微地震震源矢量反演

为了提高微地震定位的精度,利用观测的三分量数据,从震源的矩张量分析开始,研究了微地震震源矢量反演方法。主要包括：①利用简化的高斯束射线追踪方法进行微地震震源矢量场的格林函数正演;②改进了走时距离反演,将常规网格搜索方法改进为黄金分割网格搜索方法;③在对数域进行走时正演和反演迭代计算,提高了径向距离对走时的敏感性。通过分析震源矢量、地层响应矢量及检波器响应矢量特性,结合检波器三分量坐标系标定不准确问题,研究并提出了震源矢量、检波器方位角同时反演的策略。在反演过程中加入了同一个震源事件绝对方位角相等的约束条件,提高了反演结果的可靠性。通过模型和实际资料分析,验证了上述方法的正确性和有效性。

In order to improve the accuracy of microseismic positioning,starting from the moment tensor analysis of source,microseismic source vector inversion method is studied for three-component data.The simplified Gaussian beam ray tracing method is used in wavefield forward modeling of Green function for microseismic source vector field.The conventional grid searching of traveltime inversion is replaced by golden section grid searching method.Traveltime forward modeling and inversion iteration calculation is carried out in logarithm domain to enhance the sensitivity of radial distance on traveltime.After analyzing the characteristics of source vector,formation response vector and receiver responses vector,combing with the analysis on inaccurate calibration problem of three-component coordinates for geophone,we proposed simultaneous inversion strategy for source vector and geophone azimuth.During the inversion,equal absolute azimuth of the same source event is added as the constraint condition to improve the reliability of the result.Theoretical and actual data proves the effectiveness and correctness of the method.