交错网格有限差分法地震资料逆时偏移

发布时间：2018-03-06 23:28

本文选题：交错网格　切入点：有限差分　出处：《成都理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：为了更好地研究复杂构造和速度分布条件下地震资料的精确成像方法,本文首先介绍了偏移原理、传统偏移方法及逆时偏移的概念。针对逆时偏移波场递推计算和成像过程中的具体问题进行了探讨,推导了适合于交错网格有限差分法的速度-应力方程,建立了高阶交错网格有限差分格式,形成了波场计算递推计算方程。就逆时偏移中涉及的边界条件、成像条件、逆时偏移中假象的消除等问题进行了分析。衰减吸收边界条件使得位于边界的干扰反射得到了有效的消除,减少了对计算区域正常波场的影响。逆时偏移有效突破了地层倾角的限制,对横纵向速度变化剧烈的复杂模型成像效果显著提高,对处理陡倾构造和多断层等复杂地质情况的偏移问题具有良好的实用价值。缺点是逆时偏移计算量和存储量都比较大。讨论了逆时叠前偏移的成像条件,并选择互相关成像条件为该方法偏移处理的成像条件。在逆时偏移处理过程中,互相关成像条件能消除假象干扰,使成像噪音得到较好的压制。用对点脉冲、双曲线反射波记录进行了叠后偏移脉冲响应试验,试验结果验证了理论;将Marmousi模型作为叠后偏移的处理对象进行了试算;四川某工区的实际地震资料进行了偏移处理;随后进行了叠前偏移脉冲响应试验,以及理论模型的单炮道集录和多炮道集叠前逆时偏移试算,均取得了很好的成像效果,证明所用的方法具有较好的偏移效果和很强的可靠性。
[Abstract]:In order to better study the accurate imaging method of seismic data under complex structure and velocity distribution, the migration principle is introduced in this paper. The traditional migration method and the concept of inverse time migration are discussed, and the velocity stress equation suitable for the staggered grid finite difference method is derived. In this paper, a high order staggered grid finite difference scheme is established, and a recursive computing equation for wave field calculation is formed. For the boundary conditions involved in inverse time migration, the imaging conditions are obtained. Some problems such as the elimination of false image in inverse time migration are analyzed. The attenuation absorbing boundary condition can effectively eliminate the interference reflection at the boundary. The effect of inverse time migration on the normal wave field in the calculated area is reduced. The inversion migration effectively breaks through the limitation of the dip angle of the formation and improves the imaging effect of the complex model whose velocity varies dramatically in the horizontal and vertical direction. It has good practical value in dealing with the migration problem of steep dip structure and multi-fault, etc. The disadvantage is that the computation and storage amount of inverse time migration are relatively large. The imaging conditions of inverse time prestack migration are discussed. The cross-correlation imaging condition is chosen as the imaging condition for the migration processing of this method. In the inverse time migration processing, the cross-correlation imaging condition can eliminate the false image interference and suppress the imaging noise. The hyperbolic reflection wave record is tested by post-stack migration pulse response test, the experimental results verify the theory, the Marmousi model is used as the processing object of post-stack migration, and the actual seismic data in a work area in Sichuan are processed by migration. Then the pulse response test of prestack migration and the theoretical model of single shot gather record and multi shot gather prestack inverse time migration are carried out, and good imaging results are obtained. It is proved that the proposed method has good migration effect and strong reliability.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.44

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