A Study Of Seismic Abnormal Wave Imaging Technology

In the case of complex structures under local conditions,such as the existence of pinchouts,sections,holes,and so on,there will be abnormal waves(such as cross-section waves,diffraction waves,etc.)in the seismic records.They are caused by the underground complex geologic structures and are the effective waves to understand the underground anomal information.However,the existing imaging technique is to treat the abnormal waves and the reflection waves simultaneously.The result is that the seismic imaging resolution is reduced and the geologic information carried by abnormal waves is not used effectively.Therefore,in order to make full use of this kind of abnormal waves to solve the complicated geological problems,this paper,starting from the abnomal waves exploration theory,studies the seismic abnomal waves imaging technology,which aims to solve the geological problems by extracting and imaging the abnormal waves separately.Based on the analysis of the causes,propagation regularity and seismic response characteristics of abnormal waves,this paper focuses on the research work of abnormal waves extraction,imaging velocity modeling and migration imaging with two groups of geologic models.In the study of abnormal waves extraction,the median filter and mean filtering method are used to extract anomalous waves in the common shot set,common offset set and stack profiles,and the feasibility and effectiveness of the two methods are analyzed.In the study of abnormal waves migration imaging,the important parameters of prestack time migration(migration aperture and migration angle)were studied.In this paper,the speed model of abnormal waves imaging is studied,the initial velocity model is obtained by combining the reflection velocity scanning with the imaging velocity analysis,and then the abnormal waves prestack time migration velocity model is established by means of the same phase axis leveling and fine pickup speed.The process of prestack abnormal waves imaging processing is established,and the feasibility of Kirchhoff prestack time migration imaging processing is validated by numerical model processing.Furthermore,a set of 2D actual seismic data with abnormal waves are dealt with,and the anomalous geologic information is obtained more abundant than the traditional reflection waves method.The combined use of reflection imaging and abnormal waves imaging results can make full use of the information carried by seismic waves to solve the geological problems.