Pressure impacts on the wave dispersion in fluid-saturated dual-porosity media

Abstract

Summary The knowledge of pressure-dependent wave dispersion in the fluid-saturated porous media helps to better understand the wave propagation in the high-pressure fields, being important for the safe drilling and the exploration of oil and gas reservoirs. However, the relevant theories still need to be elaborated. In this study, we propose a rock physics model to describe the nonlinear pressure dependence of wave dispersion of fluid-saturated dual-porosity media based on the Shapiro dual-porosity model, Gurevich squirt flow model, David-Zimmerman pore structure model and Liu’s rock physics model. The new model considers the nonlinear deformation of cracks and linear deformation of stiff pores caused by the elevating pressure. The wave dispersion induced by the squirt flow and global flow are incorporated in the center equations. Modelling results illustrate that the new model can better explain the laboratory measurements of the two sandstones than Liu’s model and David-Zimmerman model, especially at low-magnitude pressures. The elevating pressure significantly weakens the attenuation of three waves induced by squirt flow but has very faint effects of wave attenuation induced by the global flow. The reasonably agreement between the modelled velocities and the laboratory data of Fontainebleau, Vosges sandstones and Indiana limestone validate the proposed model.