The Study Of Improving The Calculating Precious Of Appearent Resistivity And Data Process Interpretion Systerm In FEM Methods

The study on how to improve the accurary of the FEM methods'apparent resistivity and the data's process and interpretation is emphasize in this thesis, which can be give the guides for the fieldwork and the data process.The apparent resistivity can be used to calculate the stratum's resistivity through the ratio of Ey to Ex in the far-field, which needed the distant between the transmitter and receiver far. Because the attenuation of the electromagnetic field power is inverse ratio to the distance'power from 3 to4 between the transmitter and receiver, and the transmitter signal's attenuation soon ,and the receive signal weak, the transmit power is so strong ,receive precise is so high ,the instrument is so heavy, sometimes the request about the filed is so high that the reconnaissance survey for mining is too hard to practice. If the survey is in near-field, the distant is short, and the transmit power is enough small to be received good. And the instrument is not too heavey. A FEM method which is introduced by J.Dulics France is base on the near-field survey value multiplyed by the revise coefficient K which can by vary by the ,γγ(circle wave multiply by the distance between the transmitter and the receiver) ,so the far-field which is calculated by the differentγγcan be used to calculate the apparent resistivity.The precise of approximative formula on K and K'is too low to affectto calculate the apparent resistivity, now I introduce a multinomial fit method to improve the precise of apparent resistivity and to improve the data interpretation level.And so ,five practice steps on the data process and FEM fingers plotted is introduced, first the apparent resistivity is calculated, second the curve type compare figure is plotted, third p-f section plane figure is plotted ,forthρa—f isoline plan is plotted( some frequency), fifths the quantitative interpretation with the FEM 1-D inversion soft is done. From above, The work is done wonderfully with the integrate interpretation.The FEM's virtue with four examples about its application scale and condition is summarized in this chapter.Some results of FEM in the geology exploration from the practices is summed up as fellow:First, The study on the K,K'coefficient with the use of least quadratic method to calculate is to improve the precise of the apparent resistivity, and so improve the precise and the reliability on the geology interpretation.Second The five steps summarized from practice will give good instructedness to the practice work..Third the application scale and condition of the FEM with the practice work and the virtue and disadvantage of FEM is put forward.