起伏地表低信噪比相干性约束高斯束偏移  

Coherence constraint Gaussian beam migration for low signal-to-noise ratio data in irregular topography

作　　者：王聪 栗学磊 岳玉波 郑江龙 陈明春 罗章清 WANG Cong;LI Xuelei;YUE Yubo;ZHENG Jianglong;CHEN Mingchun;LUO Zhangqing(Sinopec Geophysical Corporation Southern Branch,Chengdu 610213,China;Shenzhen Institute of Advanced Technology,Chinese Academy of Sciences,Shenzhen 518055,Guangdong,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China)

机构地区：[1]中石化石油工程地球物理有限公司南方分公司,成都610213 [2]中国科学院深圳先进技术研究院,广东深圳518055 [3]西南石油大学地球科学与技术学院,成都610500

出　　处：《世界地质》2025年第1期119-130,共12页World Geology

基　　金：福建省海洋物理与地质过程重点实验室开放基金课题(KLMPG-22-04);南方海洋科学与工程广东省实验室(珠海)项目(SML2021SP318);深圳市基础研究面上项目(JCYJ20210324102007021)。

摘　　要：本文以研究复杂山地低信噪比地震数据成像优化为目的,依据噪音与有效反射信号在相干性上存在的明显差异,创建了有效的相干性约束噪音压制方法,为山地成像实际应用提供理论与技术支持。针对起伏地表低信噪比地震数据面临的常规成像困难,提出起伏地表相干性约束高斯束偏移方法。利用高程时移修正消除了起伏导致的射线束分解不准确,并设计了束中心点与检波点的水平投影等效离散间隔方法,有效解决了起伏地表偏移存在的成像幅值不均衡弊端。在相干性约束方面,提出了新型稳定的复数域加权相干谱统计方法,并设计了有效反射信号的阈值提取和指数强化方法,实现了随机噪音与非相干性假成像的有效压制。利用2项合成数据与2项实测数据数值试验验证了该方法在噪音与假成像压制方面的有效性。起伏地表合成数据利用水平投影等效离散间隔方法实现了幅值均衡与划弧假成像压制;实测数据相干谱统计验证了加权相干谱比常规相干谱明显平滑稳定;层状模型合成数据利用相干谱阈值设置压制了大部分划弧假成像;实测山地数据证明了新提出的相干性约束方法对随机噪音的明显压制效果。新创建的相干性约束偏移成像方法在成像过程中有效压制了不具有相干性特征的噪音与假成像,明显提升了成像效果。To study imaging optimizing algorithms for low signal-noise rate(SNR)seismic data in irregular topography,an effective coherence constraint noise suppression method is established according to the obvious difference in coherence characteristics between noise and effective reflected signals,which can provide theoretical and technical support for practical applications of the imaging in irregular topography.In order to solve the problem of conventional imaging of low signal-to-noise ratio seismic data in irregular topography,a coherence constraint Gaussian beam migration method for irregular topography is proposed in this paper.The elevational correction of time-shift eliminates the inaccuracy of beam decomposition caused by irregular topography.Horizontal projection equivalent discrete interval(HPEDI)for beam center and receiver location is designed to solve the drawback of unbalance of imaging amplitude.About the coherence constraint,a new stable complex domain weighted coherence spectrum computing method is proposed,and the threshold extraction and exponential strengthening methods for effective reflection signal are designed to achieve the effective suppression of random noise and incoherent false imaging.Numerical experiments of 2 synthetic data examples and 2 measured data examples are applied to validate the effectiveness of the proposed methods in noise and false image suppression.The proposed HPEDI method can achieve significant image optimization in amplitude equalization and arc false image suppression for the synthesized data in irregular topography.The coherence spectrum of real measured data verifies that the weighted coherence spectrum is smoother and more stable than the conventional coherence spectrum.Most of the arc false images of the synthesized data in a layered model are suppressed by using the threshold of coherence spectrum.The irregular real measured low signal-to-noise ratio data prove that the proposed coherence constraint method suppresses random noise obviously.The proposed coherence co

关 键 词：低信噪比 相干谱 高斯束偏移 起伏地表 

分 类 号：P631.4[天文地球—地质矿产勘探]