Reflection and transmission coefficients of poroelastic thin-beds
Abstract
Based on Biot's poroelasticity theory for low-frequency range and Deresiewicz's boundary conditions, we first derive propagator matrices of multi-layered isotropic poroelastic media for elastic waves defined by displacement functions. Then we give the reflection and transmission coefficients of a thin-bed where there is only a fast P-wave incident. The reflection and transmission coefficients are functions of incidence angle, thin-bed thickness, frequency, Biot's elastic parameters and rock properties. Numerical simulations and comparisons with the solid-phase models show that, for models of a water-saturated thin-bed embedded by two water-saturated porous solid half-spaces, the reflections of fast P-wave, slow P-wave and converted S-wave versus incidence angle are of great difference. Not only do the thin-bed thickness and porosity affect the reflection coefficients' amplitudes and phases of the porous thin-bed, but also the existence of fluid further complicates amplitude-versus-angle characteristics of multi-waves. By comparison, the reflection characteristics of converted S-wave are more pronounced than those of fast and slow P-waves for small incidence. Meanwhile, slow P-wave reflections are sensitive to thin-bed thickness and porosity, which shows that an increasing thickness and porosity would result in a higher amplitude and a lower phase.
- Publication:
-
Journal of Geophysics and Engineering
- Pub Date:
- October 2018
- DOI:
- 10.1088/1742-2140/aac359
- Bibcode:
- 2018JGE....15.2209Y
- Keywords:
-
- thin-bed;
- propagator matrix;
- reflection and transmission coefficients;
- isotropic poroelastic media;
- displacement functions