可控源音频大地电磁法三维有限差分正演模拟及场源效应研究
发布时间：2018-11-24 12:04
【摘要】：可控源大地电磁法(CSAMT)是在大地电磁法和音频大地电磁法的基础上发展起来的人工源电磁勘探方法。由于发射源的强度相对于天然场源信号强度明显增强,对针对目标体的勘探分辨能力提高,观测电磁场值所需的时间大大减少,所以该方法具有较高的生产效率。但是,由于场源的引入,相对与大地电磁测深方法,在数值模拟,特别是三维问题的模拟上难度较大。同时,由于源的引入,也带来了一些其他的问题,如近场效应、阴影效应和复印效应等。如何提高CSAMT方法的应用效果,克服场源效应带来的解释误差,是当前该领域的研究热点,也是研究难点。因此,发展针对三维场源的二维、三维可控源电磁法数值模拟是非常有必要的。本文从麦克斯韦方程出发,完成了三维交错网格有限差分方法的理论和公式推导。为消除源点处场值的奇异性,把电场分为一次场和二次场分别进行计算。一次场通过解析方法进行求解,二次场的二阶偏微分方程通过Yee氏交错网格进行有限差分离散。为节省内存空间,形成的稀疏对称复系数线性方程组采用行压缩格式(CSR)进行存储,并使用对称拟最小残差法(SQMR)求解。用C++语言实现了三维正演程序,并验证了程序的正确性。最后计算了典型三维模型的响应,并对近场效应、阴影效应和复印效应进行了分析。
[Abstract]:Controllable source magnetotelluric method (CSAMT) is an artificial electromagnetic exploration method developed on the basis of magnetotelluric method and audio magnetotelluric method. Because the intensity of emission source is obviously stronger than that of natural field source, the resolution of exploration for target is improved, and the time required to observe electromagnetic field value is greatly reduced, the method has higher production efficiency. However, because of the introduction of the field source, it is difficult to simulate the numerical simulation, especially the three-dimensional problem, relative to the magnetotelluric sounding method. At the same time, the introduction of the source also brings some other problems, such as near-field effect, shadow effect and photocopying effect. How to improve the application effect of CSAMT method and overcome the interpretation error caused by field source effect is a hot and difficult research topic in this field. Therefore, it is necessary to develop two-dimensional and three-dimensional controlled source electromagnetic simulation for three-dimensional field sources. In this paper, the theory and formula of three dimensional staggered grid finite difference method are derived from Maxwell's equation. In order to eliminate the singularity of the field value at the source point, the electric field is divided into the primary field and the quadratic field respectively. The first order field is solved by analytical method, and the second order partial differential equation of quadratic field is discretized by Yee's staggered grid. In order to save memory space, the sparse symmetric linear equations with complex coefficients are stored in row compression format (CSR) and solved by symmetric quasi minimum residual method (SQMR). The three-dimensional forward program is realized with C language, and the correctness of the program is verified. Finally, the responses of typical 3D models are calculated, and the near-field effects, shadow effects and photocopying effects are analyzed.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.325
本文编号：2353643
[Abstract]:Controllable source magnetotelluric method (CSAMT) is an artificial electromagnetic exploration method developed on the basis of magnetotelluric method and audio magnetotelluric method. Because the intensity of emission source is obviously stronger than that of natural field source, the resolution of exploration for target is improved, and the time required to observe electromagnetic field value is greatly reduced, the method has higher production efficiency. However, because of the introduction of the field source, it is difficult to simulate the numerical simulation, especially the three-dimensional problem, relative to the magnetotelluric sounding method. At the same time, the introduction of the source also brings some other problems, such as near-field effect, shadow effect and photocopying effect. How to improve the application effect of CSAMT method and overcome the interpretation error caused by field source effect is a hot and difficult research topic in this field. Therefore, it is necessary to develop two-dimensional and three-dimensional controlled source electromagnetic simulation for three-dimensional field sources. In this paper, the theory and formula of three dimensional staggered grid finite difference method are derived from Maxwell's equation. In order to eliminate the singularity of the field value at the source point, the electric field is divided into the primary field and the quadratic field respectively. The first order field is solved by analytical method, and the second order partial differential equation of quadratic field is discretized by Yee's staggered grid. In order to save memory space, the sparse symmetric linear equations with complex coefficients are stored in row compression format (CSR) and solved by symmetric quasi minimum residual method (SQMR). The three-dimensional forward program is realized with C language, and the correctness of the program is verified. Finally, the responses of typical 3D models are calculated, and the near-field effects, shadow effects and photocopying effects are analyzed.
【学位授予单位】：成都理工大学
【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2条
1 陈明生,闫述;CSAMT勘探中场区、记录规则、阴影及场源复印效应的解析研究[J];地球物理学报;2005年04期
2 刘瑞德;黄力军;孟银生;;可控源音频大地电磁测深法在地热田勘查中应用效果初探[J];工程地球物理学报;2007年02期
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