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在层状介质中,当地震波非垂直入射时,其反射响应取决于地层的弹性常数和厚度。除 AVO 之外,我们还可以利用相位、频率与炮检距的关系来增加地震数据的特征值。基于对地震道的分析描述,我们能通过计算其振幅、相位和频率指标来进行综合的振幅、相位和频率与炮检距关系(APF.VO)分析。这已被理论和实际资料所证实。理论记录分析表明:通过改变给定目的层的孔隙流体或岩性条件来修改其速度和厚度,得到一套 APF.VO 变化的结果图。特别是,与反射中的干涉和临界角现象有关的影响,能够通过以相位移和振幅变化为指示的相位和振幅与炮检距关系(P.A.VO)清楚地检测出来。而频率指标主要受传播子波谱的控制。基本理论模型是由已知井的资料得到的。通过对井旁测线上的一些 CDP 道集进行分析,可以看出实际数据中与干涉和临界角有关的特征,在 APF.VO 图上同样表现出来了。它们的振幅指示相当稳定,而相位指示空间变化大,对噪声比较敏感。在实际层状结构中,常存在与炮检距有关的局部干涉,并使得地震数据严重畸变。因此在AVO 解释及反演过程中必须解决这一问题。在反演技术中,相位的频率与炮检距的变化关系有助于传统的 AVO 解释,并提供了用于反演技术的更丰富的资料。
In layered media, when the seismic waves are not perpendicularly incident, the reflection response depends on the elastic constants and thickness of the formation. In addition to AVO, we can also use the relationship between phase, frequency and offset to increase the eigenvalues of seismic data. Based on the analysis of seismic traces, we can perform a comprehensive analysis of amplitude, phase and frequency versus offset (APF.VO) by calculating their amplitude, phase, and frequency indices. This has been confirmed by both theoretical and practical information. Theoretical analysis shows that the velocity and thickness of APF.VO can be obtained by changing the pore fluid or lithology conditions of a given target. In particular, the effects associated with interference and critical angle phenomena in reflection can be clearly detected by the phase-to-offset relationship (P.A.VO) with the phase and amplitude indicated by the phase shift and amplitude variations. The frequency index is mainly controlled by the propagation sub-spectrum. The basic theoretical model is derived from the well data. By analyzing some CDP gathers on the sideline, we can see that the characteristics related to the interference and the critical angle in the actual data are also shown on the APF.VO diagram. Their amplitude indication is quite stable, while the phase indication of space changes, more sensitive to noise. In the actual layered structure, there often exist local interferences related to the offset and seriously deform the seismic data. Therefore, this problem must be solved in the process of AVO interpretation and inversion. In inversion techniques, the relationship between the phase frequency and the offset varies with traditional AVO interpretation and provides a wealth of information for inversion techniques.