Rock physics relations are used as a bridge between the petrophysical and calculated elastic properties of rock in order to investigate seismic properties, prediction of well-log or to create rock physics types. In this article, which corresponds to one of the sandstone oil reservoirs located in Persian Gulf, the theoretical-contact Hertz-Mindlin has been used to calculate the elastic properties of dry rock in one wells of the field. The results of this model was compared with those obtained by the direct method (Gassmann model). Considering to the partial cementation of reservoir, the improved average limits of Hashin-Shtrikman model made by Hertz-Mindlin theory is suitable to calculate the dry bulk modulus of the rock in the this well. The average limits of Hashin-Shtrikman model that improved by Hertz-Mindlin theory can also be used to calculate shear wave modules with 0.01 friction coefficient.