Rock Physical Model of the Pressure Dependence of Elastic Moduli

Pressure strongly influences the mechanical, transport and elastic properties of rocks, such as acoustic velocity, porosity and elastic moduli. Seismic and borehole logging techniques measure these rock properties in order to infer subsurface information. To relate changes in seismic attributes to reservoir conditions, a thorough understanding of pressure effects on rock properties is essential. Therefore it is important to develop a petrophysical model based on simple physical assumptions which describes the relationship between Lamé constants as well as acoustic velocities and pressure. In this paper we present a rock physical model based on the idea that the pore volume of a rock is decreasing with increasing pressure to describe the pressure dependence of P and S wave velocities thereby the Lamé constants. Laboratory measured acoustic P and S wave velocities as a function of pressure - published in literature - are inverted to prove the applicability of the model and to obtain that of parameters. The quality checked joint inversion results showed that the calculated data matched accurately with measured data and also proved that the suggested petrophysical model performs well in practice.