摘要
The Upper Triassic Xujiahe Formation in the western Sichuan Basin is featured by large burial depths over 300m,large thickness of surface subweathered zones(from tens to over 200m),rapid attenuation of high frequency signals of seismic waves,narrow effective band width,and low predominant frequency(25-30Hz) of seismic reflectance,resulting in a low accuracy of seismic reservoir prediction,especially for those thin sandstone reservoirs.In order to solve these problems,the stable Q-filtering technique that can simultaneously realize amplitude compensation and phase distortion correction is applied in the conventional seismic processing.Moreover,the stochastic seismic inversion by use of the Gamma-ray log is used to predict sandstone reservoirs based on the detailed reservoir calibration and correlation.These methods can effectively widen the amplitude at high frequencies up to 10-15 Hz while those at low frequencies are kept unchanged,in this way the recognition ability of thin sandstone layers and the accuracy of reservoir evaluation are both improved.