發(fā)布時(shí)間：2018-11-24 12:04

【摘要】：可控源大地電磁法(CSAMT)是在大地電磁法和音頻大地電磁法的基礎(chǔ)上發(fā)展起來(lái)的人工源電磁勘探方法。由于發(fā)射源的強(qiáng)度相對(duì)于天然場(chǎng)源信號(hào)強(qiáng)度明顯增強(qiáng),對(duì)針對(duì)目標(biāo)體的勘探分辨能力提高,觀測(cè)電磁場(chǎng)值所需的時(shí)間大大減少,所以該方法具有較高的生產(chǎn)效率。但是,由于場(chǎng)源的引入,相對(duì)與大地電磁測(cè)深方法,在數(shù)值模擬,特別是三維問(wèn)題的模擬上難度較大。同時(shí),由于源的引入,也帶來(lái)了一些其他的問(wèn)題,如近場(chǎng)效應(yīng)、陰影效應(yīng)和復(fù)印效應(yīng)等。如何提高CSAMT方法的應(yīng)用效果,克服場(chǎng)源效應(yīng)帶來(lái)的解釋誤差,是當(dāng)前該領(lǐng)域的研究熱點(diǎn),也是研究難點(diǎn)。因此,發(fā)展針對(duì)三維場(chǎng)源的二維、三維可控源電磁法數(shù)值模擬是非常有必要的。本文從麥克斯韋方程出發(fā),完成了三維交錯(cuò)網(wǎng)格有限差分方法的理論和公式推導(dǎo)。為消除源點(diǎn)處場(chǎng)值的奇異性,把電場(chǎng)分為一次場(chǎng)和二次場(chǎng)分別進(jìn)行計(jì)算。一次場(chǎng)通過(guò)解析方法進(jìn)行求解,二次場(chǎng)的二階偏微分方程通過(guò)Yee氏交錯(cuò)網(wǎng)格進(jìn)行有限差分離散。為節(jié)省內(nèi)存空間,形成的稀疏對(duì)稱復(fù)系數(shù)線性方程組采用行壓縮格式(CSR)進(jìn)行存儲(chǔ),并使用對(duì)稱擬最小殘差法(SQMR)求解。用C++語(yǔ)言實(shí)現(xiàn)了三維正演程序,并驗(yàn)證了程序的正確性。最后計(jì)算了典型三維模型的響應(yīng),并對(duì)近場(chǎng)效應(yīng)、陰影效應(yīng)和復(fù)印效應(yīng)進(jìn)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.
【學(xué)位授予單位】：成都理工大學(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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本文編號(hào)：2353643