基于希尔伯特-黄变换的低频探地雷达弱信号处理技术及其在天然气水合物勘探中的应用

摘要

低频探地雷达采集时间窗口大,深部信号受到地层衰减和频散的影响十分明显,真实反射信号往往伴随大量噪声,因此低频探地雷达信号可以视为典型的非稳态信号.引入对于非稳态信号处理效果非常好的HilbertHuang变换方法,在其基础上研究低频探地雷达深部微弱回波信号精细处理方法,能有效地滤除信号中的突变部分和噪声,从而实现对深层微弱信号的检测和提取.利用该方法对冻土带天然气水合物进行勘探,可以提取低频探地雷达信号在冻土底界及其下的天然气水合物储层的有效反射信号,取得了良好的效果.%As the low frequency ground penetrating radar acquisition time window is large,the influence of signal attenuation and dispersion on deep strata is very obvious,the real reflection signals are often accompanied by a lot of noise,and hence the low frequency GPR signal can be regarded as the typical non-stationary signal.The authors used the Hilbert-Huang transform method,which is very effective in non-steady signal processing,to study the weak signal processing method.This means can effectively filter the abrupt change part and noise in the signal,so as to detect and extract the deep weak signal.Using this method to explore the gas hydrate in permafrost zone,the authors successfully extracted the effective reflection signal of low frequency ground penetrating radar signals at the bottom of permafrost and its natural gas hydrate reservoir,thus obtaining good results.