多次回溯高精度快速射线追踪方法研究

Study on high-precision rapid ray tracing method by multi-retracing

(1.中国石油大学（华东）地球资源与信息学院,山东青岛266555；2.中国石油化工股份有限公司胜利油田分公司物探公司,山东东营257061)

College of Geo-resources and Information,China University of Petroleum (East China),Qingdao 266555,China

射线追踪的速度和精度直接影响地震资料的静校正和偏移成像的质量。针对复杂构造和不均匀介质中的地震波传播问题，提出了多次回溯高精度快速射线追踪方法。该方法基于费马原理，首先从震源出发选择目标点，以目标点为中心选定矩形计算网格，计算各网格点到目标点的旅行时，选择震源到网格点再到目标点的最小旅行时作为该目标点的传播时间，同时记录该点前一节点的坐标，这样介质中各目标点均有一条指向震源的射线路径；然后对射线进行回溯，对射线上的任意节点根据追踪半径确定回溯网格，计算地震波从震源到回溯网格中任意网格点再到目标点的传播时间，如果该时间比原目标点的传播时间短，则用该网格点替代原节点。根据精度要求选择合适的回溯次数更新节点信息，获得地震波传播的射线路径。模型试算结果表明，多次回溯高精度快速射线追踪方法是一种有效的初至波射线追踪方法。

The speed and precision of ray tracing affect the quality of statics and migration for seismic data.Aiming at the propagation problem of seismic wave in complex structures and inhomogeneous medium,a high precision fast ray tracing method by multi retracing was proposed.The method is based on Fermat principle,firstly,target point is chosen from source,a rectangular computation grid taking the target point as center is selected,the traveltime from every grid point to target point is calculated,selecting the minimum traveltime from source to grid point to target point as the propagation time for the target point,and recording the coordinate of a point before this target point until every target point in medium had one ray path pointed to source.Then,the ray path is retraced,for arbitrary node on the ray;the retracing grid is identified by ray tracing radius.The propagation time of seismic wave from source to arbitrary grid point in the retracing grid to target point is calculated,if the time is shorter than the original propagation time,then the original node is replaced by this grid point.Favorable retracing times are selected in terms of the precision acquirement to update the node information,and the ray path of seismic wave propagation is obtained.Model testing results that high-precision rapid tracing method by multi retracing is an effective first break ray tracing method.