周期混叠对频域波形反演的影响分析及改进方法

周期混叠对频域波形反演的影响分析及改进方法 Analysis and Improvement of the Periodic Aliasing Influence on Frequency-Domain Full-Waveform Inversion 杨艳 YANG Yan 1 first-author 黄绍坚 HUANG Shaojian 1 张东 ZHANG Dong 1 秦前清 QIN Qianqing 2 胡英 HU Ying 3 徐凌 XU Ling 3 武汉大学物理科学与技术学院 武汉大学物理科学与技术学院 School of Physics and Technology,Wuhan University School of Physics and Technology,Wuhan University 武汉大学测绘遥感信息工程国家重点实验室 武汉大学测绘遥感信息工程国家重点实验室 State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,Wuhan University State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,Wuhan University 中国石油勘探开发研究院物探技术研究所 中国石油勘探开发研究院物探技术研究所 Department of Geophysical Technology,Research Institute of Petroleum Exploration and Development,PetroChina Department of Geophysical Technology,Research Institute of Petroleum Exploration and Development,PetroChina 分析了周期混叠的来源及其对频域正演波形记录精度的影响.在采样间隔固定时,快速傅里叶变换（FFT）变换不同的抽样点数N对正演波形记录精度有很大影响,提出了一种改善周期混叠的方法,通过合理地增大FFT变换的抽样点数使得单位冲激响应在N点处幅值更接近零,进而降低各个周期的混叠程度以提高频域波形正演和反演的精度.基于复杂模型Marmousi模型的正演和反演实验结果表明,该方法能较大幅度降低周期混叠程度,有效地提升正演和反演结果精度.在理论数据长度固定时,抽样点数过大反而会降低反演精度.本文以Marmousi模型原始观测系统以及数据长度为例,说明可以选取最佳的抽样点数来降低周期混叠对频域波形正演和反演的影响. The source of periodic aliasing and its influence on the accuracy of frequency-domain forward waveform record are analyzed. When sampling interval is fixed,different sampling point N of fast Fourier transform（ FFT） greatly affects the accuracy of the forward waveform record. This paper presents a method which increases the sampling point N reasonably to make the amplitude of unit impulse response after point N approaches zero value so that the degree of periodic aliasing is reduced. The performance of frequency-domain waveform forward and inversion is improved by the measure. The experimental results based on Marmousi model show that the method can depress the effect of periodic aliasing availably and increase the accuracy of the waveform forward and inversion. Meanwhile,the oversize number of sampling point brings down the accuracy of the waveform forward and inversion when the length of theoretical data is fixed. The calculation based on the original observation system and original data length of Marmousi model indicates that the optimal sampling point is selected to ensure the performance of waveform inversion. 周期混叠 频域 抽样点数 正演 反演 periodic aliasing frequency-domain sampling point numbers forward inversion 10.14188/j.1671-8836.2015.05.006 P631.4 国家科技重大专项课题（2011ZX05003-003）资助项目 2015-05-01 2021-03-31 5 61