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探测孤石高阻体的跨孔电阻率CT水槽物理模拟实验研究 总被引：1，自引：0，他引：1
采用重庆奔腾数控技术研究所的WDJD-3型多功能数字直流激电仪,在电法实验室水槽内布设了探测孤石高阻体的跨孔电阻率CT法观测系统,进行了物理模型实验。物理模拟实验采用多种观测装置(二极、三极和四极装置),对采集到的数据进行反演成像,得到如下结论:①二极装置电阻率CT反演成像结果不能反映出高阻体的位置与大小;②三极装置CT反演成像结果能较好反映孤石高阻体的位置与大小;③四极装置电阻率CT反演成像也能反映出孤石高阻体的位置与规模,效果与三极装置基本相同。物理模拟实验结果表明:三极或四极装置的跨孔电阻率CT法可用于探测高阻体,它具有采集方式灵活、数据稳定可靠、成像结果直观清晰的优点。基于物理模拟实验的结果,采用电阻率CT法对地铁盾构隧道洞身范围内的孤石高阻体探测具有一定的指导意义。对孤石体的三维电阻率CT法物理模拟实验正在进一步研究中。 相似文献
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为提高高密度电阻率法的探测精度和效果,在常德市鼎城开发区开展了基于比照印证已有地质钻孔数据进行约束模型的一维到二维的逐级反演试验.文中首先阐述了一维层状模型的正反演解析解的计算方法,并完成了高密度电阻率法二维模型的正演响应公式和基于高斯牛顿法的反演理论推导;其次设计层状模型利用有限单元法进行了正演模拟,从其响应数据中抽取了单点测深数据进行层状反演,并利用一维反演结果结合已有地层电阻率信息构建了二维初始模型进行反演,实现了高密度电阻率法逐级反演的理论研究;最后,选取常德市鼎城区跨越常德—益阳区域构造的高密度电法剖面进行试验,并根据地质情况和钻孔信息对野外采集的连续剖面的每个测点的数据进行了层状划分,构建二维模型对其进行反演,完成了高密度电阻率法逐级反演的应用研究.结果表明:在城市开发区利用逐级反演的思想对高密度电阻率法探测数据进行处理,有助于提高反演精度和地质解释的准确度. 相似文献
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利用高密度电阻率法确定滑坡面的正演研究 总被引：2，自引：0，他引：2
高密度电法探测是滑坡面探测的有效手段,适宜 的现场工作方案和相应的资料解译模型,是获取 可靠探测成果的前提。本文针对高密度电法勘探 中常用的四类电极排列方式,即维纳、施伦贝谢、 偶极、二极,利用有限元的方法二维正演模拟建 立了均质土坡滑面、软弱夹层滑面、堆积层滑面、 构造破碎带滑面的标准地电模型剖面;明确了进 行不同类型滑坡工程地质调查时不同电测装置的 探测能力和视电阻率异常模式;提出复杂地质条 件下斜坡问题探测数据有效处理的设计比值参数 方法。最后给出若干利用高密度电阻率法进行滑 坡工程地质调查的典型实例。 相似文献
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电成像、电测深、电剖面法是目前3种最基本的电阻率探测技术.三维探测的观测系统主要有地表和钻井-地表这两种不同类型的测量.前者的电极阵列成矩形网格状,多采用单极-单极观测装置以增大探测深度,技术难点在于远电极的设置往往会带来难以消除的地电噪音,限制了单点电位测量的精度和应用范围;后者在油田生产的中后期的分层注水以及核废物注浆处理过程中,需要确定流体或者浆片的运移与分布,取深钻井的钢套管作为一个供电电极,形成垂直线电流源,再以钻井为中心对地表的环状网格进行二极或三极测量.可以取得视电阻率和自电位两种测量,得到三维电阻率和异常电荷概率分布的图像. 相似文献
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电阻率层析成像是根据阵列电极的电位测量重建电阻率图象的一种新技术，与波动CT问题有着本质的不同，图象重建的关键在于快速完成对稳定电流场的泊松方程求解和反演迭代．本文以岛裕雅的级联算法为例，简介了数学方法的基本步骤．针对山东汶南煤矿的矿井涌水问题，实施了地表层析探测，3条剖面总长5 832 m，最大成像深度120 m．层析图象清晰地揭示了地层结构、煤矿采空区、破碎带和裂隙(或管道状)漏水区的分布．所得结果经钻孔检验正确，已成功地应用于继而展开的堵漏截流治水工程．文中针对技术方法和存在的问题进行了讨论． 相似文献
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综合地球物理技术在采空区的探测中发挥了重要作用.目前通常采用单方法反演、仅对不同方法反演结果进行对比解释的综合勘探方式,单方法反演的多解性严重降低了其探测精度.如何提高采空区的探测精度,对采空区进行有效探测一直被认为是地球物理技术面临的首要难题.为了提高地震与电法技术的探测精度,基于交叉梯度联合反演理论,设计了地震初至折射走时数据和高密度电法数据的联合反演算法流程,对采空区理论模型和野外实际数据进行了联合反演处理.结果发现通过两者的联合反演,不仅可以提高采空区电阻率反演模型的成像效果,而且能够获得地震单方法反演难以成像的采空区低速异常体,从而提高了地震与电法技术对采空区的探测精度.表明地震与电法探测数据联合反演是一种提高采空区探测精度的有效方法. 相似文献
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直流电阻率法以其对含水构造响应敏感且适应性强的特点,是隧道施工期超前地质预报的常用方法.针对目前定点源三极观测方式易受到测线附近旁侧异常干扰与聚焦观测方式探测距离过短无法三维成像的问题,提出了一种基于多同性源阵列电阻率的隧道超前探测新方法,利用环形布置的多同性源供电压制隧道掌子面后方的异常体的干扰,同时增强掌子面前方远处异常体的敏感度,阵列电极测量可为含水构造的三维反演成像提供三维数据.首先,开展了含水构造超前探测的数值正演模拟,发现多同性源方法的视电阻率纵向微分曲线极小值以及与横轴的交点位置可对异常体位置进行定性判断,探讨了多同性源方法对后方及侧向异常干扰的响应特征及识别方法.其次,将电阻率光滑约束与轨迹光滑策略引入蚁群反演算法,提出了一种最小二乘方法与改进蚁群算法相结合的混合反演算法,反演数值算例表明混合反演算法能够实现含水构造的三维成像,较好地反演出不同距离的含水构造位置,并使其边界较为清晰.为了验证多同性源探测方法的探测效果开展了物理模型试验,多同性源阵列电阻率法能较好的反映含水构造的存在,与实际含水构造的位置较为相符. 相似文献
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为研究电测井和油气层的关系,根据电场理论,将砂岩电导率定义为地层水电导率、含量、相对电场强度的积.提出电介质颗粒面电荷与电偶极子等效的认识,进一步得出砂岩的电场方程.解砂岩电场方程得出相对电场强度表达式,将其带入砂岩电导率定义得电测井和油气层关系的一个理论公式,并用实验资料验证了公式的有效性. 相似文献
