SN388系统易产生“串感应”的原因分析及规避方法探讨

地震勘探仪器受到外界电磁感应的干扰而在地震记录中产生所谓的"串感应"现象,是多年来一直困扰地震勘探数据采集质量的老问题,这个问题在SN388仪器上尤为突出、严重。几年来,已有不少技术人员花费了大量的时间和精力来应对这一问题。"串感应"的产生机理是十分复杂的,本文另辟蹊径,对"串感应"产生的原因给出了另外一种解释:地震排列感生LC回路满足谐振条件而同时发生谐振。通过分析SN388采集系统数传电缆的结构及检波器串所构成的LC振荡回路的特点来论述SN388采集系统为何容易出现感应,以及感应与检波器串的灵敏度、检波器漏磁量之间的关系:检波器串的灵敏度和漏磁量越高,越容易产生"串感应"。最后文章通过实际试验,证明了本文的观点,并针对SN388采集系统提出了在生产过程中规避感应的几种方法和措施。

Analysis of reason of "string induction" produced easily in SN388 and discussion on dodge method

So-called "string induction" produced in seismic records when seismograph suffered from the interference of outside electromagnetic induction is old problem that always has influence on acquisition quality of seismic data for many years,which is especially conspicuous and serious for SN388 seismograph.In recent years,there have been many technicians who have spent a lot of time and energy in probing this problem.The produced mechanism of "string induction" is very complicated.The paper,using other way,gave different interpretation for the reason the "string induction" produced: the LC loop the seismic spread produced by induction meets the harmonic condition and produces harmonic at the same time.We expounded why does the SN388 acquisition system easily produce induction by analyzing the structure of digital transmission cable of SN388 acquisition system and the character of LC oscillatory loop constituted by geophone strings and discussed the relationship among the induction,sensibility of geophone string and magnetic leakage flux of geophone,resulted in that the higher the sensibility and magnetic leakage flux of geophone,the easier production of "string induction".At the end of the article,we proved the view of the paper by using the practical tests and proposed several approaches and measures avoiding induction in a process of production for SN388 acquisition system.