地震数据处理中静校正对动校正速度的影响

由于传统静校正方法具有垂直时移的特征,经过静校正处理后各地震道的反射时间由浅至深产生了一个相同的时移。尽管各反射to时间在静校正处理后发生了变化。但在静校正过程中并没有改变反射波同相轴的形态,这就使得动校正速度(通常称之为叠加速度)发生了变化。动校正速度的变化量往住取决于静校正对反射1o时间的改变,而反射to时间的改变又往往与静校正基准面和地震数据处理基准面的选取有关。在表层结构相对简单地区,所求取的动校正速度与实际观测到的地震反射波视速度比较接近,但在表层结构复杂、地形起伏较大的地区.经过基准面静校正后,特别是经过区域静校正后,静校正对动校正速度的影响非常明显。在这种情况下,其动校正速度用于构造解释和地质解释会产生很大误差。通过理论模型的研究,定量分析了静校正对速度场的影响。为以后基准面的确定、基准面静校正的应用提供了理论依据。

Effect of Static Correction on Stack Velocity in Seismic Data Processing

The conventional static correction method is characterized by vertical time migration and following static correction processing the reflection time for all of seismic traces could give rise to the same time-migration responses from the shallow to deep strata. Such a variation at tO occurred in static correction that could not change the patterns of reflection events might allow the relevant dynamic correction velocity (normally called stack velocity) to be changed. This variation of stack velocity generally depends on variation of the static correction on reflected tO that tends to being related to selection of datum level available for static correction and base level for seismic data processing. In the relatively ordinary area of subsurface structure, it is closer between the derived stack velocity and observed apparent velocity of seismic reflection event; but in the complicated area of subsurface structure and relief region, there exist very obvious influences of the static correction velocity on the dynamic correction velocity following datum static correction and particularly regional static correction, hence, if the latter (stack velocity) is applied for structural and geologic interpretations, greater errors will take place in this case. This paper makes a quantitative analysis of the influence of static correction on seismic velocity field based on above results from theoretical model study, and provides sound theoretical bases for the datum determination and application of the datum static correction in future.