ABSTRACT

We have developed a novel method for Q estimation. As a seismic wave propagates through subsurface viscoelastic media, seismic attenuation decreases the amplitude and reduces the bandwidth, which leads to variation of the logarithmic spectral area of seismic wave. According to this property, we have derived an analytical relation between Q factor and the logarithmic spectral area difference of seismic wave. To improve the accuracy of Q estimation, we took account of the amplitude loss due to energy partitioning from transmission. Tests of the method on synthetic models determined the validity of our method, and it was insensitive to different types of noises and evaluated density. A further comparison between the presented method and two widely used Q estimation methods, namely, the logarithmic spectral ratio and centroid frequency shifting methods, with a synthetic model containing random noise demonstrated that our method is the more robust, in these situations, among the three approaches. Then, we also compared the effect of bandwidth and time-window selection on the Q estimation for these three methods, and the result revealed that our method is less sensitive to the bandwidth and time window than the other two methods. Application of this method to real zero-offset vertical seismic profile data shows a reasonable correlation between estimated interval-Q and interval velocities, which further indicates the validity of the method.

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