DMO和叠前时间偏移的共同起点

The same start of DMO and prestack time migration.

王华忠 ,徐蔚亚 ,徐兆涛 ,匡斌 ,马在田 .DMO和叠前时间偏移的共同起点 .石油地球物理勘探 ,2 0 0 2 ,37(3) :2 2 4～ 2 2 9DMO和叠前时间偏移对于改善速度分析及叠加效果 ,最终提高剖面成像质量都是很有用的工具 ,一般在共偏移距道集中进行。其实现方法有多种 ,如等价偏移距方法 (equivalent offset migration,Bancroft et al,1994 )、DMO+PSI(prestack imaging)方法 (Gardner,1986 )和非成像的炮集偏移 (non- imaging shot- record m i-gration,Berryhill,1996 )等。这些方法的一个共同特点是用一个新定义的偏移距替代原来的偏移距。在每一种方法中 ,成像过程都归结为以新偏移距定义的共反射点双曲线型时—距关系上的动校正。本文中 ,我们证明了不同方法的 DMO和叠前时间偏移有其共同起点——双平方根算子 ,说明它们在原理上是等价的 ;最后我们提出了基于波动方程的 DMO和叠前时间偏移方法。

DMO and prestack time migration are useful both for imaging and for velocity analysis. Several alternatives to common offset processing have been introduced recently: John Baccroft's (1994) 'equivalent offset migartion', Gerry Gardner's (1986) 'DMO plus prestack imaging', and John Berryhill's (1996) 'non imaging shot record migration'. Each of these methods replaces the usual offset coordinate with a pseudo offset variable that combines offset and midpoint. In each approach, an imaging step is followed by hyperbolic moveout over the new pseudo offset. In this paper, we prove that DMO and prestack time migration come from the same starting point which is the double square root equation and propose wave equation based DMO and prestack time migration.