The attenuation of P wave in a periodic layered porous media containing cracks
Guohua Wu · Chinese Journal of Geophysics · 2014
The attenuation and dispersion of seismic wave will occur because of the fluid flow of different scales in the porous medium when the seismic wave propagates in saturated medium.We build a periodic layered porous media containing cracks by introducing two kinds of microscopic squirt-fluid mechanism for the coin-shaped and pinchout-shaped cracked porous medium into the layered-White model based on the attenuation mechanisms of macroscopic Biot flow and mesoscopic local flow,we then solve the poroelastic equations using the Dutta' s mathematic techniques which make equations uncoupled for solutions to get the attenuation and dispersion velocity of P wave of the model and compare with the results of the layered-White model.The characteristics of attenuation and dispersion of P wave for the model are analyzed with the change of the parameters of the two kinds of cracks,namely crack density and crack aspect ratio,and the content of cracks.With the increase of the crack density of the coin-shaped and pinchout-shaped cracked porous medium,the influence on the attenuation and velocity of P wave increases.When the crack aspect ratio increases,a portion of attenuation of P wave moves to the higher frequency band.When the content of the crack decreases,which means that the crack density and aspect ratio reduces,the peak of attenuation of P wave decreases firstly and then increases,finally decreases again,and the velocity of P wave increases.The results finally approach to that of the layered-White model.Finally,we study the low and high frequency limit of the model and the character of the relative displacement of the model containing coin-shaped cracks.