Method Study Of Pre-Stack Wave Equation Depth Migration Methods Based On Irregular Topography

Pre-stack depth migration is an important method used to explore complex area. Under the condition of fair exact near surface velocity model, pre-stack depth migration from irregular topography directly is an effective method to deal with both the complex surface and the imaging of complex geological structures. During the nearest tens years, many people have done much study in this area, and there are methods such as wave-equation datuming, zero velocity method, wave field upward continuation etc.. A pre-stack depth migration method from irregular surface directly is prsented and programmed. And model test is done in detail. Chapter one shows the research actuality in this area, chapter two gives the detail of migration methods from irregular surface, chapter three shows the wave-equation pre-stack migration methods and the method propounded in this theses at large, including the processing flow. Model test results and results of real data are shown in chapter four, while the implication of this method in cross-well reflective wave pre-stack depth migration are shown in chapter five. And at the end, conclusions and view are drawn in chapter six. In conclusion, this method can eliminate the irregular surface's effect on imaging of subsurface structures fair well, and solve the'double complex'problem of both complex surface and complex subsurface structures at certain extent. Moreover, the method costs computing time almost the same of that of conventional pre-stack depth migration. All of these give us the fresh thought and new clew to the problem of migration in irregular topography area. Cross-well is emphasized for it high main frequency, and is used to study the connectivity of the layers between wells. Studying the similarity of the acquisition system of irregular surface seismic and that of cross-well seismic, a method used to do the pre-stack migration of cross-well reflection wave data including upward wave and downward wave is presented and programmed. What's more, we see great futurity in the migration results of the cross-well synthesized data.