煤层水力压裂声发射监测信号特征分析

Characteristic analysis of acoustic emission monitoring signal in coal seam hydraulic fracturing

为促进声发射监测技术在煤层水力压裂效果评价中的应用，利用煤岩动力灾害声电监测仪对煤层水力压裂过程进行了实时监测，并采用傅里叶变换和小波包分析对采集的声发射信号特征进行了分析。现场试验结果表明：煤层水力压裂声发射监测有效信号主频在4701700Hz之间，低于井下噪声干扰信号主频；煤层水力压裂声发射监测有效信号能量分布主要集中在0～5000Hz频带，能量分布百分比为86．59／5～95．4％，且有效信号的能量分布主要集中在312．5～625，625～937．5，937．5～1250，1875～2187．5HZ等较低频带。

In order to promote application of acoustic emission monitoring technology in effect evaluation of coal seam hydraulic fracturing, coal seam hydraulic fracturing process was monitored by use of coal and rock dynamic disaster acoustoelectric monitor, and characteristics of acoustic emission signals collected in the process were analyzed through fourier transformation and wavelet packet analysis. The field test results show that main frequency of effective acoustic emission signals of coal seam hydraulic fracturing is in 470-1 700 Hz, which is lower than main frequency of underground noise interference signal. Energy distribution of the effective acoustic emission signals of coal seam hydraulic fracturing is concentrated in 0-5 000 Hz with proportion 86.5%-95.4%, and the energy distribution of effective signals is concentrated in low frequency band such as 312.5-625, 625-937.5, 937.5-1 250, 1 875-2 187.5 Hz.