【摘要】：當(dāng)?shù)叵麓嬖跇O化體時(shí),瞬變電磁響應(yīng)中包含了激發(fā)極化效應(yīng),在測量中可能會(huì)出現(xiàn)負(fù)電磁響應(yīng),這種IP效應(yīng)已被大量的研究、實(shí)踐工作證實(shí)。由于人工源“長偏移距”的激電法本質(zhì)上和天然場源激電法一樣,都是在“遠(yuǎn)區(qū)場”中作激電觀測,電磁感應(yīng)占絕對(duì)優(yōu)勢,要提取被強(qiáng)大的電磁效應(yīng)異�！把蜎]”的弱小激電異常難度極大,其前景不樂觀。與頻率域電磁法相比,時(shí)間域電磁法可實(shí)現(xiàn)短偏移距甚至零偏移距探測。與回線源相比,電性源具有更大的探測深度,且既可觀測磁場分量也可觀測電場分量。因此,研究電性源瞬變電磁響應(yīng)受激電效應(yīng)的影響特征和規(guī)律,以及提取激電信息的方法,有助于解決深部大型礦床(藏)含礦信息。本文簡要介紹了Cole-Cole模型的由來,通過基于Cole-Cole模型的電性源瞬變電磁一維正演計(jì)算,分析了極化體電阻率及裝置收發(fā)距對(duì)激電效應(yīng)的影響規(guī)律。通過均勻半空間模型分析了Cole-Cole模型各參數(shù)對(duì)瞬變電磁場各分量(xHyE和、????tHt z)的影響規(guī)律,研究發(fā)現(xiàn),極化率參數(shù)對(duì)電磁場響應(yīng)的影響最大,頻率相關(guān)系數(shù)的影響次之,時(shí)間常數(shù)的影響最小。對(duì)三層地電模型進(jìn)行了模擬試算,結(jié)果表明,不同類型的地電模型受到激電效應(yīng)影響的程度不同,極化層為相對(duì)低阻層時(shí)受激電效應(yīng)的影響最大。對(duì)比CSAMT法和電性源瞬變電磁法受激電效應(yīng)的影響特點(diǎn),發(fā)現(xiàn)利用電性源瞬變電磁法提取激電信息更有前景。本文利用磁場強(qiáng)度和感應(yīng)電動(dòng)式兩種方法定義了全區(qū)視電阻率,并討論了激電效應(yīng)對(duì)兩種視電阻率曲線的影響規(guī)律。本文通過改進(jìn)的阻尼最小二乘法,對(duì)模型進(jìn)行全參數(shù)反演(同時(shí)反演電阻率,厚度,極化率,頻率相關(guān)系數(shù)和時(shí)間常數(shù)五個(gè)參數(shù)),初始模型選取合適時(shí),反演結(jié)果較理想,但全參數(shù)反演模型參數(shù)太多,反演結(jié)果受初始模型影響很大,若初始模型選取不合適,則得不到合理的結(jié)果。本文中基于水平磁場分量的時(shí)間導(dǎo)數(shù)受激電效應(yīng)影響小,而且激電效應(yīng)影響的主要參數(shù)是極化率,通過固定頻率相關(guān)系數(shù)和時(shí)間常數(shù),反演其它三個(gè)參數(shù)的結(jié)果作為初始模型,再利用垂直磁場分量的時(shí)間導(dǎo)數(shù)進(jìn)行全參數(shù)反演,可得到較理想的結(jié)果。在反演中加入了可行方向,一定程度上抑制了反演的多解性。理論研究結(jié)果表明,電性源TEM激電效應(yīng)是顯著的、可提取的,反演結(jié)果與實(shí)際參數(shù)基本吻合。
[Abstract]:When the polarizer exists underground, the induced polarization effect is included in the transient electromagnetic response, and the negative electromagnetic response may occur in the measurement. This IP effect has been studied and proved in practice. As the "long offset" method of artificial source is essentially the same as the natural field source method, it is observed in the "far field", and electromagnetic induction is the absolute predominance. It is very difficult to extract the weak and weak IP anomaly which is "submerged" by the strong electromagnetic effect anomaly, and its prospect is not optimistic. Compared with frequency domain electromagnetic method, time domain electromagnetic method can detect short offset or zero offset. Compared with the loop source, the electric source has a greater detection depth and can be observed both in magnetic field and in electric field. Therefore, it is helpful to study the characteristics and rules of the transient electromagnetic response of electric source and the method of extracting the information of induced electromagnetism, which is helpful to solve the ore-bearing information of deep large deposits (reservoirs). In this paper, the origin of Cole-Cole model is briefly introduced. Through the one-dimensional forward calculation of electric source transient electromagnetic based on Cole-Cole model, the influence of polarization resistivity and device transceiver distance on the induced electric effect is analyzed. The effects of parameters of Cole-Cole model on the components of transient electromagnetic field (xHyE and,? tHt z) are analyzed by the uniform half-space model. It is found that the polarizability parameters have the greatest influence on the electromagnetic field response, and the frequency correlation coefficient is the second. The influence of time constant is minimal. The three layer geoelectric model is simulated and calculated. The results show that different geoelectric models are affected by the induced electric effect to different extent, and the polarization layer is the relatively low resistivity layer, which is the most affected by the induced electric effect. By comparing the characteristics of CSAMT method and electric source transient electromagnetic method under the influence of induced electric effect, it is found that it is more promising to extract the IP information by using the electric source transient electromagnetic method. In this paper, the whole area apparent resistivity is defined by magnetic field intensity and inductive electric type, and the influence of induced electric effect on the two apparent resistivity curves is discussed. In this paper, the modified damped least square method is used to invert the whole parameters of the model (resistivity, thickness, polarizability, frequency correlation coefficient and time constant). When the initial model is suitable, the inversion results are satisfactory. But the full parameter inversion model has too many parameters, and the inversion result is greatly affected by the initial model. If the initial model is not suitable, there is no reasonable result. In this paper, the time derivative based on the horizontal magnetic field component has little effect on the induced electric effect, and the main parameter affected by the induced electric effect is polarizability. By using the fixed frequency correlation coefficient and the time constant, the results of the other three parameters are retrieved as the initial model. Using the time derivative of the vertical magnetic field component to carry out the full parameter inversion, the ideal results can be obtained. The feasible direction is added to the inversion, which to some extent inhibits the multi-solvability of the inversion. The theoretical results show that the TEM induced effect of the electrical source is significant and can be extracted, and the inversion results are in good agreement with the actual parameters.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P631.325

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