Viscoelastic modeling and factor Q for reflection data

Abstract

Viscoelastic numerical models, based on a concept of dissipation mechanisms, take into accpunt memory variables, and some dissipation parameters, namely stress and strain relaxation times. In geophysical practice, the quality factor Q is widely used for describing an attenuation property of viscoelastic media. For numerical modeling, it is useful to know what dependence exists between the factor Q, and the relaxation times. Instead of deriving this dependence theoretically, in recent work, it is evaluated from results of numerical experiment for estimating the factor Q in synthetic reflection data. For obtaining the synthetic seismograms, a new 3D numerical model of wave propagation in viscoelastic media is developed, differing from previous ones by utilizing average values of relaxation parameters in cases of multiple dissipation mechanisms, and by applying a new modification of PML absorbing boundary. For the estimation of factor Q, numerical methods are used with manual choice of spectral windows. These methods are adapted for surface reflection data. The developed formula of the dependence Q on relaxation times is qualitatively good in a wide range of relaxation times.