三维叠前深度偏移是解决复杂构造和速度横向变化剧烈地区地震资料成像问题的理想技术。应用三维叠前深度偏移成像技术,对CX气田的地震资料进行了三维叠前深度偏移处理,取得了良好的效果。其主要实现过程是:1在时间剖面上拾取速度层位,建立时间模型;2用相干反演法和叠加速度反演法相结合逐层求取层速度,建立层速度―深度地质模型;3用剩余速度分析修改和优化地质模型;4选用差分法实现三维叠前深度偏移。

3D prestack depth  migration is an ideal seismic data imaging technique for the area where there o ccur very complicated geologic structure and severe lateral velocity variation.3 D prestack depth migration imaging technique have been applied to CX gas field,a nd bring satisfactory effect.The main steps of 3D prestack depth migration can b e described in the following points:①Design time model by picking up velocity h orizons in time section;②Construct interval velocity-depth model by using the  interval velocities which have been obtained layer by layer with the use of cohe rent inversion and stacking velocity inversion methods;③Improve geologic model  through residual velocity analysis;④Achieve the 3D prestack depth migration after finite difference algorithm.