Abstract: The source of passive ultra-lowfrequency(ULF), the elimination of noise, and the interaction of ULF with underground substances are discused andtested. The zero magnetic field experiment shows that the ULFreceived by instrument comes from the emission of underground object. Because of the complexity of the source and exploration situation, it’s necessary for the received original ULF data to be filtered in order to get the clearer exploration curves which are less jammed. The exploration result of Tacan No.1 Well in Tarim Basin shows that the passive ULF technique can gain the deep geological information rapidly and accurately.

Key words: natural electromagnetic field, ultra-lowfrequency, deep geology, zero magnetic field, power-line interference, notch filter

摘要： 对被动式超低频电磁探测技术的场源问题、噪声的滤除，以及超低频电磁波与地下物质相互作用机理进行了探讨和实验。零磁场实验表明传感器在地面接收的超低频电磁波来 自地下地层等地质体的辐射。由于场源和探测环境的复杂性，对传感器接收的原始超低频电磁波数据进行软、硬件滤波处理，消除工频干扰和随机噪声，得到了干扰影响小的探测曲线。塔里木塔参1 井的探测试验表明，被动式超低频电磁探测技术可以快速准确的探测深部地质信息。

关键词: 天然电磁场, 超低频, 深部地质, 零磁场, 工频干扰, 陷波器