基于共散射点道集的VSP速度分析

VSP velocity analysis based on common scattering point gather

针对现有VSP速度分析方法不能较好满足成像需要的现状,将地面地震中等效偏移距的概念引入到VSP中,提出了适合VSP的等效偏移距的定义公式,并相应的给出了VSP的共散射点道集的形成原理和步骤,以及通过这种道集进行速度分析的流程.通过模型资料和实际资料的试验表明,这种道集有更大的覆盖次数和更高的偏移距范围,其速度不受地层倾角的影响,可以适应斜井等其他的垂直观测系统.因而利用VSP的共散射点道集能和地面地震一样进行速度分析,为VSP等垂直接收的地震提供一种有效的速度分析手段,具有较好的应用前景.

As existing VSP velocity analysis method can not better adapt to the current situation of image needs, we introducing the equivalent offset from surface seismic for VSP,redefined the formula for the VSP equivalent offset,and gives the VSP common scattering point gathers formation principles and procedures and the flow for velocity analysis by which gathers.By analyzing the model data and field data show that this gather has greater folds and higher range of offset,the velocity is not affected by the formation dip,and can be adapted to other vertical survery.Therefore,the common scattering point gather can be used to velocity analysis same as surface seismic.this method has a good application prospects.