基于能量特征的微震信号初至拾取研究

Research on the First Break Picking of Microseismic Signals Based on Energy Characteristics

微震信号初至拾取是微震资料处理的基础,针对微震资料信噪比低,传统方法拾取精度差、无法适应噪声强度变化、复杂波形拾取困难等问题,提出了一种基于能量特征的微震信号初至拾取新方法。该方法首先对微震记录的信噪比进行估计,然后通过滑动时窗提取其提升小波包能量不纯度特征及改进的时窗能量比特征,根据构造的特征函数进行能量特征分析从而得到特征曲线,最后利用特征曲线的极值点拾取微震信号的初至到时。将该方法应用于仿真信号和实际微震资料,结果表明,该方法抗噪性好,不受噪声强度变化的影响,能够准确拾取最大峰值有延时的微震信号初至。

The first break picking of microseismic signals is significant for microseismic data processing.For the low signal-to-noise ratio(SNR)of microseismic data,the conventional methods offer poor performance in the accuracy of first break picking,adapting to the changes of noise intensity,and picking up complicated wave forms.This paper proposes a new method for the first-break picking of microseismic signals based on energy characteristics.Firstly,we estimate the SNR of microseismic records,and then extract the energy impurity characteristic of lifting wavelet packet and the improved energy ratio characteristic by sliding time window.The energy characteristics are analysed according to the constructed characteristic function to obtain the characteristic curve.Finally,the first-breaking time of the microseismic signals are picked up by the extreme points of the characteristic curve.The proposed method has been applied to stimulating signal and actual microseismic data,and the results show that this method has good anti noise performance,not affected by the change of noise intensity,and accurate to pick up the first break of the microseismic signal with the maximum peak delay.