零偏移距VSP测量仅能提供以井为中心的菲涅尔带内的地下信息.偏移震源位置使反射点向偏离井的方向移动,从而提供横向的复盖信息。这种数据的常规处理导致地下映象的畸变。利用简单的射线追踪方法,可将地下映象重建到人们所熟悉的地面地震剖面的坐标系统下。这种简单的数据成像技术是以假设地层是水平的为基础,并需要一个垂直速度剖面。偏离井口放置震源的技术首先用于单偏移距震源的VSP测量。然而,来自于任何一种测量几何图形(例如井口震源的斜井VSP,多偏移距VSP等)的测量数据均可以被映象到与之相适合的地面地震剖面昕定义的坐标系统中。为了使这种测量得到最好的结果,必须确定目的区域,并用简单的模型技术优化震源的位置。任何一种VSP的测量数据都是可实现的实验结果,其本身遵循波动方程。这意味着可以利用波动方程偏移将这些数据偏移到它的真正位置。尽管实际工作中存在着许多困难,从理论上讲,波动方程偏移较之射线追踪技术更为可靠。 Zero-Offset VSP measurements can only provide information about the subsurface within the well-centered Fresnel zone The offset source position moves the reflection point away from the well, providing lateral overlay information. The conventional handling of such data leads to distortion of the underground image. Using simple ray tracing methods, the underground image can be reconstructed to the familiar coordinate system of the surface seismic section. This simple data imaging technique is based on the assumption that the formation is horizontal and requires a vertical velocity profile. The technique of placing a source off-axis was first applied to VSP measurements at a single-offset source. However, the measurement data from any of the measuring geometries (eg, wellhead VSP, multi-offset VSP, etc.) can be mapped into the coordinate system defined by the appropriate surface seismic section. In order to get the best results from this measurement, it is necessary to determine the area of ​​interest and optimize the location of the source with a simple model technique. Measured data for any of the VSPs is a realistic experiment and follows the wave equation. This means that the data can be shifted to its true position using the wave equation offset. Although there are many difficulties in practical work, theoretically speaking, the wave equation migration is more reliable than the ray tracing technique.