共查询到19条相似文献，搜索用时 203 毫秒
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井地电阻率成像法利用井套管作电流源向井下供入大功率直流电流,在地表测量由地下介质的电性变化形成的电位分布,通过反演可得到地下介质的电阻率分布.针对大斜度井和水平井开展井地三维电阻率数值模拟和反演研究,对油田注水及压裂效果监测具有重要意义.基于井地电阻率成像法原理,采用有限差分法和不完全切勒斯基共轭梯度法进行了三维正演模拟,研究了大斜度井和水平井的井地电位响应特征.提出了采用层状约束阻尼最小二乘法由浅到深地进行大斜度井和水平井的多层联合反演,并对实际水平井井地电位各个层段数据进行了三维反演.模拟结果表明,倾斜线源和水平线源会对地面电位响应产生明显影响,在反演中需要考虑线源形态.实际水平井井地电位反演成像表明,考虑倾斜线源或者水平线源的联合反演得到了准确的水平井三维注水层成像图,得出注水层的真电阻率分布,能够判断注水运移方向. 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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垃圾填埋场渗漏污染三维分布式电学监测系统研制及应用 总被引：1，自引：0，他引：1
垃圾填埋场建设期将电极传感器网状布设于防渗层下方,垃圾场启用后通过预设电极实现观测区自然电位和地下介质电阻率测试.对比不同时期实测自然电位和视电阻率剖面特征变化,确定垃圾场渗漏与否、渗漏点的位置、数量及渗滤液形成羽状体的空间分布和扩散过程.三维分布式电学监测系统就是基于上述理念设计研制的,包括采集站、供电控制器及传感器系统,可同时完成多个位置点电位测量.粉砂层中渗滤液扩散过程的原位三维电学监测结果显示渗滤液污染区呈现自然电位负异常和低阻特征,低阻异常区分布范围和实际污染区具有良好的对应关系,污染区扩散特征可通过分析低阻异常区变化来确定. 相似文献
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成层半空间深埋电极产生的电位分布 总被引：2，自引：1，他引：1
首先给出了点电流源在均匀半空间中所产生电位的解析表达式;其次研究了源电极位于表层和底层时成层半空间介质中的电位分布;最后研究了源电极位于任一层时成层半空间介质中的电位分布. 相似文献
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采用715m埋深的矿井巷道揭露的煤系地层和正断层作为试验对象,由巷道和其侧帮水平钻孔构成相互垂直的二条电法观测线,在断层下盘进行注水,时空域观测二条测线上岩体的地电场响应.试验中动态反演电阻率图像可以跟踪水体渗流运动过程,判定岩体中断层导水性能及其控水作用;自然电位随着岩体内注入水体逼近电极而上升,停止注水而下降,自然电位指示岩体水体渗流的波动规律;激励电流的升降与出水点位置相关,距离出水点越近激励电流上升越明显.试验表明对于受断层控制的深部复杂岩体的水体渗流,可以运用地电场的时空特性进行监测评价.动态地电场监测技术,可用于复杂岩体的导、隔水性能研究. 相似文献
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在坑道超前探测方法中,直流电阻率法原理和操作简单,应用前景广阔,其中侧向聚焦电阻率法应用在测井中已经成为一种常用方法.本文研究了三维坑道直流聚焦法电极组合,首先计算分析了两个同性点电源的电流分布规律,指出由于电流的相互排斥作用,电流密度在这两个点电源的中垂线下一定深度处产生最大值,这个深度与这两个点源之间的距离成正比.基于上述原理,设计出三种电极组合：四点电源、五点电源和九点电源布极方式.其次,用三维有限单元数值模拟的方法计算了上述三种电极系的空间电位分布,得出九点电源方式对电流聚束效果较好,而且当主电极电流小于屏蔽电极电流时效果最好. 相似文献
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The forward and inversion methods of resistivity tomography with a vertical line current source (RTVLCS) were introduced in this paper. The technique was applied to the evaluation of residual oil saturation of the reservoir studied in an old oil region. The observed water saturation during the course of the measurement of RTVLCS and subsequent drilling records proved the reliability of our result. However, our model has not included the influence of all factors such as electrical contact resistance between the metal casing and surrounding rocks and of the size of the metal cased well taken as a vertical line current source (VLCS). In addition, RTVLCS was carried out after the well had been in use for many years, while the initial resistivity values used in the inversion were obtained from the resistivity curve logged upon the completion of the well. Therefore, the residual oil saturation obtained by RTVLCS is relative and has not complete consistency with real situations, and can only be used as reference for adjusting a plan for oil production in the mid- or post-phase of an oilfield. 相似文献
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Controlled‐source electromagnetic monitoring of reservoir oil saturation using a novel borehole‐to‐surface configuration 
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下载免费PDF全文 To advance and optimize secondary and tertiary oil recovery techniques, it is essential to know the areal propagation and distribution of the injected fluids in the subsurface. We investigate the applicability of controlled‐source electromagnetic methods to monitor fluid movements in a German oilfield (Bockstedt, onshore Northwest Germany) as injected brines (highly saline formation water) have much lower electrical resistivity than the oil within the reservoir. The main focus of this study is on controlled‐source electromagnetic simulations to test the sensitivity of various source–receiver configurations. The background model for the simulations is based on two‐dimensional inversion of magnetotelluric data gathered across the oil field and calibrated with resistivity logs. Three‐dimensional modelling results suggest that controlled‐source electromagnetic methods are sensitive to resistivity changes at reservoir depths, but the effect is difficult to resolve with surface measurements only. Resolution increases significantly if sensors or transmitters can be placed in observation wells closer to the reservoir. In particular, observation of the vertical electric field component in shallow boreholes and/or use of source configurations consisting of combinations of vertical and horizontal dipoles are promising. Preliminary results from a borehole‐to‐surface controlled‐source electromagnetic field survey carried out in spring 2014 are in good agreement with the modelling studies. 相似文献
