Automatic NMO Correction and Full Common Depth Point NMO Velocity Field Estimation in Anisotropic Media

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• 作者：Mohamed Sedek ; Lutz Gross ; Stephen Tyson
• 关键词：NMO velocity ; Seismic anisotropy ; NMO correction ; Velocity variation with offset ; Velocity analysis
• 刊名：Pure and Applied Geophysics
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：174
• 期：1
• 页码：305-325
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geophysics/Geodesy;
• 出版者：Springer International Publishing
• ISSN：1420-9136
• 卷排序：174

文摘

We present a new computational method of automatic normal moveout (NMO) correction that not only accurately flattens and corrects the far offset data, but simultaneously provides NMO velocity (\(v_\mathrm{nmo}\)) for each individual seismic trace. The method is based on a predefined number of NMO velocity sweeps using linear vertical interpolation of different NMO velocities at each seismic trace. At each sweep, we measure the semblance between the zero offset trace (pilot trace) and the next seismic trace using a trace-by-trace rather than sample-by-sample based semblance measure; then after all the sweeps are done, the one with the maximum semblance value is chosen, which is assumed to be the most suitable NMO velocity trace that accurately flattens seismic reflection events. Other traces follow the same process, and a final velocity field is then extracted. Isotropic, anisotropic and lateral heterogenous synthetic geological models were built to test the method. A range of synthetic background noise, ranging from 10 to 30 %, was applied to the models. In addition, the method was tested on Hess’s VTI (vertical transverse isotropy) model. Furthermore, we tested our method on a real pre-stack seismic CDP gathered from a gas field in Alaska. The results from the presented examples show an excellent NMO correction and extracted a reasonably accurate NMO velocity field.