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电性源瞬变电磁激电效应的正反演方法技术研究

发布时间:2018-10-15 18:38
【摘要】:当地下存在极化体时,瞬变电磁响应中包含了激发极化效应,在测量中可能会出现负电磁响应,这种IP效应已被大量的研究、实践工作证实。由于人工源“长偏移距”的激电法本质上和天然场源激电法一样,都是在“远区场”中作激电观测,电磁感应占绝对优势,要提取被强大的电磁效应异常“淹没”的弱小激电异常难度极大,其前景不乐观。与频率域电磁法相比,时间域电磁法可实现短偏移距甚至零偏移距探测。与回线源相比,电性源具有更大的探测深度,且既可观测磁场分量也可观测电场分量。因此,研究电性源瞬变电磁响应受激电效应的影响特征和规律,以及提取激电信息的方法,有助于解决深部大型矿床(藏)含矿信息。本文简要介绍了Cole-Cole模型的由来,通过基于Cole-Cole模型的电性源瞬变电磁一维正演计算,分析了极化体电阻率及装置收发距对激电效应的影响规律。通过均匀半空间模型分析了Cole-Cole模型各参数对瞬变电磁场各分量(xHyE和、????tHt z)的影响规律,研究发现,极化率参数对电磁场响应的影响最大,频率相关系数的影响次之,时间常数的影响最小。对三层地电模型进行了模拟试算,结果表明,不同类型的地电模型受到激电效应影响的程度不同,极化层为相对低阻层时受激电效应的影响最大。对比CSAMT法和电性源瞬变电磁法受激电效应的影响特点,发现利用电性源瞬变电磁法提取激电信息更有前景。本文利用磁场强度和感应电动式两种方法定义了全区视电阻率,并讨论了激电效应对两种视电阻率曲线的影响规律。本文通过改进的阻尼最小二乘法,对模型进行全参数反演(同时反演电阻率,厚度,极化率,频率相关系数和时间常数五个参数),初始模型选取合适时,反演结果较理想,但全参数反演模型参数太多,反演结果受初始模型影响很大,若初始模型选取不合适,则得不到合理的结果。本文中基于水平磁场分量的时间导数受激电效应影响小,而且激电效应影响的主要参数是极化率,通过固定频率相关系数和时间常数,反演其它三个参数的结果作为初始模型,再利用垂直磁场分量的时间导数进行全参数反演,可得到较理想的结果。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。理论研究结果表明,电性源TEM激电效应是显著的、可提取的,反演结果与实际参数基本吻合。
[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.
【学位授予单位】:长安大学
【学位级别】:硕士
【学位授予年份】:2015
【分类号】:P631.325

【参考文献】

相关期刊论文 前10条

1 罗延钟,张胜业,熊彬;天然场源激电法的可行性[J];地球物理学报;2003年01期

2 白登海,Maxwell A Meju,卢健,王立凤,何兆海;时间域瞬变电磁法中心方式全程视电阻率的数值计算[J];地球物理学报;2003年05期

3 殷长春,,刘斌;瞬变电磁法三维问题正演及激电效应特征研究[J];地球物理学报;1994年S2期

4 严良俊,胡文宝,陈清礼,胡家华;长偏移距瞬变电磁测深法在碳酸盐岩覆盖区落实局部构造的应用效果[J];地震地质;2001年02期

5 翁爱华,王雪秋;长偏移距瞬变电磁测深甚晚期响应及视电阻率的数值计算[J];地震地质;2003年04期

6 刘磊;昌彦君;曹中林;;可极化大地上CSAMT激发极化效应的研究[J];工程地球物理学报;2008年06期

7 余传涛;刘鸿福;张新军;杨德义;李白红;;从瞬变电磁响应中提取IP信息的研究(英文)[J];Applied Geophysics;2013年01期

8 陈明生,解海军;电偶源瞬变电磁测深研究(三)——大地表面瞬变电磁场[J];煤田地质与勘探;1999年03期

9 陈明生,田小波;电偶源瞬变电磁测深研究(四)——瞬变电磁测深视电阻率[J];煤田地质与勘探;1999年04期

10 孙鸿雁;磁性源瞬变电磁测量中激电效应作用规律的探讨[J];物探与化探;1998年01期

相关硕士学位论文 前2条

1 邱宁;瞬变电磁信号的预处理和激电效应识别研究[D];中国地质大学;2007年

2 黄磊;CSAMT中的IP效应提取[D];中南大学;2009年



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