The Research And Application Of Reverse-time Migration In The TZ Area Of Sinkiang

With the development of seismic exploration, the land exploration work in Chinagradually turned to the complex near-surface structure and the complex undergroundgeological structure area. Reverse-time migration solve the two-way wave equation,can image the prism wave, turning wave and so on. It is the most addvanced seismicpre-stack depth imaging method. In this paper, We studied the application of pre-stackreverse-time migration(RTM) in practice data and velocity model building.Firstly, the paper briefly introduces three kinds of pre-stack depth migrationmethods which are Kirchhoff integration migration, one-way wave equation migrationand reverse-time migration. Then compare their advantages and disadvantages, solvethe two-way wave equation with high-order finite difference, discuss the stability anddispersion of finite difference, make a brief overview of the imaging condition ofRTM. All of these can supply the basis for the application of migration methods.Through the study on3-D pre-stack reverse-time migration processing in the TZarea of Sinkiang, We summarized the method of velocity model building for3-DRTM aiming at TZ area, the RTM processing flow aiming at the Ordovician strata ofTZ also has formed. The profiles after RTM processing have great improvementthan the old ones. In addition, through this processing project, I summarize somerecognitions and conclusions:(1)The velocity model building is the key of the pre-stack reverse-time migration.By using the union of pre-stack time migration, anisotropic velocity correction,Kirchhoff pre-stack depth migration and tomography, we determine a set of efficientand applicable method of modeling(2) The selection of parameters, such as migration aperture and steps, has a hugeeffect on the imaging performance, we should comprehensive consider the effect andcalculation efficiency factors. (3) Pre-stack reverse-time migration is not a single step, but a union of raw dataanalyzing, data preprocessing, velocity model building and migration imaging. All ofthese can affect the migration result, so the work of supervision and evaluation is ofgreat significance.(4) Pre-stack reverse-time migration is the advanced technology in solvingmigration imaging of geological complex areas; also it can provide a reliable basis forstructural interpretation and inverse analysis.