基于薄层模型的有限频率井间地震波层析成像

地震射线层析成像需要进行旅行时和射线路径的计算，而复杂介质的地震射线追踪方法受到地震波频率有限的影响。为此，提出了基于薄层模型的有限频率井间地震波层析成像方法。给出了方法的基本原理，即在Fresnel带内寻找长度最短的路径，在弯曲射线追踪方法表示旅行时大小的目标函数中，加入一项与射线长度有关的惩罚项，把有限频率地震射线追踪问题转化为求解该目标函数无约束最优化问题，从而实现基于薄层介质模型的有限频率地震射线追踪，最后通过反演计算实现井间地震射线层析成像。该方法计算简单，易于实现，理论模型试算验证了方法的有效性。

A finite frequency seismic crosshole tomography based on thin layered model

Seismic crosshole tomography is a key method for getting velocity profile of crosshole. Algebra reconstructs is widely used in seismic crosshole tomography,including ART and SIRT, but the travel time and path must be computed on tomography by ray tracing.In order to obtain the shortest path within Fresnel zone,based on the Bube's (2001) idea. we are constructed an unconstrained optimization function. add to penalty item involved ray length, that is related to the traveltimes of the path and realized ray tracing of finite frequency seismic wave, on thin bed layer model and realized the finite frequency seismic crosshole tomography. The algorithm is verified on theoretical model