地热井的天然源超低频电磁探测影响因素分析  

Analysis of factors affecting natural source SLF electromagnetic exploration at geothermal wells

作　　者：秦其明[1] 李百寿[1] 崔容菠[1] 蒋洪波[1] 王清培[1] 张泽勋[1] 张宁[1] 

机构地区：[1]北京大学遥感与地理信息系统研究所,北京100871

出　　处：《地球物理学报》2010年第3期685-694,共10页Chinese Journal of Geophysics

基　　金：国家科技重大专项课题(2008ZX05034-03);国家"863"计划(2007AA12Z163);北京市自然科学基金(4082013)项目资助

摘　　要：本文使用天然源超低频电磁探测仪对北京大学校园内两口地热井进行了超低频电磁探测试验,获得了1号地热井(京热119号井)连续五天、每天四个时刻的天然源超低频电磁探测数据以及2号地热井(京热168号井)单天的天然源超低频探测的数据.基于所获得的数据,开展了地热井的天然源超低频探测影响因素的研究,这些因素主要包括:天然源超低频电磁场和观测时间的关系、探头摆放方向与接收工频谐波干扰关系以及天气状况对观测数据质量的影响等.研究表明:(1)天然源超低频电磁探测信号存在明显的日夜交替变化,其中相对振幅-频率曲线在不同日期、同一邻近时刻总体的包络线具有较好的重复性和一定的稳定性;(2)工频谐波干扰场方向是影响因素之一,当仪器探头长轴方向与工频谐波干扰场的等效主轴方向平行时噪声影响最小;(3)雨天环境会对天然场源超低频信号中的高频部分造成较大影响.The Super Low Frequency （SLF） electromagnetic exploration was performed by using a nature source SLF electromagnetic detector at two geothermal wells in Peking University. The data of the SLF electromagnetic exploration at well JR-119 and JR-168 were obtained with the observation of continued five days and four times per day at well JR-119 and of one day at well JR- 168. Based on these data, the influencing factors of the SLF electromagnetic exploration were analyzed, which included the relationship between the nature source electromagnetic field and the time of observation, relationship between the sensor orientation and the received artificial electromagnetic interference, influence of weather conditions on the data quality and so on. The results showed that （1） There is an obvious day-night variation in the natural SLF signals, whereas the general envelopes of relative amplitude-frequency curves are repeatable and stable around the same time of different days; （2） The artificial electromagnetic interference field orientation is one of the influencing factors. When the long axis of sensor is parallel to the integrated axis of the artificial electromagnetic interference field, the noise is weakest. （3） Rain can exert great influence on the high frequency band of natural SLF signals.

关 键 词：超低频电磁探测 地热井 天然场源信号 影响因素分析 

分 类 号：P631[天文地球—地质矿产勘探]