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反射信号和高速干扰的振幅和波形随着炮检距的增大而变化。反射系数随入射角的变化而变化;薄反射层或厚过渡层的反射系数,透射效应及波的类型的转换也都随着入射角的变化而变化;点源的几何发散也是随着炮检距的变化而变化。反射地震记录的这些复杂性是人所共知的,但是,我们在设计标准模型时通常忽略了这些因素。由大角度所产生的明显影响可在处理时切除,对保留的数据也总是假设波形不变并具有双曲线型的正常时差,在CDP叠加之前常常应用道间平衡和自动增益控制来部分地补偿炮检距对反射的影响。本文的目的是想说明炮检距各种影响的重要性,并且说明分析这些影响的方法。射线参数与截距时间即(p-τ)曲线,以及反射,透射和波型转换系数与射线参数曲线都有助于识别某一特定层状模型中起重要作用的因素。p-τ曲线实际上是由一组易于解释的椭圆累加而构成的。p-τ曲线上的截距时间及斜率表示,x-t图上的一个波至出现的位置。p-τ曲线的曲率与x-t曲线的几何发散度有关。由于射线参数对于任一射线路径来说是固定的,因此也就容易识别出哪些是产生多次波和转换横波的主要射线参数和界面组合。对每个有意义的同相轴制作合成地震记录,就更有利于对资料的分析和解释。对具有较大速度差的地层模型中的高速噪音和具有较小速度差的第三系碎屑岩模型中的信号分析结果,说明了炮检距影响的重要性。
The amplitude and waveform of the reflected and high-speed disturbances vary with offset. The reflection coefficient changes with the angle of incidence; the reflection coefficient, the transmission effect and the type of wave transformation of the thin or thick transition layer also change with the incident angle; the geometric divergence of the point source is also with the gun inspection Distance changes and changes. It is well known that these complexities of reflection seismograms are common, but we often overlook these factors in the design of standard models. The significant effect due to large angles can be removed at the time of processing, the waveform remains invariant on the retained data and has a hyperbolic normal time difference, which is usually applied before the CDP overlay in part to Compensate for the effect of offset on reflections. The purpose of this article is to illustrate the importance of offset effects and to illustrate the ways in which these effects can be analyzed. The (p-τ) curve of the ray parameters and intercept time, as well as the reflection, transmission and mode conversion coefficients and the ray parameter curves all contribute to the identification of factors that play an important role in a particular layered model. The p-τ curve is actually composed of a set of easy-to-interpret ellipses. The intercept time and slope on the p-τ plot represent the position of a wave on the x-t plotted to the appearing position. The curvature of the p-τ curve is related to the geometric divergence of the x-t curve. Since the ray parameters are fixed for any ray path, it is also easy to identify what the primary ray parameters and interface combinations are for producing multiple and converted shear waves. Producing synthetic seismograms for each meaningful event is more conducive to data analysis and interpretation. The importance of offset effects is illustrated by the signal analysis of high-speed noise in a stratigraphic model with large velocity differences and Tertiary clastic models with less velocity differences.