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本文提出了一种推断近地表构造的首波旅行时间反演的新方法.沿折射线相遇段所计算的旅行时间被用来重建地下第一个折射层的形状以及得出沿该界面的折射速度变化.所得信息可作为进一步处理的基础,比如说,用来进行近地表的静校正的计算.该方法优点之一在于确定折射界面的形状与确定折射界面速度互不相关,该方法可绘制多次覆盖时折射界面的几何形状或速度的急剧横向变化图.本文还给出了该反演技术的两个实例.其一利用了合成数据集;另一个利用了在沉积充填的深地堑上方爆破而得到的野外资料.利用合成数据集得到的结果对该方法予以证实并验证了误差分析的结论,其中,利用炮点左侧和右边接收记录来确定的折射界面速度误差符号相反,因此,真正的折射速度应位于这两个估值之间.一组野外数据反演得到的折射图象与常速反射迭加非常吻合,并说明了射线反演方法可处理折射速度或折射界面形状的剧烈的横向变化.
In this paper, we propose a new method to deduce the traveltime of the first wave of the near-surface structure, and the travel time calculated along the line of the ray is used to reconstruct the shape of the first refraction layer in the subsurface and to obtain the refraction The resulting information can be used as a basis for further processing, for example, for near-surface static correction calculations.One of the advantages of this approach is that it is not relevant to determine the shape of the refractive interface and to determine the refractive interface velocity, In the case of multiple overlays, the geometry of the refraction interface or the sharp lateral variation of the velocity is shown in Fig. 1. Two examples of this inversion technique are also given in this paper, one of which utilizes a synthetic dataset and the other uses a deep graben The results of the synthetic data set are used to confirm this method and verify the conclusion of the error analysis. The sign of the velocity error of the refraction interface determined by using the receiving records to the left and the right of the shot has the opposite sign. Therefore, , The true refraction speed should lie between these two estimates. The refraction images retrieved from a set of field data are in good agreement with the normal velocity reflections and It shows that the ray inversion method can handle the sharp lateral changes of the refraction speed or the shape of the refraction interface.