基于三阶累积量一维切片的微地震信号时延估计

由于微地震有效信号易受环境噪声的干扰,严重影响时延估计值获取的准确性.基于此,提出了基于三阶累积量一维切片的方法进行微地震信号时延估计.首先计算信号的三阶自累积量和互累积量,为减少运算量满足野外实时要求取其一维切片,最终通过准则函数求取时延值.相对于传统的互相关方法,该方法对相关性未知的高斯噪声具有不敏感的特点,对相关高斯噪声有更强的抑制能力.仿真结果表明,在添加信噪比为-5~15dB的随机高斯噪声和相关高斯噪声时,其时延检测概率和均方根误差优于互相关方法.在实际资料应用中,对实际微地震噪声进行了概率分布统计分析,并且基于井地联合监测方式,选取井中信号作为参考道对地面资料进行时延值的求取.仿真和实际资料处理验证了该方法的有效性和实用性.

Time Delay Estimation of Microseismic Signal Based on One dimensional Slice of Three order Cumulants

The effective microseismic signals are disturbed by noises, so the precision of time delay estimation is affected. Because time delay estimation is the key to determine location accuracy, one dimensional slice method based on third order cumulants was proposed for microseismic signal time delay estimation. Firstly, the three order self accumulation and mutual accumulation of the signals were calculated, then, one dimensional slice was obtained in order to reduce the computation and to satisfy the field real time requirements. Finally, the time delay value was obtained by the criterion function. Compared with the traditional cross correlation method, this method has less sensitivity to the Gauss noise with unknown correlation and has stronger inhibition ability to the correlated Gauss noise. The simulation results show that the detection probability and root mean square error are better than the traditional method under the influence of Gauss random noise and correlated noise with SNR=-5 dB to SNR=15 dB. In the implementation of real data, the real microseismic noise probability statistic characteristics were analyzed and the data in the well were selected as references, and then the time delay value to the ground data was calculated on the basis of the surface and borehole observation. The validity and the practicability of this method were verified.