各向异性弹性波动态聚焦束逆时偏移

Anisotropic reverse time migration with dynamic focused beams for elastic wave media

1.中国石油化工股份有限公司胜利油田分公司物探研究院,山东东营257022;
2.中国石油化工股份有限公司胜利油田分公司油气勘探管理中心,山东东营257001;
3.中国地质大学(北京)地球物理与信息技术学院,北京100083

1. Geophysical Research Institute,Sinopec Shengli Oilfield Company,Dongying 257022,China;
2. Petroleum Exploration Administration Center,Sinopec Shengli Oilfield Company,Dongying 257001,China;
3. School of Geophysics and Information Technology,China University of Geosciences,Beijing 100083,China

弹性波高斯束逆时偏移首先通过弹性波高斯束叠加积分来构建格林函数,然后,基于格林函数进行波场延拓和互相关成像,是一种灵活且高效的深度域成像方法,具有面向目标成像的能力。针对高斯射线束宽度随传播距离增加快速发散的问题,在弹性波高斯束逆时偏移基础上,经过推导弹性波动态聚焦束算子,将地震波能量约束在有效范围内;随后引入基于相速度的各向异性射线追踪算法来校正各向异性对地震成像的影响。弹性波动态聚焦束逆时偏移不仅具有较高的计算效率,而且能够避免获取地下弱各向异性参数时的不确定性。VTI复杂构造模型和TTI断层模型测试结果表明,弹性波动态聚焦束算法能够将地震波束能量约束在有效范围内,从而提升中深层复杂构造的成像精度。

Elastic wave reverse time migration with Gaussian beams is a flexible and adaptable imaging tool for seismic data,and it can image subsurface structures more accurately.It adopts elastic wave dynamic Gaussian beams to characterize the Green function,then constructs forward and backward continuation wavefields,and finally calculates the imaging results through cross correlation.As the earth is essentially anisotropic,isotropic processing will result in artificial imaging.To solve the problem of rapid divergence of Gaussian beams with increasing propagation distance,this paper proposes a method based on the elastic wave reverse time migration with Gaussian beams.An operator of dynamic focused beams is derived for elastic waves to constrain seismic energy within the effective range.An anisotropic ray-tracing algorithm based on phase velocity is used to correct the influence of anisotropy on seismic imaging.This algorithm has high computational efficiency and can mitigate the uncertainties of obtaining weakly anisotropic parameters of subsurface media.The test results for a complex VTI structural model and a TTI fault model show that the proposed method can constrain seismic energy within the effective range to improve the imaging quality of deep complex structures.

山东省泰山产业创新领军人才专项资助项目(No.tscx202312059)、中石化科技攻关课题“胜利东部凹陷级地震深度域处理解释关键技术研究”(P23050)和“基于国产软硬件平台的成像技术系列移植与优化”(P24144)共同资助。

10.12431/issn.1000-1441.2025.64.01.006