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We calculate three-dimensional sensitivity coefficients distribution of apparent resistivity observation when Schlumberger array is used by using finite element method. Analysis results suggest that for the situation of one-dimensional positive or minus coefficient of surface medium, three-dimensional sensitivity coefficients distribution at surface shows similar patterns, and sensitivity coefficients distributions of different layered electric structures are also similar. There are two approximate ellipses at the two-dimensional surface plane between current electrodes and potential electrodes, where sensitivity coefficients are minus, and sensitivity coefficients at other areas are positive. Sensitivity coefficients at two approximate ellipses between current electrodes and potential electrodes are minus at the vertical section along monitoring line, while others are positive. From the three-dimensional view, minus sensitivity coefficients are at the two approximate half ellipsoids between current electrodes and potential electrodes when arrays are applied at surface. And coefficients near the electrodes are much greater than other areas. When resistivity of local areas at surface changes, we can qualitatively analyze the disturbing effects caused by the areas using three dimensional sensitivity coefficients distribution, and the analysis result can serve as reference for further experiment and numerical model quantitative analysis. 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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Ahmad Neyamadpour Samsudin Taib W. A. T. Wan Abdullah 《Studia Geophysica et Geodaetica》2009,53(3):389-402
A 3D electrical resistivity imaging survey is presented in this paper. The objective was to investigate an underground wastewater
system at the University of Malaya, Malaysia. Apparent resistivity data were collected along ten parallel lines using a Wenner-Schlumberger
configuration; electrode cables were oriented in the x-direction with 3 m spacing. Roll-along measurements using a line spacing
of 3 m were carried out covering a grid of 20 × 10 electrodes. All data sets were merged into a single data file in order
to perform a 3D inversion. Two different 3D least squares algorithms, based on the robust inversion method and the smoothness-constrained
technique, were used for the inversion of the apparent resistivity data. Both the horizontal and vertical extents of the anomalous
zones found by inversion are displayed. The results indicate the superiority of the robust inversion method over the smoothness-constrained
technique at this site. The results are in sufficient accordance with previously known information about the investigation
area. The results show that 3D electrical resistivity imaging surveys, in combination with an appropriate 3D inversion method,
can be highly useful for engineering and archaeological investigations as well as for environmental applications. 相似文献
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为研究地层电性变化时不同区域对电磁波测井响应的贡献分布,从响应信号对地层参数求偏导的角度,给出一种新的电阻率敏感性函数定义,引入模式匹配法对纵向成层、径向非均匀介质敏感性分布进行快速模拟;通过对敏感性函数纵、横向积分给出了单发双收线圈系纵、横向探测范围,研究了井眼、频率、背景地层电阻率等对探测特性的影响.结果表明:敏感性函数能够定量表征响应对地层纵向与径向微观与宏观敏感性,幅度比与相位差敏感性分布形态类似,幅度比较广较深,而相位差分辨率高,敏感范围小;敏感性函数进行径向积分后可表征仪器的探测深度,与伪几何因子对比达到了同样的效果;背景地层电阻率在1~100Ωm变化时,工作频率2 MHz下幅度比探测深度约为0.6~2.3m,相位差为0.3~0.8m,幅度比50%纵向积分敏感性层厚约为0.3~1.6m,相位差约为0.2~0.6m;异常体与背景地层电阻率对比度在1~50变化时,引起的探测深度与敏感性层厚差异约为0.1~0.2m,远小于地层电阻率的影响. 相似文献
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Anisotropy of the apparent resistivity variation rate near the epicentral region for strong earthquakes 总被引：1，自引：0，他引：1
IntroductionThe geo-electrical anisotropy before earthquake is of special significance for the prediction of earthquake location and for the research on crustal stress status near the epicentral region. The anisotropy has been studied from various aspects (CHEN, et al, 1983; QIAN, et al, 1985, 1996; LU, et al, 1990a; MAO, et al, 1995; RUAN, et al, 1999). But the anisotropic phenomena presented by geo-electrical data are not practically satisfactory and not clear as compared with the res… 相似文献