Stable Q Analysis on Vertical Seismic Profiling Data
Stable Q Analysis on Vertical Seismic Profiling Data
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DOI：
10.3997/2214-4609.20131840
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发表时间：
2013-10
期刊：
影响因子：
--
通讯作者：
Yanghua Wang
中科院分区：
文献类型：
--
作者：
Yanghua Wang
垂直地震剖面（VSP）提供了在地球地下不同深度传播的地震波形的直接观测。然而，基于不同深度的单个波形的Q分析存在不稳定性问题，通常是由于每个波形的频谱固有波动。为了提高稳定性，建议不要对单个波形进行Q分析，而要对综合观测进行考虑频率和时间的分析。时间-（或深度-）频域频谱转换为一维衰减测量相对于一个单一变量，频率和时间的乘积。虽然这种一维测量在时频域中比二维频谱具有更高的信噪比，但它也可以用来产生进一步稳定的补偿函数。然后通过对衰减测量值和数据驱动增益函数的最小二乘拟合实现两种稳定Q分析方法。这两种方法在理论上是一致的，在实际应用中具有较强的鲁棒性，可用于现场VSP数据的Q分析。
Vertical seismic profiling (VSP) provides a direct observation of seismic waveforms propagating to different depths within the Earth subsurface. Q analysis based on individual waveforms at various depths however suffers from a problem of instability commonly due to fluctuations inherent in the frequency spectrum of each waveform. To improve the stability, it is suggested that, instead of doing Q analysis on individual waveforms, conducting analysis on an integrated observation which considers both frequency and time. The time- (or depth-) frequency domain spectrum is transformed to a 1-D attenuation measurement with respect to a single variable, the product of frequency and time. While this 1-D measurement has higher signal-to-noise ratio than the 2-D spectrum in time-frequency domain, it can also be used to generate a further stabilized compensation function. Then two stable Q analysis methods are implemented by data fitting in least-squares sense to either the attenuation measurement or the data-driven gain function. These two methods are theoretically consistent and practically robust, for conducting Q analysis on field VSP data.