共炮检距剖面相位移时间偏移

Phase-shift time migration of common-offset section.

本文提出了一种新的二维频率—波数域共炮检距剖面叠前时间偏移算法。本文方法在常速条件下将零炮检距剖面的叠后相位移公式推广到非零共炮检距剖面 ,该公式是用数值拟合方法得到的。运用平均速度或叠加速度可使公式的使用范围适应纵向速度变化。理论上本文的公式只在常速下是精确的 ,但合成记录和野外资料试算表明 ,即使速度变化较大 ,该方法也能有效成像 ,而且更重要的是还能减少计算量。

In this paper, we present a new 2 D common offset prestack time migration algorithm in frequency wavenumber domain. The method generalized the formula of poststack phase shift in zero offset sections to that of prestack time migration in non zero offset sections under the condition of constant velocity.The formulas are obtained by using numerical fitting method. This migration method can be suitable for vertically varying velocity by using an average velocity or stack velocity. Theoretically,these formulas are accurate only when velocity is constant.However,the synthetic and field data tests indicate that data with even reasonably rapid vertical velocity variation can be imaged effectively,and more important is also to significantly reduce the computational efforts.