背景速度替换与波场延拓速度场重建

在共中心点一半炮检距域中，利用波动方程的叠前双平方根算子，实现了炮点及检波点分层向下延拓。通过使用替换速度替换上覆地层速度，消除了背景速度对地层成像的影响，达到了提高深层地震资料处理质量的目的。利用叠前双平方根算子，将炮点和检波点波场向下延拓，并进行逐层剥离、速度场重建，消除了上覆地层对速度的影响，提高了速度分析的精度，为叠前偏移成像提供了可靠的速度信息。

Background velocity replacement and reconstruction of velocity field by wavefield continuation.

In common midpoint-half-offset domain, utilizing prestack double-square-root operator of wave equation to realize downward continuation for shot and receiver layer by layer,through using replacement velocity to replace overlaying strata velocity and eliminate the impact of background velocity on strata imaging, resulted in improving the processing quality of deep seismic data. Through downward continuation of wavefield at shot and receiver points by prestack double-square-root operator and stripping layer by layer,we can do precise velocity analysis to eliminate the influence of overlying strata on velocity and to reconstruct velocity field, so that the precision of velocity analysis can be improved, that provides a reliable velocity analysis means for prestack migration imaging.