本文選題：大地電磁測(cè)深　切入點(diǎn)：靜態(tài)效應(yīng)　出處：《吉林大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：大地電磁測(cè)深法利用天然交變電磁場(chǎng)研究地球電性結(jié)構(gòu)，不受高阻層屏蔽，，對(duì)低阻層分辨率高。無需人工建立場(chǎng)源，施工方便，成本低廉，勘探深度范圍大，在能源、資源及深部地球物理勘探等領(lǐng)域得到了廣泛的應(yīng)用。 大地電磁測(cè)深法中存在一個(gè)普遍問題是數(shù)據(jù)中存在靜位移,亦即對(duì)數(shù)視電阻率-周期曲線相對(duì)于區(qū)域值有一個(gè)豎直方向上的平行移動(dòng)。這些靜位移是由于測(cè)點(diǎn)附近存在小規(guī)模，淺部導(dǎo)電性異常體。電荷在小于電磁場(chǎng)趨膚深度的近地表異常體上積累。這些積累電荷在觀測(cè)電場(chǎng)區(qū)域值的基礎(chǔ)上產(chǎn)生了一個(gè)持續(xù)到任意低頻率的擾動(dòng)。錯(cuò)誤的移除這些局部失真會(huì)導(dǎo)致反演解釋所要研究的深部目標(biāo)體時(shí)出現(xiàn)錯(cuò)誤。 電磁測(cè)深法的數(shù)據(jù)解釋和靜態(tài)效應(yīng)校正通常是分開處理的。對(duì)于同樣的實(shí)測(cè)數(shù)據(jù)不同的靜態(tài)校應(yīng)校正方法可能會(huì)得到不同的靜位移值，這樣一來，先移除數(shù)據(jù)中的靜位移再尋找一個(gè)擬合被處理過的數(shù)據(jù)的模型就存在一個(gè)風(fēng)險(xiǎn)，這個(gè)風(fēng)險(xiǎn)就是地電結(jié)構(gòu)推斷解釋中出現(xiàn)的異常可能是由于特定的靜位移選擇引起的。反演的同時(shí)校正靜態(tài)效應(yīng)的方法則可避免這個(gè)風(fēng)險(xiǎn)。 在一維情況下，對(duì)含有靜位移的大地電磁測(cè)深數(shù)據(jù)做反演解釋所獲得的模型和基于未失真數(shù)據(jù)得到的模型可能有一致的結(jié)構(gòu)，但視電阻率值和深度可能是錯(cuò)誤的。在二維和三維情況下，每個(gè)測(cè)點(diǎn)靜位移的量通常是不一樣的，當(dāng)試圖解釋含有靜態(tài)效應(yīng)的數(shù)據(jù)時(shí)可能會(huì)導(dǎo)致所獲得的模型中出現(xiàn)多余的結(jié)構(gòu)。在一些特殊情況下，甚至找不到擬合數(shù)據(jù)的模型。為了移除多余的粗糙度，可以在每個(gè)點(diǎn)引進(jìn)兩個(gè)靜位移參數(shù)用于縮放每個(gè)點(diǎn)TE和TM兩種模式的視電阻率，但相位數(shù)據(jù)不受影響。Occam反演可以在獲得最光滑模型的同時(shí)移除靜態(tài)效應(yīng)的影響。把靜位移當(dāng)作自由的參數(shù)參與到光滑模型反演中可以保證反演結(jié)果中出現(xiàn)的異常不只是由錯(cuò)誤的靜態(tài)效應(yīng)校正引起的。 本文在對(duì)當(dāng)前中外相關(guān)文獻(xiàn)收集和研讀的基礎(chǔ)上，對(duì)當(dāng)前大地電磁測(cè)深資料處理中經(jīng)常用到的靜態(tài)效應(yīng)校正手段進(jìn)行研究。對(duì)所建立的一些理論模型進(jìn)行了正演模擬，得出近地表局部不均勻體位于不同地電模型中時(shí)，兩種模式(TE，TM)的響應(yīng)特征。然后將靜位移作為一個(gè)反演參數(shù)直接參與反演，在反演過程中同時(shí)校正由地表局部不均勻體引起的靜態(tài)效應(yīng)。結(jié)果表明，利用靜態(tài)效應(yīng)的直接反演法來校正靜態(tài)效應(yīng)可以獲得不錯(cuò)的效果。 最后，用靜態(tài)效應(yīng)的直接反演法處理了本溪-集安地區(qū)的實(shí)測(cè)大地電磁測(cè)深資料。有效的消除了實(shí)測(cè)數(shù)據(jù)中含有的靜態(tài)效應(yīng)，使得反演解釋更加合理。
[Abstract]:The magnetotelluric sounding method uses natural alternating electromagnetic field to study the electrical structure of the earth, which is not shielded by the high resistivity layer, and has high resolution to the low resistivity layer. There is no need to establish the field source manually, the construction is convenient, the cost is low, the exploration depth range is large, and the exploration depth is in the energy source. Resources and deep geophysical exploration have been widely used. A common problem in magnetotelluric sounding is the existence of static displacement in the data. That is, the logarithmic apparent resistivity periodic curve has a vertical parallel movement relative to the regional value. These static displacements are due to the presence of small scales near the measured points. Shallow electrical conductivity anomaly. The charge accumulates on an anomaly near the surface that is smaller than the depth of the electromagnetic field. These accumulative charges produce a disturbance that persists to any low frequency on the basis of the observed electric field region. Removing these local distortions will lead to errors in the inversion interpretation of the deep object. Data interpretation and static effect correction of electromagnetic sounding methods are usually handled separately. Different static correction methods for the same measured data may result in different static displacement values. There is a risk of removing the static displacement from the data and then finding a model to fit the processed data. The risk is that the anomalies in the geoelectric structure inference interpretation may be caused by a particular static displacement selection, and this risk can be avoided by the method of inversion and correction of the static effect. In one dimensional case, the model derived from inversion interpretation of magnetotelluric sounding data with static displacement may have a consistent structure with the model based on undistorted data. But the apparent resistivity and depth can be wrong. In two and three dimensions, the amount of static displacement at each measuring point is usually different. When trying to interpret data with static effects, it may lead to redundant structures in the obtained model. In some special cases, no model can even be found to fit the data. In order to remove the excess roughness, Two static displacement parameters can be introduced at each point to scale the apparent resistivity of the te and TM modes at each point, But the phase data is unaffected. Occam inversion can remove the static effect while obtaining the smoothest model. Taking static displacement as a free parameter to participate in the smooth model inversion can ensure the anomalies in the inversion results. It is not just caused by incorrect static effect correction. In this paper, on the basis of the collection and study of the relevant literature at home and abroad, the static effect correction methods used frequently in the processing of magnetotelluric sounding data are studied, and the forward modeling of some theoretical models is carried out. The response characteristics of the two models in different geoelectric models are obtained, and the static displacement is taken as an inversion parameter to directly participate in the inversion. In the process of inversion, the static effects caused by local inhomogeneous bodies on the surface are corrected at the same time. The results show that the direct inversion method of static effects can get good results. Finally, the direct inversion method of static effect is used to deal with the measured magnetotelluric sounding data in Benxi-Ji'an area, which effectively eliminates the static effect in the measured data and makes the inversion interpretation more reasonable.
【學(xué)位授予單位】：吉林大學(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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