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, a new two-dimensional frequency-wavenumber domain common offset section prestack time migration algorithm is proposed. The proposed method generalizes the post-stack phase shift formula of zero offset section to a non-zero common offset section at constant speed. The formula is obtained by the numerical fitting method. The use of average velocity or stacking velocity allows the range of equations to be adapted to longitudinal velocity changes. Theoretically, the formula in this paper is accurate only at constant speed. However, the synthetic records and field data shows that this method can effectively image even if the velocity changes a lot, and more importantly, it can reduce the computational cost.