A new model describing the interaction between fluid pressure wave in pores and P-wave in rock matrix

Abstract

The interaction between seismic waves in rocks and fluid pressure in pores remains one of the most challenging topics in seismic exploration. A perturbation technique is used to develop a new model to describe the propagation of fluid pressure in pores associated with P-waves in the rock matrix. The basic idea is to approximate classification of waves in saturated rocks into two orders. The first order is a dominant P-wave in the matrix, and the second order is a companion fluid wave induced by the first-order wave. This approach is innovative and advantageous in that the complex interactions of stress between the matrix and fluid are decoupled and the mathematical solutions become easy to seek for. The fluid pressure wave is analyzed by a 1D plane wave ignoring the Poisson’s effect. Parameterization of the model using sandstone saturated with water results in the conclusion that the fluid wave has an amplitude one order of magnitude smaller than the matrix wave and the two waves have a very slight phase difference. We have also evaluated the potential application of our model to shale gas and shale oil.