The Time-shift Polarization Analysis In VSP Three-component Detection Data

Multi-wave and multi-component seismic exploration technology has been widely used in seismic exploration. VSP three-component records can provide richer information of seismic than each single component. The record is about full wave-field three-dimension vector information. Using the polarization properties of seismic waves to study the wave-field information provides a new application method for VSP wave-field separation and processing.The thesis content is mainly about analysis of time-shift polarization, which based on the polarization characteristics of VSP three-component, three-component seismic exploration polarization analysis and VSP polarization analysis. Details are as follows:(1) The content has described the basic theories and methods of VSP three-component polarization analysis and has reviewed the traditional VSP polarization analysis.(2) The superiority-inferiority of time-shift and time-invariance has been compared and analyzed. Traditional time-invariance VSP three-component could get good results in horizontal location. However, due to the polarization properties of seismic wave is time-shift, there are many problems in application of separation of P and SV wave in actual processing such as it can't separated the wave-field incorrectly.(3) On the basis of accomplishing the energy criterion analytical method and covariance matrix analytical method to compute the polarization angle. In order to meet the needs of time-shift polarization analysis, characteristics of the VSP three-component obser-vation and the different polarization conditions, two sets of the projection formula about separation and synthesis of wave-field were derived. The traditional energy criterion and covariance matrix were applied to analysis of VSP time-shift polarization successfully, and got good test results.(4) The method of estimation of polarization in mixed wave-fields by Cho and Spencer was introduced to VSP three-component analysis. That method is more accurate and effective in makeing polarization analysis and synthesis in two different waves of the mixed wave-fields.(5) With the programming tools, we built several time-shift polarization analysis methods. Through comparing result of theoretical data and practical data, we verified the applicability of various methods and the accuracy of procedures.(6) Finally, we summarized analytical method of energy criterion, the applicable condition and superiority-inferiority of covariance matrix and the method by Cho and Spencer. In order to do better, we put forward ideas and direction of improvement.