当前的三维VSP地震数据偏移成像实现都是在共炮点道集或共检波点道集中逐个道集循环进行的,计算效率相对较低.根据三维VSP观测系统中炮点和检波点布置的特殊性和地震波场满足线性叠加的特性,本文提出了一种三维VSP数据的高效偏移成像方法,即首先通过对三维VSP共接收点道集进行地震数据的广义合成得到一种超道集,然后在共接收点道集的波场深度外推过程中逐步应用多震源波场对超道集进行偏移成像,即利用一次波场深度外推循环完成对所有共检波点道集数据的偏移成像.通过三维VSP模型数据与实际地震数据的偏移成像试验验证了这种高效的超道集偏移成像方法可取得与常规共检波点道集相当的偏移成像效果,还具有极高的计算效率,其计算量与单个共检波点道集的偏移成像计算量相当.%At present the migration of 3D VSP seismic data is implemented through the gathers one by one in common-shot-gather domain or common-receiver-gather domain, so its calculation efficiency is relatively low. Based on the special property of the shots and receivers configuration in 3D VSP survey geometry and the characteristic of linear stacking of seismic wavefield, in this paper a highly efficient migration method for 3D VSP data is proposed. It first generates one kind of super-gather by using the generalized synthesis of seismic data to the 3D VSP common-receiver gathers, and migrates the super-gather by recursively using multi-source wavefield in the depth extrapolation of common-receiver gathers, which uses one recursive depth extrapolation to implement the migration of all the common-receiver gathers. The migration tests of theoretical 3D VSP data and real 3D VSP data demonstrate that the high-efficiency super-gather migration method can get the same migration results as that of the conventional common-receiver gathers migration, and can have very high calculation efficiency, its computational amount is almost equal to that of one common-receiver gather migration.
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