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Accurate formulae for P-wave reflectivity and transmissivity for a non-welded contact interface with the effect of in situ vertical stress.

Authors :
Chen, Fubin
Zong, Zhaoyun
Yin, Xingyao
Feng, Yanwen
Source :
Geophysical Journal International. Apr2022, Vol. 229 Issue 1, p311-327. 17p.
Publication Year :
2022

Abstract

A detailed knowledge of wave reflectivity parametrization for non-welded interface plays an important role in fracture characterization and reservoir prediction. However, the effect of in situ stress on reflectivity formulae for non-welded contact interface remains unclear. Here based on the linear-slip theory and acoustoelasticity theory, we propose the accurate P -wave reflectivity and transmissivity formulae for planar P wave incident upon the non-welded interface between two elastic half-spaces under the in situ vertical stress. The discontinuous boundary conditions coupled with vertical stress is used to represent the non-welded contact interface for the elastic and viscous cases. Then accurate formulae are derived by solving the boundary conditions. Numerical results show that the proposed formulae are frequency-dependent and the non-welded interface performs as high- and low-pass filters for reflected and transmitted P wave at low stress, respectively. Moreover, initial vertical stress can change the maximum amplitudes of reflection and transmission coefficients and the corresponding critical angles. Particularly, vertical stress weakens the fracture-induced anomalous seismic reflections in zones lack of significant impedance contrasts at low incidence angles. The sensitivity analysis suggests a non-welded interface transforms into a welded interface at normal compliance |${\Delta _N} \le 5 \times {10^{ - 11}}$|  m Pa−1. The phases and amplitudes of the four coefficients reach the maximum values at the specific viscosity |$\eta \approx {10^6}$|  Pa·s m−1 for the case of P wave obliquely incident upon the viscous interface at incidence angle 30°. Finally, we describe a method for simulating seismic reflection at the interface of two elastic media with experimental measurement. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
0956540X
Volume :
229
Issue :
1
Database :
Academic Search Index
Journal :
Geophysical Journal International
Publication Type :
Academic Journal
Accession number :
155931710
Full Text :
https://doi.org/10.1093/gji/ggab475