SEISMIC VELOCITY ANOMALY RECOGNITION METHOD AND ITS APPLICATION BASED ON FINE ITERATIVE MODELING

Abstract: Lateral velocity anomalies and their distribution patterns and intensities in a region affect the time-depth conversion strategy for the region, and, therefore, the accurate description of the lateral velocity anomalies will directly affect the reliability of the time-depth conversion. The conventional method uses the difference between the original migration velocity and the well interpolation velocity volumes to identify the velocity anomaly, and the precision is rather low. In this paper, a residual velocity analysis method based on constrained velocity inversion and AVO update criteria is adopted to improve the accuracy of seismic velocity field，and the method of velocity anomaly identification and decompacting along layers used to accurately describe the lateral velocity anomaly. Practical application shows that the method can effectively identify the distribution pattern of the lateral velocity anomaly for the bottom surface of the Minghuazhen Formation in the study area, give risk warning for regular time-depth conversion methods, effectively recommend variable velocity time-depth conversion strategy, and get better practical results.