Kirchhoff型动态聚焦波束偏移

发布时间：2018-04-08 16:20

本文选题：偏移成像　切入点：叠前深度偏移　出处：《吉林大学》2017年博士论文

【摘要】：Kirchhoff型波束偏移隶属于束偏移成像方法,该方法将地震数据在各个窗中心分解为不同方向的平面波,并对所有平面波进行单独成像,可以处理复杂介质中经常出现的多至走时问题,是一种兼顾成像精度与计算效率的偏移算法。但这一方法使用的射线束传播算子随着传播距离的增加波束宽度发散过快,从而影响了相关属性信息的计算精度,并有可能降低最终的偏移成像效果。针对上述问题,文中在Kirchhoff型波束偏移中引入了可控制束宽发散的射线束传播算子,提出了Kirchhoff型动态聚焦波束偏移,取得了下列研究成果:(1)将动态聚焦射线束引入到Kirchhoff型波束偏移中,在射线追踪过程中采用变化而非固定的过度参数,使得中心射线上每一点均对应束腰位置,以此来控制偏移成像方法中的射线束传播范围,解决原有射线束宽度随传播距离增加发散过快的问题。(2)给出了以虚走时为基础的权函数计算方法以保证Kirchhoff型动态聚焦波束偏移的成像效果。(3)通过考虑纵向高度差对局部平面波分解步骤中时移项的影响,削弱起伏地形对偏移方法的影响,将Kirchhoff型动态聚焦波束偏移扩展成为了复杂地表条件下的成像方法。(4)通过考虑各向异性介质中的动态聚焦射线束,将Kirchhoff型动态聚焦波束偏移扩展成为了可以适应各向异性介质的偏移成像方法。多个数值模型以及实际地震资料被用于验证这一偏移方法,测试结果表明:Kirchhoff型动态聚焦波束偏移具有较强的成像能力,当这一方法被扩展到复杂地表以及各向异性介质中时仍然可以取得良好的成像效果。
[Abstract]:The Kirchhoff beam migration belongs to the beam migration imaging method, which decomposes the seismic data into plane waves in different directions at the center of each window, and makes a separate imaging of all plane waves.It can deal with the problem of multiple travel time which often occurs in complex media. It is a migration algorithm which combines imaging accuracy with computational efficiency.However, the beam propagation operator used in this method diverges too quickly with the increase of the propagation distance, which affects the calculation accuracy of the related attribute information and may reduce the final migration imaging effect.Aiming at the above problems, a beam propagation operator, which can control beam width divergence, is introduced into Kirchhoff beam migration, and Kirchhoff type dynamic focusing beam migration is proposed.The following research results: 1) the dynamic focusing beam is introduced into the Kirchhoff beam migration, and the excessive parameters are changed rather than fixed in the ray tracing process, so that each point on the center ray corresponds to the waist position of the beam.In order to control the range of ray beam propagation in the migration imaging method,To solve the problem that the original beam width diverges too fast with the increase of propagation distance, a weight function calculation method based on virtual walking time is given to ensure the imaging effect of Kirchhoff dynamic focusing beam migration by considering longitudinal height difference.The influence on the time shift in the local plane wave decomposition,By weakening the effect of undulating topography on migration methods, the Kirchhoff dynamic focusing beam migration is extended to imaging method .Y4 under complex surface conditions by considering the dynamic focusing beam in anisotropic media.The Kirchhoff type dynamic focusing beam migration is extended to be a migration imaging method suitable for anisotropic media.Several numerical models and actual seismic data have been used to verify this migration method. The test results show that the dynamic focusing beam migration of the 1: Kirchhoff type has a strong imaging capability.When the method is extended to complex surface and anisotropic media, good imaging results can be achieved.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P631.4

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