摘要
对井下地电阻率观测的探测深度进行了研究,计算了均匀半空间和给定结构参数的水平层状介质模型在不同装置电极埋深下的探测深度,分析了探测深度与装置电极埋深和介质电阻率结构之间的关系,得到如下结果:1与地表观测相比,在供电极距为1km左右时,探测深度随装置电极埋深的增大而增大,且增大的速度与装置电极埋深密切相关;当装置电极埋深h<100m时,探测深度的增大速度远小于装置电极埋深h≥100m时.2当装置电极埋深h<50m时,与地表观测相比探测深度增加很小,不超过10m;当装置电极埋深相同时,供电极距越大,与地表观测相比探测深度增加得越小.3对于水平层状电阻率均匀分层结构,在装置电极埋深相同的情况下,下伏低阻结构的探测深度显著大于下伏高阻结构.本文的研究结果表明,为了观测到深部电阻率的变化情况,首先需要查明测区电性结构,再进行综合分析,以确定井下地电阻率观测的装置电极埋深,其结果为深部电阻率变化研究提供了理论基础.
In this paper, we studied probing depths of borehole geoelectrical resistivity observation by homogeneous half-space model and horizontally layered model with given structure parameters, and analyzed the relationship among probing depth, electrode buried depth of configuration and medium resistivity structure. The results are as follows: (1) Compared with surface observa- tion, when electrode distance is about 1 km, probing depth increases with electrode buried depth of configuration, and the increasing rate is closely related with electrode buried depth, as the increasing rate of electrode buried depth less than 100 m is much smaller than that greater than 100 m. (2) When electrode buried depth of configuration is within 50 m, probing depth has a slow increase which is less than 10 m, compared with surface observation. For the same electrode buried depth, the greater electrode distance is, the smaller probing depth increases. (3) For the horizontally layered structure of homogeneous resistivity, probing depth in underlying low resistivity structure is significantly larger than that in underlying high resistivity structure under the condition of same electrode buried depth of configurations. Therefore, in order to observe the resistivity variations of deep medium, it is necessary to firstly identify the electrical structure parameters of observation area, and then determine electrode buried depth of borehole geoelectrical resistivity observation through comprehensive analyses.
出处
《地震学报》
CSCD
北大核心
2017年第2期230-238,共9页
Acta Seismologica Sinica
基金
中国地震局地震科技星火计划(XH16034)资助
关键词
地电阻率
井下观测
探测深度
装置电极埋深
geoelectrical resistivity
electrode buried depth of configuration borehole observation
probing depth