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In this article, the phenomenon of generation of corona discharges on the tops of trees and plants is described. In the first part of the text, the conditions for generation of this electric field which leads to formation of corona discharge and transfer of electric charge between atmosphere and Earth, are discussed. Experimental results of the onset voltage and its dependence on the discharge parameters are presented. The coincidence between released species from corona burning point and surrounding atmosphere is also discussed. Equation for the calculation of critical intensity of the electric field and onset voltage in dependence on radius of the tip are also discussed and compared with experimental data and equations for current–voltage characteristics are described. The attempt to explain differences between theory and measured data is proposed. 相似文献
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Significant changes of electrical resistivity of saturated rocks and water pressure along sliding surface occurred during stick-slips in our direct shear experiment. Two types of changes of electrical resistivity occurred. In the first, resistivity decreased with increasing shear stress, reached minimum together with a sudden release of shear stress and returned to a higher value immediately afterwards. In the second, resistivity again decreased with increasing stress but, in contrast to the first type of changes, it decreased further upon the sudden drop of shear stress. The magnitude and the direction of the changes of water pressure on the sliding surface during stick-slip were not uniform, indicating local variations of surface deformation. 相似文献
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Measurement of the electric field data due to an inductive loop source in a controlled source electromagnetic survey is not common, because electric field data, usually involving grounded electrodes, are expensive to acquire and difficult to interpret. With the recently developed capability of versatile three‐dimensional inversion, we revisit the idea of measuring electric field in a large ground loop survey for mineral exploration. The three‐dimensional modelling and inversion approach helps us quantitatively understand the detectability and recoverability of the proposed survey configuration. Our detectability study using forward modelling shows that the relative anomaly (percentage difference) in electric field does not decay with a lower induction number, but the conventional magnetic field data (dB/dt) does. Our recoverability study examines how much and what kind of information can be extracted from electric field data for the reconstruction of a three‐dimensional model. Synthetic inversions show the following observations. (i) Electric field data are good at locating lateral discontinuity, whereas dB/dt has better depth resolution. (ii) Electric field is less sensitive to the background conductivity and, thus, is prone to misinterpretation because of a bad initial model in inversion. We recommend warm‐starting the electric field inversion with an initial model from a separate dB/dt inversion. (iii) Electric field data may be severely contaminated by near‐surface heterogeneity, but an inversion can recover the deep target concealed by the geologic noise. (iv) Even one line of single‐component electric field data can greatly improve the horizontal resolution in a dB/dt inversion. Finally, we investigate a field dataset of both electric field and dB/dt measurements at a uranium deposit. The field example confirms that the electric field and magnetic field data contain independent information that is crucial in the accurate recovery of subsurface conductivity. Our synthetic and field examples demonstrate the benefit of acquiring electric field data along with magnetic field data in an inductive source survey. 相似文献
