低信噪比地震数据折射初至的判定与识别
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摘要
静校正是起伏地表条件下地震资料处理的关键技术,其精度依赖于初至拾取的准确性,但低信噪比往往导致初至难以被准确地判别与拾取。折射波干涉法可以提高初至折射波的信噪比,本文在原干涉法的基础上做了三点改进:通过引入反向互相关函数解决近道地震记录叠加次数低的问题;分析干涉法产生"假事件"的原因,并针对互相关扭曲波形产生的"假事件",应用子波整形对其进行压制;在处理实际三维地震资料时,由于可用于干涉法的炮检点组合数较少导致叠加次数较少,引入检波点域干涉法,增加所有道的叠加次数。合成地震记录和实际地震资料处理结果均验证了本文方法的适用性。
Static corrections play a key role to process low SNR data on undulating surface.Their effectiveness relies on the accuracy of first-arrival times.However,it is difficult to recognize and identify first arrivals on low SNR data.Interferometry is able to improve SNR of first-arrival refraction.Three improvements are made for traditional interferometry. First inverse correlation function is introduced to make up the lack of stacking fold in near-offset traces.Then multiple reasons of spurious events generated by interferometry are analyzed and the wavelet shaping method is implemented to suppress spurious events caused by wavelet distortion.Finally interferometry in common receiver gathers is developed to increase the stacking fold,especially when there are few available source-receiver combinations for 3D exploration field data.The improved method is tested on synthetic data and real data and good results are achieved.
引文
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