Interval Q-factor Estimation from Zero-Offset VSP Data

Inelastic attenuation, quantified by Q, the seismic quality factor, has considerable impact on surface seismic reflection data. A new method for interval Q-factor estimation using near-offset VSP data is based on an objective function minimization measuring the difference between cumulative Q estimates and those calculated through interval Qs. To calculate interval Q, we use all receiver pairs that provide reasonable Q values. To estimate Q between two receiver levels, we use directly the equation that links amplitudes at different levels and can provide more accurate Q values than the spectral ratio method. To improve interval Q-estimates, which rely on travel times, we use a high-accuracy approach in the frequency domain to determine time shifts. Application of this method to real data demonstrates reasonable correspondence between Q estimates and log data.