摘要
品质因子Q是定量描述黏弹性衰减的重要参数,准确估计Q值有利于储层识别、烃类检测,还可用于反Q滤波来提高地震资料的分辨率。传统的Q值估计方法包括对数谱比法、中心频率偏移法和峰值频率偏移法等,其中对数谱比法的抗噪性较差,而中心频率偏移法和峰值频率偏移法则存在依赖地震子波类型的问题。针对这些问题,提出一种基于S变换和变分法提取品质因子Q的方法。首先,通过研究非平稳褶积模型,推导出非平稳地震数据在S变换域的近似表示形式;其次,在近似表示的基础上,建立了关于品质因子Q和地震子波的目标函数,并基于变分法最小化目标函数,得到Q值估计表达式;最后,为了提高该方法的准确性与抗噪性,设计了一种自适应积分区间选择的方案,该方案可根据地震数据的时频谱自动计算积分区域的频率参数。模型算例测试结果表明,所提出的Q值估计方法不依赖于地震子波的类型和窗函数的长度,同时对噪声具有较好的鲁棒性。实际数据计算结果进一步验证了该方法在Q值估计中的有效性。
Quality factor Qis an important parameter to quantitatively describe the viscoelastic attenuation.Accurate Qestimation is beneficial to reservoir identification and hydrocarbon detection.It can also be used for inverse Qfiltering to improve the resolution of seismic data.The traditional Qestimation methods include logarithmic spectrum ratio(LSR),center frequency shift(CFS),and peak frequency shift(PFS),etc.LSR has poor noise immunity.Both CFS and PFS depend on the type of seismic wavelet.In response to these problems,this paper proposes a robust Qestimation method based on the S transform and variational method.Firstly,by studying the nonstationary convolution model,we derived the approximate representation of nonstationary seismic data in the S domain.Secondly,on the basis of approximate representation,the objective function of quality factor Qand seismic wavelet is established and minimized based on the variational method,thereby obtaining the expression of Qestimation.Finally,we designed an adaptive selection scheme of an integral interval to improve the accuracy and noise resistance of the method.This scheme can automatically calculate the frequency parameters of the integration area based on the time-frequency spectrum of seismic data.Model examples demonstrate that the proposed method does not rely on the wavelet type and the length of the window function and shows good robustness to noise.The real data further verifies the effectiveness of the method in Qestimation.
作者
许李囡
高静怀
杨阳
高照奇
王前
XU Li'nan;GAO Jinghuai;YANG Yang;GAO Zhaoqi;WANG Qian(School of Information and Communications Engineering,Xi'an Jiaotong University,Xi'an,Shaanxi 710049,China;School of Mathematics and Statistics,Hubei University of Arts and Science,Xiangyang,Hubei 441053,China)
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2022年第1期82-90,I0004,共10页
Oil Geophysical Prospecting
基金
科技部国家重点研发计划“非常规油气三维地震成像的数学方法与超分辨反演高效算法”(2020YFA0713400)资助。
关键词
地震波衰减
S变换
变分法
自适应参数选择
Q值估计
seismic wave attenuation
S transform
variational method
adaptive parameter selection
Qestimation
