High-Order Finite Difference Method in Reverse-Time Migration with Variable Grids Based on PML Boundary Condition
详细信息
- 责任者：Guo Nianmin (School of Geosciences ; China University of Petroleum (East China) ; Qingdao 266555 ; China) ; Wu Guochen
- 刊名：Oil Geophysical Prospecting
- 出版年：2012
- 卷期：47(2)
- 关键词：地震勘探 ; seismic exploration ; 数据处理 ; data processing
- 页码：p.256-265
- 图表：10 illus., 33 refs.
- 分类号：1600
- issnNo：ISSN1000-7210
- isbnNo：CN13-1095/TE
摘要
The reverse-time migration solves two-way acoustic wave equation without equation decomposition.This migration method has the advantages of high precision,accurate phase and better rotating wave imaging without influences of lateral velocity changes and high angle.Reverse-time migration builds wavefield continuation operator by two-way wave equation.It performs forward continuation to obtain source wavefield in time domain,and reverse extrapolation to obtain receiver wavefield in time domain.Then it uses cross-correlation imaging condition to complete the migration.So numerical modeling is the key process for reverse-time migration.If the shallow layer is seawater or low velocity zone,smaller spatial grid size must be used for finite difference method to effectively suppress dispersion,and to ensure the precision of the simulated wavefield.But if small spatial grid size and small time sample interval are applied to the whole region,extremely great computer time and large memory space will be needed.So this paper derives the high-order finite-difference algorithm based on PML boundary condition with variable spatial grid size and variable time sample interval for wavefield extrapolation,which can ensure the accuracy of the simulated wavefield and the precision of the finial reverse time imaging results,and also can save computer time.The numerical data experiments demonstrate that the method is effective and feasible.