天然电场选频法的浅层地下水勘探效果与异常分析
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摘要
通过实践应用、理论推导和模拟计算,说明天然电场选频法在浅层地下水勘探中的有效性,并分析其异常形成过程中起主要作用的天然一次场场源分量。将选频法应用于广西农村找水打井项目中,依据其勘探成果共钻井131口,出水量大于1 m3/h的井共114口,约占钻井总量的87%。实践表明选频法在浅层地下水勘探中是实用可行的。在实践应用和以往研究成果的基础上,设计均匀半空间内球形充水岩溶的简单模型,以便解析求解并计算分析地表主剖面上二次电场的大小;计算结果表明,水平交变磁场产生的二次电场是一个相对高电位异常,而水平交变电场才产生相对低电位异常,由此推断天然电场选频法在地下水勘探中异常的形成主要是由于地下天然交变电场分量作用的结果。
Through practical application,theoretical deduction and simulation calculation,the validity of the frequency selection method of natural electric field in shallow groundwater exploration was illustrated,and the natural field source component which plays a major role in the formation of anomaly was analyzed. The method had been applied to 12 th Five-Year Plan of the rural drinking water safety project by No. 273 Geological Party of Guangxi in 2013 ～ 2015. According to its exploration results,a total of 131 wells were drilled.114 wells' water output was more than 1 m3/h,accounting for about 87.0% of the total amount of drill holes. The practical application shows that the frequency selection method is practical and feasible in shallow groundwater exploration. On the basis of practical application and previous research results,a spherical water filled karst model in uniform half space was designed,and the magnitude of the secondary electric field on the main section of the surface was calculated by using analytic method. The calculated results show that the horizontal alternating magnetic field produces a relatively high potential anomaly,whereas the horizontal alternating electric field produces a relatively low potential anomaly. It can be concluded that the formation of anomaly of frequency selection method in groundwater exploration is mainly due to the effect of alternating electric field components.
Through practical application,theoretical deduction and simulation calculation,the validity of the frequency selection method of natural electric field in shallow groundwater exploration was illustrated,and the natural field source component which plays a major role in the formation of anomaly was analyzed. The method had been applied to 12 th Five-Year Plan of the rural drinking water safety project by No. 273 Geological Party of Guangxi in 2013 ～ 2015. According to its exploration results,a total of 131 wells were drilled.114 wells' water output was more than 1 m3/h,accounting for about 87.0% of the total amount of drill holes. The practical application shows that the frequency selection method is practical and feasible in shallow groundwater exploration. On the basis of practical application and previous research results,a spherical water filled karst model in uniform half space was designed,and the magnitude of the secondary electric field on the main section of the surface was calculated by using analytic method. The calculated results show that the horizontal alternating magnetic field produces a relatively high potential anomaly,whereas the horizontal alternating electric field produces a relatively low potential anomaly. It can be concluded that the formation of anomaly of frequency selection method in groundwater exploration is mainly due to the effect of alternating electric field components.
引文
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[3]李立.磁大地电流法和大地电流—大地电流剖面法[J].物探与化探,1983,7(4):194-198.
[4]鲍光淑,李大庆,张友山,等.干扰电场仪的研究[J].中国有色金属学报,1994,4(4):9-13.
[5]杨天春,张辉.利用天然电场选频法研究断层接触带[J].湖南科技大学学报:自然科学版,2013,28(4):32-37.
[6]杨天春,申建平,黎光明,等.天然电场选频法在充水岩溶勘查中的试验与分析[J].煤田地质与勘探,2014,42(2):71-75.
[7]杨天春,张启,王齐仁,等.天然电磁场激励下球体的天然电场选频法异常成因分析[J].湖南科技大学学报:自然科学版,2016,31(2):58-65.
[8]程辉,白宜诚.天然音频电场选频仪设计与应用[J].地球物理学进展,2014,29(6):2874-2879.
[9]梁竞,韦启锋,洪卷,等.自然电场法在岩溶地区找水打井中的应用[J].工程勘察,2016,44(2):68-78.
[10]杨天春,张辉.岩溶体的天然电场选频法异常成因研究[J].水文地质工程地质,2013,40(5):22-28.
[11]林君琴,雷长声,董启山.天然低频电场法[J].长春地质学院学报,1983,13(2):114-126.
[12]杨天春,夏代林,王齐仁,等.天然电场选频法理论研究与应用[M].长沙:中南大学出版社,2017.
[13]汤井田,周聪,肖晓.复杂介质条件下CSAMT最小发收距的选择[J].中国有色金属学报,2013,23(6):1681-1693.
[14] Ward S H.地球物理用电磁理论[M].北京:地质出版社,1978.
[15]何继善.海洋电磁法原理[M].北京:高等教育出版社,2012.
[16]杨杰.游散电流法在岩溶地区的试验成果及理论研究[J].物探与化探,1982,6(1):41-54.