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地震资料处理中主要努力的目标之一,是对多道资料采集方式带来的几何效应即正常时差进行校正。一般说来,它涉及到拾取相干的反射信号,确定这类信号的时间(t)与时差(△t)之间的关系,确定各个接收道的校正时间,以及将选择的道集合为迭加剖面。这些运算的大部分都是自动的。对于自动拾取的反射波来说,可以采用好几种速度分析方法,而且各个道的校正和集合程序也是很普通的。然而,测定能在有用的反射波、多次反射波和噪音之间作出判断的正常时差,多数仍然还是手工计算。现在我们描述一种能自动测定这种时差或者t-△t函数的机器方法。这个方法广泛利用观察到的现象:t-△t函数能被绘在对数座标的时差(△t)与线性座标的时间(t)的关系图上的线段曲线很好地近似。讨论了确定这些直线函数的准则,其中包括对线段斜率的限制。举出了几个应用实例。在这些例子中,用机器导出的时差函数校正的地震剖面,同用一般方法计算的时差函数校正的地震剖面作了对比。
One of the main goals of seismic data processing is to correct the geometric effects caused by multi-channel data acquisition, ie normal time difference. In general, it involves picking up coherent reflected signals, determining the relationship between the time (t) and the time difference (Δt) for such signals, determining the correction time for each receive channel, and combining the selected channels into a superposed profile. Most of these operations are automatic. There are several speed analysis methods that can be used to pick up reflected waves automatically, and correction and assembly routines for each lane are also commonplace. However, determining the normal time difference that can be used to make judgments between useful reflections, multiple reflections, and noise remains mostly manual. We now describe a machine method that automatically measures this time difference or t-Δt function. This approach makes extensive use of the observed phenomena: the t-Δt function can be approximated well by the line curve plotted on the plot of the time difference (Δt) versus linear coordinate time (t) for logarithmic coordinates. The guidelines for determining these line functions are discussed, including the limit on the slope of the line. Cite several examples of applications. In these examples, the seismic profiles corrected by machine-derived time difference functions are compared with the seismic profiles corrected by the time-difference function calculated using the general method.