低信噪比微地震事件初至拾取方法研究

针对低信噪比微地震事件的特点，研究了资料处理流程与初至拾取算法相结合的微地震事件初至自动拾取方法。通过处理方法优选和处理流程优化的反复测试，提出了适合低信噪比微地震事件初至自动拾取的最优处理流程。基于最优处理流程处理后的资料，从初至信息拾取的依据条件分析入手，首先求得每一道的微地震事件记录的振幅极大值，计算满足视速度变化时间范围内振幅最大值处初至点的振幅平均值;以该平均值设定门槛值，在给定的门槛值范围内计算滑动时窗内最大值的初至点;依次迭代计算，最终确定事件所有道的初至点。最后再对拾取的微地震有用事件初至曲线进行进一步的优化处理。不同地区实际资料的应用效果表明，所提出的低信噪比微地震资料最优处理流程和微地震事件初至自动拾取方法适应性强，结果可靠。

For the microseismic events with low S/N,the first arrival automatic picking method of microseismic events which combines data processing procedures and first arrival picking algorithm is studied.By continual tests,the optimum process procedures of first arrival auto-picking for low S/N microseismic events.Based on the microseismic data processed by optimum procedures,the first arrival picking and constraint conditions are analyzed;maximum amplitude of recorded microseismic events for each trace is calculated.In apparent velocity range constraints,average amplitude of first arrival points which meets maximum amplitude value is calculated,and the average amplitude value is set as the given threshold.At the given threshold value range,the first arrival points of maximum value in sliding window are calculated.After iterative calculation,all the first arrival for all traces are determined.Finally first arrival curves of picked useful microseismic events are optimally processed in further.The practical data in different area verify the effect of method.Not only is the adaptability strong,but the result is reliable.