基于共聚焦点道集的叠前深度偏移

共聚焦点(CFP)偏移技术是一种基于等时原理,将Kirchhoff积分法的一步偏移分两步聚焦（即激发聚焦和检波聚焦）来完成的叠前地震成像方法.该方法借助于逆时聚集算子和共聚焦点道集来实现叠前偏移成像.基于共聚焦点道集的叠前深度偏移是把基于共炮集的深度偏移的算法引入到CFP技术上来,基于波场延拓的理论来实现偏移成像,该方法首先生成共聚焦点道集,然后基于面炮合成的理论合成聚焦震源,最终通过相关成像来实现叠前偏移成像.该方法选取较少的聚焦点就可以实现对于地下构造的偏移成像,和炮域波动方程偏移相比,其计算效率得到了提高.通过模型试算和实际资料的试处理,验证了该方法在实现叠前深度偏移成像上的正确性和有效性.

Pre-stack depth migration using CFP gathers

The common-focus-point(CFP) migration technology is a kind of pre-stack seismic imaging methods based on the principle of equal traveltime,which separates Kirchhoff integral into two focusing steps (focusing on emission and focusing on detection). The method uses the time-reversed focusing operator and CFP gather to realize the pre-stack migration. We apply the recursive shot-record, depth migration algorithm to the CFP gathers of the seismic data and define this process as CFP-gather migration. We first get the CFP gathers and then use the theory of synthesis areal source to generate the focus source. Then based on the correlation migration we realize the pre-stack migration. Only choosing a few focusing points, we can get the migration result which is similar to the conventional common shot-records gather migration result, and improve the calculation efficiency. The experiment of the model and the process of the real data show the validity and the practicability of this method.