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几年以前 ,我国尚未独立开展过海洋电磁探测 ,没有获取海洋岩石层电性资料的技术手段。然而 ,地下岩层的电性参数较之其他物性参数能更好地反映岩石的性质以及岩石所处的物理状态 ,因此迫切需要发展海底大地电磁探测技术。海底大地电磁探测是把仪器布置在海底 ,采集海底大地电磁场数据 ,从而研究海底以下不同深度上介质导电性的分布规律 ,达到了解地下不同深度地质情况的目的。经过两年的努力 ,我们已基本实现了海底大地电磁探测技术的研究目标 相似文献
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根据电法勘探的基本原理．参考已推导出的线对地漏电的基本公式．给出了《地电观测技术规范》允许漏电电流最大值时的电阻率相对误差三维分布图及平面等值线图，并讨论了其分布特征；同时给出了不同位置ρｓ相对变化１．５％时的漏电电流三维分布图及平面等值线图；粗略地给出了外线路绝缘电阻的允许范围，为提高地电台站布设的经济效益提供了较好的理论依据。 相似文献
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For a number of applications in geoscience, electrical conductivity of water is often used as a collective measure of the concentration of dissolved solids. A method for temperature correction of electrical conductivity data based on regression analysis of the actual temperature/conductivity relationship of a number of water samples from natural streams is presented. It is shown that the generally used formulae for temperature correction give corrected results that deviate considerably from the values determined by actual measurements. The error increases with decreasing water temperature and may result in data that deviate by as much as 20 per cent from the true values. The implications are thus especially important for measurements of solute loads and concentrations during periods of low stream water tetaperatures e.g. during snowmelt. 相似文献
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为查明滇西三江构造带及邻区复杂的构造特征,并揭示该区深部电性结构,沿福贡—巧家布设了一条长约410 km的大地电磁剖面.共观测到61个物理点,其中宽频大地电磁测点41个,长周期大地电磁测点20个.通过对采集到的数据进行一系列的处理、反演,得到了沿剖面的壳幔电性结构模型.并结合研究区内区域地质资料及其他地球物理资料,对剖面所经过的各个主要地质构造单元及主要断裂带进行了综合解释.电性结构模型揭示沿剖面地壳电性层次复杂,深部电性结构由西往东呈分块展布,横向变化大,壳内广泛发育低阻异常.在中甸构造带(香格里拉地块)和盐源—永胜构造带深部壳幔存在大规模低阻异常,这可能与地下局部熔融体和地热流有关;康滇构造带壳幔存在大规模高阻异常,表明地壳中曾经有地幔物质侵入;在大凉山构造带地下10~50 km深处存在一呈横向“半月形”展布的低阻体,电阻率值不满10Ωm,结合地质资料与前人的研究成果,推测该低阻体成因应与青藏高原东南缘“地壳管道流”有一定关联. 相似文献
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We report novel laboratory measurements of the full electrical resistivity tensor in reservoir analogue quartzose sandstones with clay contents less than 1.5%. We show that clean, homogeneous, visually uniform sandstone samples typically display between 15% and 25% resistivity anisotropy with minimum resistivity normal to the bedding plane. Thin‐section petrography, analysis of fabric anisotropy, and comparison to finite‐element simulations of grain pack compaction show that the observed anisotropy symmetries and magnitudes can be explained by syn‐depositional and post‐depositional compaction processes. Our findings suggest that: electrical resistivity anisotropy is likely to be present in most clastic rocks as a consequence of ballistic deposition and compaction; compaction may be deduced from measurements of electrical anisotropy; and the anisotropy observed at larger scales in well logging and controlled‐source electromagnetic data, with maximum resistivity normal to bedding, is most likely the result of meso‐scale (10?1 m–101 m) periodic layering of electrically dissimilar lithologies. 相似文献
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用电磁阵列剖面法 (EMAP)、大地电磁测深方法 (MT) ,沿三河 -平谷 8级大震震源区 ,作了 31 8km长的EMAP探测和两条总长 150 0 5km共 36个点的MT探测。获得了研究范围内的地壳上地幔电性结构、高导层特征和陡变带、高导异常体、断裂展布、岩石圈结构等结果 ,为搞清地震危险区的深浅构造关系、从电性结构特征推测发震模式和预测未来强震的可能地点提供了介质电性的多种参数 相似文献