井间地震射线层析成像

Cross-Hole Seismic Tomography Using Ray Traveltime

本文采用射线走时对井间介质的地震波速进行层析成像，反演出井间介质的异常分布和构造．作者用快速弯曲射线迫踪法求解初值问题，用两步法和插值逼近法结合求解两点问题，避免了复杂运算，提高了运算效率和精度．反问题的数值计算用ＬＳＱＲ法．为了求取速度任意分布、对比度大的较为复杂介质模型的槽确初至时，本文采用动态程序法。该法灵活不受地质界面条件约束，且对介质速度分布未加任何限制。本文给出了几个算例．文中层析成像试验结果表明，此种层析成像算法是成功和有效的。

The tomographic image of seismic wave velocity of the media betweenthe crossholes by iterative ray traveltime mothed was studied in this paper.The authorsused the fast curved ray tracing method to solve the initial value problem,and used two step ray tracing method combining with the interpolation mothed to solve the two pointsproblem;avoided the complex calculation and improved the efficient and precision.The in verse problem was solved by LSQR method.In order to get the accurate first-arrival timesthrough the complex media with an arbitrary,discrete,discontinuous,large constrast ve locity distributions, we used the dynamic programminc traveltime computation method inthe paper.The method is flexible and not restricted by the geologic interfaces and the dos tribution of medium velocity.We presented some modeling results in the paper.The results showed that the algorithm is stable and applicable.