本文選題：瞬變電磁 + 中心回線�。� 參考：《西安科技大學(xué)》2017年碩士論文

【摘要】：瞬變電磁法(TEM)勘探裝置類型眾多,其中的中心回線裝置效率高,優(yōu)點(diǎn)突出,在工程找礦、煤礦水害預(yù)測等方面應(yīng)用廣泛。然而瞬變電磁施工時,在關(guān)斷時間內(nèi)一次場與二次場混疊,導(dǎo)致早期數(shù)據(jù)發(fā)生畸變,無法獲取準(zhǔn)確的淺部地層信息,給全期視電阻率的反演解釋帶來很大影響。為了獲取地層在深度上視電阻率的連續(xù)變化特征,依據(jù)瞬變電磁中心回線裝置均勻半空間電偶極子脈沖激發(fā)的垂直磁場理論,以線性斜階躍電流關(guān)斷起點(diǎn)為延遲采樣零時刻的電偶源垂直磁場為例,根據(jù)單位脈沖響應(yīng)函數(shù)的性質(zhì),本文將關(guān)斷時間內(nèi)線性斜階躍的脈沖響應(yīng)剖分為一系列垂直脈沖響應(yīng)之和,建立起正演磁場響應(yīng)和實(shí)測感應(yīng)電動勢轉(zhuǎn)化的磁場響應(yīng)之間的方程,再設(shè)置電阻率范圍,采用優(yōu)化的迭代算法計(jì)算出全期視電阻率,這樣就可以解決關(guān)斷時間對磁場的影響。通過對均勻半空間、兩層模型、三層模型和四層模型不同參數(shù)下的地電模型進(jìn)行數(shù)值模擬,驗(yàn)證了均勻半空間及多層介質(zhì)模型的大地表面一維瞬變電磁正演程序的準(zhǔn)確性,并總結(jié)出了各模型在參數(shù)變化時的磁場響應(yīng)變化規(guī)律,對實(shí)際資料的解釋有一定的參考價(jià)值。根據(jù)建立的全期視電阻率計(jì)算模型,本文編寫了一維全期視電阻率計(jì)算程序,并對各地電模型的正演瞬變電磁響應(yīng)進(jìn)行反演,繪制全期視電阻率剖面圖,再與正演計(jì)算出的全期視電阻率曲線和晚期公式計(jì)算的視電阻率曲線作對比。結(jié)果表明由本文模型計(jì)算出的全期視電阻率曲線能夠與正演地電模型基本重合,而晚期視電阻率曲線在早期的視電阻率值偏大,不適合做全期解釋。最后將研究成果應(yīng)用于瞬變電磁實(shí)測資料的處理,并結(jié)合實(shí)際地質(zhì)資料對結(jié)果進(jìn)行驗(yàn)證。結(jié)果表明:全期視電阻率計(jì)算模型能夠準(zhǔn)確地反映出地層在深度方向的電阻率連續(xù)變化特征,且能夠解決關(guān)斷時間對磁場響應(yīng)的影響,提高了瞬變電磁勘探的分辨率。
[Abstract]:Transient electromagnetic method (TEM) is widely used in engineering prospecting, coal mine water hazard prediction and so on because of its high efficiency and outstanding advantages. However, in transient electromagnetic construction, the mixing of primary field and secondary field in turn-off time leads to the distortion of early data and the inability to obtain accurate shallow formation information, which has a great influence on the inversion interpretation of the whole period apparent resistivity. In order to obtain the continuous variation characteristics of apparent resistivity in depth, the vertical magnetic field theory of uniform half-space electric dipole pulse excitation of transient electromagnetic center loop device is used. Taking the linear oblique step current turn-off starting point as the delay sampling zero time vertical magnetic field as an example, according to the property of the unit pulse response function, In this paper, the pulse response of linear oblique step in turn-off time is divided into the sum of a series of vertical pulse responses, the equation between the forward magnetic field response and the magnetic field response of the measured induction electromotive force transformation is established, and the resistivity range is set up. The effect of turn-off time on the magnetic field can be solved by using the optimized iterative algorithm to calculate the apparent resistivity of the whole period. Through the numerical simulation of the geoelectric model in homogeneous half-space, two-layer model, three-layer model and four-layer model with different parameters, the accuracy of the one-dimensional transient electromagnetic forward program on the earth surface of homogeneous half-space and multi-layer media model is verified. The variation law of the magnetic field response of each model is summarized, which has some reference value for the interpretation of the actual data. According to the whole period apparent resistivity calculation model, the one-dimensional full-period apparent resistivity calculation program is compiled in this paper, and the forward transient electromagnetic response of the local electric model is inversed, and the whole period apparent resistivity profile is drawn. The results are compared with the full-period apparent resistivity curve calculated by the forward modeling and the apparent resistivity curve calculated by the late formula. The results show that the full term apparent resistivity curve calculated by this model can basically coincide with the forward geoelectric model, but the late apparent resistivity curve is too large in the early stage to be interpreted throughout the whole period. Finally, the research results are applied to the processing of transient electromagnetic measured data, and the results are verified with the actual geological data. The results show that the whole period apparent resistivity calculation model can accurately reflect the continuous variation characteristics of resistivity in depth direction, and can solve the effect of turn-off time on magnetic field response, and improve the resolution of transient electromagnetic exploration.
【學(xué)位授予單位】：西安科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P631.3

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本文編號：2112209