Research Of Wave Equation Datum Static Correction For Complex Topography Based On Grid

As we all know, static correction is the bottleneck in complex near-surface structure area all the time. The static correction methods broadly used in practice are all base on the Surface Consistency Hypothesis. But complex topography can't accord with the Hypothesis. So wave equation datum static correction is considered one of the best static correction method .In this paper, wave equation datum static correction is researched deeply, including implement flow, establishing near-surface velocity model and wavefield continuation. A reasonable implement flow is designed. An accurate velocity model is established. A high precision arithmetic of wavefield continuation is put forward. These makes wave equation datum static correction suitable for more complex topography, including rugged topography and velocity varying severely.Through deep analysis on the principle of wave equation datum static correction, a set of implement flow is designed. The flow includes nine steps:①Picking up refraction first break;②Obtaining near-surface structure by first break tomographic mothod;③Dividing seismic data into CSP gather and CRP gather ;④In CSP gather, continuating all receive points to the top of high velocity layer;⑤Continuating receive points to datum plane;⑥Resorting these data into CRP gather;⑦In CRP gather, continuating all shot points to the top of high velocity layer;⑧Continuating shot points to datum plane;⑥Resorting these data into CSP gather.The implement flow shows that wave equation datum static correction needs accurate near-surface structure and exact wavefield continuating arithmetic.First break can be picked through combinative method of automation and manual. Near-surface velocity model can be established through travel time inversion by shortest path ray tracing. The test result indicates that this method is correct and effective. Wave equation can be continuated by Kirchhoff approximation, finite-difference and method based on frequency-wavenumber field. Kirchhoff approximation and finite-difference aren't exact arithmetic. Exact result can be obtained in frequency-wavenumber field. Phase shift and phase shift with interpolating can't be used in most complex near-surface area, such as horizontal velocity varying acutely. In order to solve this problem,"phase-shift time-shift"arithmetic is proposed. The arithmetic modifies Stolt formula. Then, wave equation datum static correction can have arbitrary size correction.Many tests about the model and arithmetic are done, and practical seismic data of complex topography is processed. The result indicates that this implement project is correct. It can eliminate the bad influence of rugged topography and complex near-surface structure. Thus, it can establish a good foundation for velocity analysis and in-phase stacking.Wave equation datum static correction needs large computing resource. If the technology is applied into seismic data industry process, high computing environment is necessary. A computing cluster and a petroleum grid are built. Test result indicates this cluster has high efficiency. The program of wave equation datum static correction is migrated in grid.