EH-4系统观测资料的非远区场校正研究

STUDY OF THE NONFARZONE FIELD CORRECTION FOR THE SOUNDING DATA OF THE EH-4 SYSTEM

EH - 4系统实测的卡尼亚视电阻率在非远区场时应作必要的校正。基于导出的EH - 4系统的卡尼亚电阻率 ρxy和 ρyx的表达式 ,采用多项式分段逼近的方法 ,建立EH - 4系统测深数据的全频域的视电阻率算法。根据建立的算法对均匀大地、二层大地和三层大地模型的EH - 4系统测深数据进行非远区场校正的结果表明 :均匀大地时 ,全频域的视电阻率与真电阻率吻合很好 ,D型、K型和Q型断面的视电阻率曲线与MT法的接近 ,G型、H型和A型的视电阻率曲线得到很大改善。

It is necessary to perform a correction for the Cagniard resistivity of the non far zone field obtained by the EH-4 electrical conductivity image forming system. Based on the derived expressions of ρ xy and ρ yx , using polynomial segmental approach, the correction method for the non far zone field is established by calculating the full frequency domain apparent resistivity. The correction results are showed below: firstly, under the uniform telluric condition, the apparent resistivity is almost identical with the telluric real resistivity in the whole frequency range; secondly, under the stratified telluric condition, the resistivity curves of the D type, K type and Q type are very close to that of the MT method, and curves of the G type, H type and A type can vividly reflect the corresponding geo electric sections.