Seismic quality factor estimation using prestack seismic gathers: A simulated annealing approach

Abstract

Fluid movement and grain boundary friction are the two main factors affecting the anelastic attenuation of seismic data. The quality factor ([Formula: see text]) quantifies the degree of anelastic attenuation and is commonly used in assisting the identification of gas reservoirs. We can accurately compute [Formula: see text] if we obtain the accurate amplitude spectrum of seismic wavelets at refereed and at target time indexes of the seismic profile. However, it is very difficult to obtain the accurate wavelets at the referred and target time indexes. Instead, we usually compare the changes of the amplitude spectrum of refereed and target seismic waveform. The seismic waveform is the convolution result between the seismic wavelet and the reflectivity series. Thus, the reflectivity series would affect our [Formula: see text] computation. We have assumed that the changes of the reflectivity series are negligible within one common-midpoint gather. Then the effect of relativity to the seismic spectrum is the same for the same seismic waveform at different offsets. The seismic waveforms at near offsets are treated as referred seismic signals, and the seismic waveforms at medium and far offsets are regarded as target seismic signals. We use simulated annealing to simultaneously obtain [Formula: see text] values at the entire time index of seismic traces. The method is applied to synthetic and real seismic data to demonstrate its validity and effectiveness. Both applications illustrate the effectiveness of the method in estimating seismic attenuation.