Theoretical study of the dielectric constant in porous sandstone saturatedwith hydrocarbon and water

Porous sandstone reservoirs generally consist of three components: sand gra in, hydrocarbon, and water, This paper proposes a hybrid method to predict the effective dielectric constant of such reservoir rocks using a combinati on of existing formulas and a simplified Fourier expansion method. Taking into consideration fluid distribution in pore space as well as pore structure, we have obtained the relations between the effective dielectric constant of sandstone and water saturation. The calculation results indicat e that the effective dielectric constant of sandstone varies as a function of the water saturation when porosity is above 10%, but it cannot predict w ell the hydrocarbon content in sandstone with low porosity (less than or eq ual to 10%). In this study, two different cases are discussed. In the first , mater is continuous and oil is in dispersed form in pore space, and in th e second, oil is continuous and water is as a dispersed phase in pore space . Very different results are obtained from the two distributions. In Case 1 , the effective dielectric constant approximately linearly increases with w ater saturation, but in Case 2, it is seen that a typical nonlinear relatio nship exists between the effective dielectric constant and water saturation . Furthermore, three models with microgeometry are considered, and the calc ulating result shows that the influence of geometry on the effective dielec tric constant is large.