Abstract：Rock physics theory plays an important role in the estimation of elastic modulus and velocity. Dry rock skeleton elastic modulus is the key parameter for calculating saturated rock elastic modulus and velocity. Differential equivalent medium theory is the theoretical basis for calculating dry rock skeleton equivalent modulus. Because of the coupled equations, it is difficult to obtain its exact analytical solution and we usually only obtain an approximate numerical solution. Based on predecessors' research results, we assume that dry rock skeleton modulus ratio is a linear function of porosity. With the polarization factor expressions, we decouple the coupled differential equivalent equations to ordinary differential equations, and build a new dry rock skeleton equivalent model. Analytical solution derived in this paper can efficiently calculate the equivalent modulus of dry rock skeleton compared with numerical simulations. In the end, tests on Han's experimental data and real logging data show that the proposed approach can effectively estimate rock P- and S-waves' velocity.
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