understanding the subsurface. Valid rock-physics models are key for interpreting joint survey data. Such models should explore the cross-property relationship between the elastic and electrical properties and link the joint elastic-electrical correlations to the properties of various types of rocks of interest. However, although current differential effective medium (DEM) models have had great success in independently modeling the elastic and electrical properties of porous rock, they are not directly suitable for joint elastic-electrical modeling because the elastic and electrical DEM models describe the microstructures of the rocks in different ways. Based on dedicated laboratory measurements and theoretical modeling, we have investigated how the effective pore and grain shapes are correlated in two Berea sandstones. We determine that the effective pore aspect ratios inverted from the elastic properties exhibit a negative linear correlation with the effective grain aspect ratios obtained from the electrical inversion. The effective pore and grain aspect ratios are linked as an implicit function of varying porosity with confining pressure. Using the derived pore and grain shapes correlation, the joint elastic-electrical modeling results compared successfully with experimental data. The obtained results reveal the natural link between the effective pore and grain shapes in Berea sandstones and make the microstructures between the elastic and electrical models consistent.