Estimation of Q-factor based on prestack CMP gathers and its application to compensate attenuation effects

Abstract

Summary Although prestack seismic data contains more abundant information in am plitude and traveltime than the poststack seismic data for estimating Q values, the waveforms or spectrum of reflectors are strongly altered by nearby reflectors or side lobes. It will interfere the calculation of spectrum and thus degrade the precision of Q estimation, several methods based on prestack data have been developed to solve this problem. Different from the usual, we propose a method based on the Modified S-Transform (MST) to estimate Q factor values from prestack CMP gathers. Q estimations can be obtained with regression analysis based on the relation of spectral ratio slope and the square of offset. Then, we utilize the resultant Q model to compensate the amplitude loss and correct phase distortion. Results from synthetic data and real data demonstrate that MST is more capable in improving the accuracy of Q value estimations. Applications on inverse Q filtering and prestack Q migration greatly improve the imaging resolution. While Q migration can obtain amplitude preserved gathers and corrects the phase to some extent, which contributes to better reservoir descriptions.