青藏高原冻土区AMT探测天然气水合物采集试验  

AMT acquisition experimental study of gas hydrate exploration in the permafrost region of the Tibetan Plateau

作　　者：裴发根[1,2,3] 何梅兴 仇根根[1,2,3] 杜炳锐 白大为[1,2,3] 

机构地区：[1]国土资源部地球物理电磁法探测技术重点实验室,河北廊坊065000 [2]国家现代地质勘查技术研究中心,河北廊坊065000 [3]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000

出　　处：《物探与化探》2017年第6期1113-1120,共8页Geophysical and Geochemical Exploration

基　　金：国家高技术发展计划("863计划")课题(2012AA061403);国家127专项项目(GZHL20110324;GZH201400305);中国地质调查局地质调查项目(DD20160224)

摘　　要：音频大地电磁测深(AMT)在"死频带"(500~5 000 Hz)内,容易引起视电阻率与相位曲线畸变。为获得探测天然气水合物的高质量AMT数据,在青藏高原冻土区开展了AMT采集试验研究,涉及到5个采集参数,分别为采集时段、采集时长、天气、电极距与测点密度。通过参数对比试验发现:为获取高质量的AMT数据,采集时段应选择在下午至晚上区间,采集时长≥40 min,选用较小的电极距(50~100 m),选择多云或阴天进行采集,此外,采用密度较高的点距布设(点距100 m或更小)有利于构建准确的电性模型。Obtaining high-quality original data is a key step. Especially in the ＂dead band＂ （500 - 5000 Hz）, the signal of the AMT field source which is the natural electromagnetic field is weak and the apparent resistivity and phase curve are distorted in the dead band. To obtain high-quality data in the permafrost region of the Tibetan Plateau, the authors carried out AMT acquisition experiments of the natural gas hydrate exploration. These experiments included five acquisition parameters, i.e., the acquisition range of time, the acquisition time length, the weather, the electrode length and the density of measuring points. The experiments show that, for the pur- pose of obtaining high-quality AMT data, the acquisition time range should be selected from the afternoon to the evening, the acquisi- tion time length should be more than 40 minutes, a smaller electrode length （eg. 50- 100 m） should be chosen, and the cloudy days are favorable. In addition, the use of high density of measuring points is helpful to building an accurate electrical model.

关 键 词：天然电磁场 音频大地电磁测深 冻土区 死频带 反演 

分 类 号：P631[天文地球—地质矿产勘探]