多辐射场源地空瞬变电磁法多分量全域视电阻率定义  

Multi-component full field apparent resistivity definition of multi-source ground-airborne transient electromagnetic method with galvanic sources

作　　者：张莹莹[1] 李貅[1] 姚伟华[1] 智庆全 李佳[1] 

机构地区：[1]长安大学地质工程与测绘学院,西安710054

出　　处：《地球物理学报》2015年第8期2745-2758,共14页Chinese Journal of Geophysics

基　　金：国家重大科研设备研制项目(ZDYZ2012-1-05-04);国家自然科学基金面上项目(41174108)联合资助

摘　　要：本文针对多辐射场源地空瞬变电磁法理论,建立了相应的多分量全域视电阻率定义方法.分析了利用磁场强度进行多辐射场源地空系统全域视电阻率定义的优点,针对磁场强度的各个分量,提出了各自的全域视电阻率算法,实现了多分量、全时域、全空域视电阻率计算,并分析了偏移距对全域视电阻率的影响.通过调整源的相对位置及电流方向等参数,多辐射源瞬变电磁地空系统不仅可以加强不同分量信号强度,削弱随机干扰,还可更好地分辨地下异常体的位置.通过对所设计模型的处理,证实了多辐射场源地空系统多分量全域视电阻率算法的有效性,也验证了多辐射场源地空系统的优势.Multi-source ground-airborne transient electromagnetic method with galvanic sources has such advantages as strengthening signal intensity,weakening random disturbance,better identifying the position of geological abnormity,etc.However,so far its interpretation method has not been established yet,which restricts the development of this method.This paper chooses the most widely used interpretation parameter-apparent resistivity in our research and builds up multi-component full field apparent resistivity algorithm for multi-source ground-airborne transient electromagnetic method with galvanic sources,which provides an effective and practical interpretation tool for this method.This paper analyzes the advantages of magnetic field intensity in multi-source groundairborne transient electromagnetic interpretation and puts forward multi-source and multicomponent full field apparent resistivity algorithm for each component on the basis of inverse function theorem and iterative method.The results of theoretical models show that the first and last part of the apparent resistivity curve can reach the resistivity of the first and the last layer,respectively.Thus,multi-component,full time and full space apparent resistivity definition is achieved.The results of layered models show that：（1）Full field apparent resistivity can tell the underground electric change smoothly,completely and gradually.（2）When the resistivity of layered model changes,the differentiation of full field apparent resistivity is obvious,which can easily and intuitively identify electric layer.（3）With the change of offset,the difference among apparent resistivity curves of each component is small and they all reflect subsurface structure well.（4）As receiver altitude,offset and time are considered simultaneously in our calculation,full field apparent resistivity can achieve full space and full time apparent resistivity calculation.The results of three dimensional model with a low-resistivity anomaly show that：（1）By changing spatial lo

关 键 词：多辐射场源 多分量 地空系统 全域视电阻率 

分 类 号：P631[天文地球—地质矿产勘探]