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叠后地震数据,是共反射点道集叠加的结果,虽然提高了信噪比,但是也损失了丰富的叠前地震道集信息,建立在叠后数据基础上的叠后波阻抗反演不可避免的掩盖了很多AVO类信息.实际地震数据的采集都是非零炮检距的炮集记录,这种叠前地震数据提供了多种波型地震信息,对流体和岩性更加敏感.因此,利用叠前道集或者部分道集信息的叠前地震反演能够大大提高预测的精度,扩展弹性阻抗技术不仅使用了丰富的叠前地震道集信息,同时还解决了常规弹性阻抗技术不稳定和实用性的问题,使叠前反演更具有实际应用价值.通过弹性阻抗公式和扩展弹性阻抗公式的对比分析,验证了扩展弹性阻抗反演更加稳定.在利用扩展弹性阻抗技术进行反演前先对扩展弹性阻抗公式进行对数变换,建立梯度阻抗和声波阻抗的坐标系统,通过计算最佳旋转角度下的弹性阻抗,进行岩性预测.同时指出了计算声阻抗和梯度阻抗的方法,并分析了岩性预测基本原理.应用扩展弹性阻抗技术在我国西部某气田河道砂体识别中取得较好的效果.
Post-stack seismic data are the result of the superposition of common reflection point gathers. Although the signal-to-noise ratio is improved, abundant prestack seismic gathers information is also lost. Post-stack wave impedance inversion based on post-stack data is not possible Avoid masking a lot of AVO class information.All the actual seismic data acquisition are non-zero offset shot record, this prestack seismic data provides a variety of waveforms of seismic information, more fluid and lithology.Therefore, The prestack seismic inversion using prestack gathers or partial gathers information can greatly improve the prediction accuracy. The extended elastic impedance technology not only uses abundant information of prestack seismic trace gather, but also solves the problems of conventional elastic impedance technology instability and Practicality, the prestack inversion has more practical value.Through the comparative analysis of the elastic impedance formula and the extended elastic impedance formula, it is verified that the extended elastic impedance inversion is more stable. Before using the extended elastic impedance technique to perform inversion The logarithmic transformation of the extended elastic impedance formula is used to establish the coordinate system of gradient impedance and acoustic impedance. By calculating the elastic impedance under the optimal rotation angle, At the same time he pointed out that the method of calculating the acoustic impedance and the impedance of the gradient, and the basic principle of lithology prediction. Application extended elastic impedance technology to achieve better results in the recognition of a channel sand gas field in western China.