模型正演技术在叠前深度偏移中的应用

川西龙门山前缘构造非常复杂,逆掩推覆构造带构造形变强烈,构造幅度大,地层倾角陡,断块发育,地震波场复杂,速度横向变化大,常规叠后时间偏移处理成像效果较差.利用已有地震资料解释成果,建立地质模型进行射线追踪正演模拟分析,从而指导叠前深度偏移初始速度模型的建立,达到了复杂地表下复杂构造精确成像的目的.事实证明,这种将模型正演应用于叠前深度偏移处理成像的方法对于提高地震资料处理的成像质量具有非常重要的作用.

Application of forward modeling in pre-stack depth migration

The frontal structure of Longmenshan in the west of Sichuan is very complex,showing intense structure deformation in overthrust belt,high structure amplitude,steep stratigraphic dip,developed fault blocks,complex seismic wave field,frequent change of lateral velocity,and poor image of post-stack time migration processing.Geological model is set up by using seismic data interpretation result to perform ray-trace forward modeling analysis,and to guide the establishment of initial velocity model of pre-stack depth migration,thus reaching the purpose of precise image of complex structure under complex surface.It has been proved that application of forward model to pre-stack depth migration image is very helpful to improving image quality of seismic data processing.