山前带逆掩构造保幅FFD叠前深度偏移  

Applications of amplitude-preserved FFD prestack depth migration for complex overthrust structures in piedmont zone

作　　者：吕彬[1] 王西文[1] 王宇超[1] 苏勤[1] 杨飚 林明强 

机构地区：[1]中国石油勘探开发研究院西北分院,甘肃兰州730020 [2]中国石油吐哈油田公司,新疆哈密839009

出　　处：《石油地球物理勘探》2011年第5期720-724,836+662,共5页Oil Geophysical Prospecting

基　　金：国家科技重大专项(2011ZX05007-006)资助

摘　　要：山前带逆掩构造区上覆高速地层对地震波传播能量具有比较严重的屏蔽作用,因而导致逆掩下伏构造成像比较困难。如今广泛采用的Kirchhoff积分法叠前深度偏移由于其自身算法的限制难以对其精确成像。基于此,本文引入了保幅FFD(傅里叶有限差分)叠前深度偏移方法,通过在传统延拓算子的基础上增加振幅恢复项求得保幅延拓算子,并给出保幅偏移的成像条件,从而实现了保幅FFD叠前深度偏移。数值试验及实际资料处理结果均表明:该方法能够有效补偿地震波场传播中的能量损失,提高逆掩下伏构造的成像质量。Overlying layers with high velocity have serious shielding effect for seismic energy propagation in complex overthrust structures of piedmont zones.So it is difficult to image underneath overthrust structures.And at present widely used Kirchhoff integration pre-stack depth migration could not obtain precise imaging because of its own limitation.In this paper,we propose an amplitude-preserved FFD(Fourier finite difference) pre-stack depth migration method.By adding amplitude recovery items to conventional extrapolation operators,the amplitude-preserved extrapolation operators could be obtained.And we also give out imaging conditions for amplitude-preserved migration.So the amplitude-preserved FFD pre-stack depth migration could be realized.Numerical test results of model dataset and real seismic dataset show that the method could effectively compensate energy loss of seismic propagation.The imaging of overthrust underneath structures could be improved by applying this method.

关 键 词：山前带 逆掩构造 单程波方程 保幅偏移 FFD 

分 类 号：P631[天文地球—地质矿产勘探]