Approximate Interpretation of 3-D Data Using 2-D Inversion Program in the DC Resistivity Sounding
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摘要: 直流电阻率测深剖面数据解释最好的方法是二维反演, 这是由于它反演速度快, 而三维反演则需要很多的实测数据、很长的计算时间.而且通过对几种三维模型测深数据的二维反演结果的研究, 发现尽管对无走向的良导矿体, 二维反演方法所圈定的异常中心与真实矿体中心有一定的误差, 但基本上还是能反映矿体的真实形态和中心位置.当矿体具有一定的走向长度时, 则无论对高阻矿体还是良导矿体二维反演的效果都很好.Abstract: The 2-D inversion is the best method in the interpretation of DC resistivity sounding profiles data owing to its high speed, but the 3-D inversion, by contrast, needs more measured data and more computer time. Through the 2-D inversional study of several 3-D models, we know that for the good conductor ore-body without strike, there is some deflection between the center of real ore-body and the center of anomaly enclosed by the 2-D inversion, however, the anomaly can still reflect the true shape and the center position of the ore-body in the main. When the ore-body has certain lengths in strike, the effect of 2-D inversion is good to it, no matter its resistivity is high or low.
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Key words:
- DC resistivity sounding /
- 2-D inversion /
- 3-D model /
- approximate interpretation
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图 2 模型1的平面图(a)及剖面图(b)
Fig. 2. The x-y plane view (a) and the x-z cross section view (b) of the model 1
图 3 模型2和模型3的平面图(a)及剖面图(b)
(a) 围岩电阻率ρ0=50 Ω·m, 矿体电阻率ρ1=100 Ω·m; (b) 围岩电阻率ρ0=100 Ω·m, 矿体电阻率ρ1=50 Ω·m
Fig. 3. Plane views (a) and section views (b) of the model 2 and model 3
图 4 模型1偶极—偶极测深反演断面等值线(等值线单位Ω·m)
Fig. 4. Cross section contours of pole-pole sounding inversion for the model 1
图 5 模型1偶极—偶极测深反演平面等值线(等值线单位Ω·m)
Fig. 5. Horizontal section contours of pole-pole sounding inversion for the model 1
图 6 不同延深的高阻矿体主剖面视电阻率反演断面等值线(等值线单位Ω·m)
a.矿体体积4 m×10 m×4 m; b.矿体体积4 m×8 m×4 m; c.矿体体积4 m×6 m×4 m; d.矿体体积4 m×4 m×4 m
Fig. 6. Contours of apparent resistivity inversion in main profiles of high resistivity ore-bodies with different strike lengths
图 7 不同延深的低阻矿体主剖面视电阻率反演断面等值线(等值线单位Ω·m)
a.矿体体积4 m×4 m×4 m; b.矿体体积4 m×6 m×4 m; c.矿体体积4 m×8 m×4 m; d.矿体体积4 m×10 m×4 m
Fig. 7. Contours of apparent resistivity inversion in main profiles of low resistivity ore-bodies with different strike lengths
表 1 有限单元网格间距
Table 1. Mesh intervals of finite element
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[1] Dabas M, Tabbagh A, Tabbagh J. 3-D inversion in subsurface electrical surveying-Ⅰ Theory[J]. Geophys J Internat, 1994, 119: 975-990. doi: 10.1111/j.1365-246X.1994.tb04029.x [2] Ellis R G, ldenburg D W. The pole-pole 3-D Dc-resistivity inverse problem: a conjugate-gradient approach[J]. Geophys J Internat, 1994, 119: 111-119. [3] Li Y, Oldenburg D W. Inversion of 3-D Dc resistivity data using an approximate inverse mapping[J]. Geophys J Internat, 1994, 116: 527-537. doi: 10.1111/j.1365-246X.1994.tb03277.x [4] Sasaki Y. 3-D resistivity inversion using finite element method[J]. Geophysics, 1994, 59: 1839-1848. doi: 10.1190/1.1443571 [5] Gregory A N, David L A. Three-dimensional magnetotelluric inversion using non-linear conjugate gradients[J]. Geophys J Internat, 2000, 140: 410-424. doi: 10.1046/j.1365-246x.2000.00007.x [6] Beard L P, Morgan F D. Assessment of 2-D resistivity structures using 1-D inversion[J]. Geophysics, 1991, 56(6): 874-883. doi: 10.1190/1.1443106 [7] 阮百尧. 大地电磁测深中用一维反演结果近似二维地电断面的效果[J]. 石油地球物理勘探, 1997, 32(4): 589-595. https://www.cnki.com.cn/Article/CJFDTOTAL-SYDQ199704015.htmRUAN B Y. Effect of approximating 2-D geoelectric fault plane by using 1-D inversion result in magnetotelluric sounding[J]. Oil Geophysical Prospecting, 1997, 32(4): 589-595. https://www.cnki.com.cn/Article/CJFDTOTAL-SYDQ199704015.htm [8] 阮百尧, 熊彬, 徐世浙. 三维地电断面电阻率测深有限元数值模拟[J]. 地球科学——中国地质大学学报, 2001, 26(1): 73-77. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200101013.htmRUAN B Y, XIONG B, XU S Z. Finite element method for modeling resistivity sounding on 3-D geoelectric section [J]. Earth Science— Journal of China University of Geosciences, 2001, 26(1): 73-77. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX200101013.htm [9] 阮百尧, 熊彬. 电导率连续变化三维电阻率测深有限元模拟[J]. 地球物理学报, 2002, 45(1): 131-138. doi: 10.3321/j.issn:0001-5733.2002.01.016RUAN B Y, XIONG B. A finite element modeling of 3-dimensional resistivity sounding with continuous conductivity [J]. Chinese J Geophys, 2002, 45(1): 131-138. doi: 10.3321/j.issn:0001-5733.2002.01.016 [10] 阮百尧, 村上裕, 徐世浙. 激发极化数据的最小二乘二维反演方法[J]. 地球科学——中国地质大学学报, 1999, 24(6): 619-624. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX199906012.htmRUAN B Y, Yutaka M, XU S Z. Least square 2-D inversion method for induced polarization data[J]. Earth Science—Journal of China University of Geosciences, 1999, 24(6): 619-624. https://www.cnki.com.cn/Article/CJFDTOTAL-DQKX199906012.htm [11] 阮百尧, 村上裕, 徐世浙. 电阻率/激发极化率数据的二维反演程序[J]. 物探化探计算技术, 1999, 21(2): 116-125. https://www.cnki.com.cn/Article/CJFDTOTAL-WTHT902.001.htmRUAN B Y, Yutaka M, XU S Z. 2-D inversion programs of induced polarization data[J]. Computing Techniques for Geophysical and Geochemical Exploration, 1999, 21(2): 116-125. https://www.cnki.com.cn/Article/CJFDTOTAL-WTHT902.001.htm [12] Sasaki Y. Automatic interpretation of induced polarization data over two-dimensional structures[J]. Memoirs of the Faculty of Engineering, Kyushu University, 1982, 42: 59-74. -
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