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对实际野外记录在一台计算机上使用简单的射线追踪和使用流行的处理技术进行分析,产生共深度点的地震反射数据。用具有弯曲界面的恒速层来模拟复杂的地质形态。选择两个模型说明由弯曲的地质界面引起的问题,所谓弯曲界面即在深部以非线性方式横向变化的界面,它产生迭加速度明显而大的空间变化。使用具有深部构造且不带风化层的三层模型作为控制模型。为了进行比较,在靠近控制模型的表面放上一层厚度有变化的低速风化层。该低速层比普通薄风化层厚,所谓普通薄风化层系指现实可用的静校正技术能很好工作的风化层。对这两种模型都计算旅行时、时差、视均方根速度和层速度。风化层对均方根速度和旅行时引入误差,这里描述了补偿这些误差的方法。对旅行时应用的静校正会减小视均方根速度的起伏,而对厚风化层模型的数值却是“过校正”,以致使表层和深层的向斜(背斜)变成了错误的背斜(向斜)。可以作出这样的结论,对于分析共深度点地震数据处理的特殊问题,如在复盖层中大的横向变化所引起的推算速度的误差来说,采用计算机模拟是一种有用的工具。
The actual field records were analyzed using simple ray tracing on a single computer and using popular processing techniques to generate seismic reflection data at a common depth point. Constant velocity layers with curved interfaces are used to simulate complex geological formations. Two models were chosen to illustrate the problem caused by a curved geological interface, the interface that laterally varies in a deep, non-linear manner, resulting in significant and large spatial variations in stacking velocity. A three-layer model with a deep structure and without weathering layer is used as the control model. For comparison, a low velocity weathering layer of varying thickness was placed on the surface near the control model. The low speed layer is thicker than the normal thin weathering layer, which is a weathered layer that works well with virtually static correction techniques. Travel time, time difference, root mean square velocity and layer velocity are calculated for both models. Weathered layers introduce errors in rms velocity and travel, and methods to compensate for these errors are described here. Static correction of travel-time applications reduces the fluctuation of apparent root mean square velocity and “overcorrects” for thick-weathered layer models, causing surface and deep synclines (anticlines) to become erroneous Anticline It can be concluded that the use of computer simulation is a useful tool for analyzing the special problems of co-deep point seismic data processing, such as the errors in estimated velocity caused by large lateral variations in the overburden.