TEM探测深部煤层上覆多电性层的OCCAM反演
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摘要
瞬变电磁法(TEM)以其对低阻体反映灵敏而被广泛用于煤矿水文地质勘探中,当煤层埋藏较深,上覆地层纵向上有多种电性层存在时,瞬变电磁法晚期经验公式计算结果已不能反映实际情况。通过深入研究OCCAM反演算法,认为选择使误差目标函数达到最小的正则化参数,在反演迭代步长过大时进行压缩迭代步长的控制方法,以及最光滑的模型约束,可以提高反演分辨率。在瞬变电磁数据处理中使用加入了上述参数、控制和约束的反演技术,经对理论模型数据进行反演,反演结果与模型的电性分布规律吻合,表明算法正确;在华北煤田深部采场的瞬变电磁法探测应用中,OCCAM反演分辨出了煤层上覆多种电性地层,效果较好。
The transient electromagnetic method is widely used in hydrogeological exploration of coal mine due to its sensitivity to low resistance, when the coal seam is buried deeply and there are various electrical layers on the upper strata, the calculation results of TEM do not reflect the actual geological conditions. We research into OCCAM inversion, that makes the error objective function achieve the minimum of the regularization parameter, the iteration step size control method of compression during the iteration step size is too large, and the smooth model can improve the resolution of inversion. The inversion techniques of regularization parameter selection, optimal step size and constraint model are used in transient electromagnetic data processing. The theoretical model data is inverted, and the inversion result is consistent with the electric distribution of the model, it shows that the algorithm is correct. The application of TEM in deep coalfields in North China showed that OCCAM inversion is able to distinguish the various electrical strata above coal beds, and the result is good.
The transient electromagnetic method is widely used in hydrogeological exploration of coal mine due to its sensitivity to low resistance, when the coal seam is buried deeply and there are various electrical layers on the upper strata, the calculation results of TEM do not reflect the actual geological conditions. We research into OCCAM inversion, that makes the error objective function achieve the minimum of the regularization parameter, the iteration step size control method of compression during the iteration step size is too large, and the smooth model can improve the resolution of inversion. The inversion techniques of regularization parameter selection, optimal step size and constraint model are used in transient electromagnetic data processing. The theoretical model data is inverted, and the inversion result is consistent with the electric distribution of the model, it shows that the algorithm is correct. The application of TEM in deep coalfields in North China showed that OCCAM inversion is able to distinguish the various electrical strata above coal beds, and the result is good.
引文
[1]闫述,薛国强,陈明生.大回线源瞬变电磁法响应理论研究回顾及展望[J].地球物理学进展,2011,26(3):941-947.YAN Shu,XUE Guoqiang,CHEN Mingsheng.Review and perspective of theoretical study on large-loop TEM response[J].Progress in Geophysics,2011,26(3):941-947.
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[9]强建科,李永兴,龙剑波.航空瞬变电磁数据一维Occam反演[J].物探化探计算技术,2013,35(5):501-505.QIANG Jianke,LI Yongxing,LONG Jianbo.1-D Occam inversion method for airborne transient electromagnetic data[J].Computing Techniques for Geophysical and Geochemical Exploration,2013,35(5):501-505.
[10]高阳.瞬变电磁法矩形框发射源一维正反演研究[D].成都:成都理工大学,2014:46-54.
[11]石显新.瞬变电磁法勘探中的低阻屏蔽层问题研究[D].北京:煤炭科学研究总院,2005.
[12]俞黎明.国外瞬变电磁法中正反演问题研究现状[J].地质科技情报,1987,6(4):115-119.YU Liming.Research status of forward and inverse problems in transient electromagnetic method[J].Geological Science and Technology Information,1987,6(4):115-119.
[13]GROOT-HEDLIN De C,CONSTABLE S C.Occam’s inversion to generate smooth two-dimensional models from magnetotelluric data[J].Geophysics,1990,55(12):1613-1624.
[2]刘最亮,王鹤宇.大定源瞬变电磁法在含水断层构造探测中的应用[J].煤田地质与勘探,2012,40(5):67-70.LIU Zuiliang,WANG Heyu.Application of transient electromagnetic method in the detection of water-bearing fault structure[J].Coal Geology&Exploration,2012,40(5):67-70.
[3]李刚,潘和平,王智,等.回线源瞬变电磁法一维反演算法[J].煤田地质与勘探,2017,45(5):161-166.LI Gang,PAN Heping,WANG Zhi,et al.One-dimensional inversion for loop source transient electromagnetic method[J].Coal Geology&Exploration,2017,45(5):161-166.
[4]刘英.浅析瞬变电磁法不同回线装置的优缺点[J].物探装备,2009,19(5):325-327.LIU Ying.The advantages and disadvantages comparison among TEM different loops[J].Equipment for Geophysical Prospecting,2009,19(5):325-327.
[5]李貅.瞬变电磁测深的理论与应用[M].西安:陕西科学技术出版社,2002.
[6]KAUFMAN A A,KELLER G V.频率域和时间域电磁测深[M].王建谋,译,北京:地质出版社,1987.
[7]CONSTABLE S C,PARKER R L,CONSTABLE C G.Occam’s inversion:A practical algorithm for generating smooth models from EM sounding data[J].Geophysics,1987,52(1):289-300.
[8]马炳镇.TEM一维反演技术在老窑水勘查中的应用[J].煤田地质与勘探,2018,46(1):148-153.MA Bingzhen.Application of one-dimensional TEM inversion technology in gob water exploration[J].Coal Geology&Exploration,2017,46(1):148-153.
[9]强建科,李永兴,龙剑波.航空瞬变电磁数据一维Occam反演[J].物探化探计算技术,2013,35(5):501-505.QIANG Jianke,LI Yongxing,LONG Jianbo.1-D Occam inversion method for airborne transient electromagnetic data[J].Computing Techniques for Geophysical and Geochemical Exploration,2013,35(5):501-505.
[10]高阳.瞬变电磁法矩形框发射源一维正反演研究[D].成都:成都理工大学,2014:46-54.
[11]石显新.瞬变电磁法勘探中的低阻屏蔽层问题研究[D].北京:煤炭科学研究总院,2005.
[12]俞黎明.国外瞬变电磁法中正反演问题研究现状[J].地质科技情报,1987,6(4):115-119.YU Liming.Research status of forward and inverse problems in transient electromagnetic method[J].Geological Science and Technology Information,1987,6(4):115-119.
[13]GROOT-HEDLIN De C,CONSTABLE S C.Occam’s inversion to generate smooth two-dimensional models from magnetotelluric data[J].Geophysics,1990,55(12):1613-1624.