地面与井中联合观测的微地震定位和速度结构同时反演

为解决速度模型估计不准带来的微地震定位误差，本文推导了旅行时关于层速度、层界面深度及震源参数的偏导数，利用最短路径算法计算射线路径和旅行时，结合共轭梯度法求解带约束的阻尼最小二乘问题，发展了一种利用微地震初至旅行时数据同时进行速度结构反演和微地震定位的方法。数值模拟实验表明，该算法能够有效反演地下介质的速度结构（层速度和层界面深度）并进行微地震定位，且方法对随机噪声不敏感。

A method for locating microseismic source and inverting velocity structures with surface and borehole arrival times

In order to solve the problem of source-locating error caused by inaccuracy of velocity model, we propose a method to locate microseismic source and simultaneously invert velocity structures with arrival times recorded at surface and borehole receivers.The traveltime derivatives with respect to velocity, layer interface depth, and microseismic event parameters are derived, and the ray paths and arrival times are calculated with the shortest path algorithm.In combination with the conjugate gradient approach, damping minimum norm and constrained least square problem are solved.Numerical test results show that the inversion algorithm can not only recover velocity structure (interval velocity and interface depth) but also locate source positions, and it is not sensitive to random noise.