露天煤矿地下水电磁探测与类型判别

为准确确定露天煤矿地下水分布与类型,根据不同赋存条件电磁差异,基于磁场强度与电阻率参数进行异常划分与类型判别。以新疆某露天煤矿为例,采用高精度磁法通过磁异常强度确定烧变岩边界,并采用高密度电法和瞬变电磁法通过电阻率圈定低阻异常区,结合异常响应差异分别推断地下水分布范围与赋存类型。地面钻探验证探测成果的准确性。结果表明:露天煤矿烧变岩水与砂岩裂隙水电磁响应差异明显,基于磁场强度与电阻率的双参数综合电磁法能准确圈定其分布范围,并判别其赋存类型。     

基于数字岩心的岩石电性微观数值模拟(英文)

本文利用x射线CT获取反映岩心微观结构的三维数字岩心,利用数学形态学中的开运算模拟了岩石的油驱水排驱过程中,不同含水饱和度下油和地层水在孔隙空间中的分布。利用有限元方法计算了岩石电阻率,进而得到岩石地层因素和电阻率指数,并考查了岩石润湿性对岩石电阻率指数的影响。数值模拟结果表明：基于数字岩心的水湿岩石地层因素和电阻率指数数值模拟结果与实验结果一致,拓展了岩石电阻率实验的能力;岩石润湿性对岩石电性有重要影响,在相同含水饱和度下,油湿岩石电阻率高于水湿岩石电阻率,油湿岩石饱和度指数远大于水湿岩石饱和度指数。     

过套管地层电阻率曲线环境影响校正方法研究

过套管电阻率测井是在金属套管井中测量地层电阻率的一种电法测井技术,其测量结果受套管、层厚/围岩、水泥环等井眼环境因素的影响,所以在进行过套管电阻率测井资料解释时必须进行测井环境影响因素校正.本文在论述过套管电阻率测井原理的基础上,针对大庆油田引进的俄罗斯过套管电阻率测井仪器ECOS,分别考察了层厚/围岩、水泥环对测量结果的响应规律,利用正演模拟方法研制完成了层厚/围岩影响校正图版以及水泥环影响校正图版.在计算机上实现了层厚/围岩、水泥环影响校正的算法,并利用模型算例和测井实例验证了本文方法的合理性.该方法能够减少水泥环的影响,提高层厚小于1.0 m薄层电阻率的测量精度,为过套管电阻率测井资料正确解释提供了保障.     

高密度电阻率法在海底金矿含水构造探测中的应用

海底金矿上覆岩层中含水直接对矿床的开采构成威胁,选择山东三山岛金矿新立矿区海底-135m水平沿脉巷道,采用地球物理高密度电阻率法对该巷道635m测线以下200m深度范围内岩体中的含水构造进行了坑道探测,利用三种装置(温纳装置(Wenner)、偶极装置(Dipole-Dipole)、Schlumberger装置)进行实施,相互验证,取得了很好的探测结果.温纳、偶极和Schlumberger三种装置的视电阻率反演结果反映在测线(-135m沿脉巷道)以下至30m深度为一高阻层,表明自-135~-165m的岩体中已不含水或含少量的水;测线以下30~60m段为低阻层,反映-165~-200m的岩体中含基岩裂隙水;测线以下大于60m的地段为特高阻层,反映-200m以下岩体含水性逐渐变差.该探测结果与矿区水文地质结构调查分析结论具有很好的一致性,表明了坑道高密度电阻率法探测含水构造是可行的.     

Electric potential and apparent resistivity in rocks containing non-uniformly distributed cracks

IntroductionIn multidisciplinary research of earthquake predication, the geoelectric method is one of the important branches. It takes the electric phenomenon or the electric property changing of the earth medium in seismogenic process as the studying objects, and it is the important composing portion of the earthquake-development comprehensive research. The electric parameters of the earth medium, mostly the resistivity, are the main body in geoelectric research.Experiments indicate (LU, et …     

岩石裂隙电阻率特征研究

岩石的电阻率差是电阻率法的物理前提,利用电阻率法研究断层是比较有效的方法。利用断层破碎带与周围岩石的电阻率差异,跨断层做了大量的实验数据,通过对比和分析,得出了研究破碎带与周围岩石的电性差异,寻找变化规律,研究其变化特征。对今后断层探测具有重要价值,对防震减灾具有重要意义。     

饱水和排水过程中岩石电阻率各向异性特征的电阻率成像法研究

从电阻率的角度研究岩石裂隙介质的各向异性特征是一种方便而有效的方法,但多限于空间单个点上的测量数据分析.通过在砂岩岩样上的饱水与排水实验以及同步进行的高密度电阻率成像监测,探讨了应用高密度电阻率成像法获得图像研究岩石各向异性特征的可能性,分析了饱水与排水过程中岩石电阻率在不同方向上的响应特性.结果表明,电阻率成像法在分析岩石裂隙介质的各向异性方面具有多方向成像和动态监测的优点,可以通过对不同方向上获得的电阻率图像的分析,提取出岩石沉积结构的空间分布模式,清晰地反映出岩石在饱水和排水过程中电阻率变化空间分布模式的各向异性特征.     

Experimental research on the rock electrical parameter dispersion properties in the displacement process

Based on experiments on rock electrical parameter dispersion properties in both water displacing oil and oil displacing water processes, it is found that the frequency dispersion properties of electrical parameters in water-bearing rocks are quite different from those in oil-bearing rocks. Oil saturation can severely impact the rock electrical parameter dispersion properties and as the oil saturation increases, the properties are more distinguishing. The variation of formation water salinity has a significant effect on the rock resistivity, hence the modulus of the rock complex resistivity varies with water saturation and a U-shaped curve occurs over a single frequency, just like the normal resistivity. However, the effect of formation water salinity on the rock frequency dispersion is less than that of oil saturation. As a result, the rock electrical parameter dispersion properties will have a significant potential of application in the evaluation of watered-out zones as well as identification of oil-bearing zones and water-bearing zones.     

时频电磁技术及其在中国西部地区的应用

The time-frequency electromagnetic （TFEM） method combines frequency-domain sounding with time-domain sounding to form a comprehensive system so that it is possible to select different frequencies and induce waves according to the objective depth to be explored. During processing not only resistivity but also polarization information can be provided so we can study resistivity as well as predict oil-bearing characteristics simultaneously. Timedomain resistivity information is obtained by pseudo-2D resistivity inversion and frequencydomain IP information is obtained using the Cole-Cole model. Some successful applications in western China show that it provides unique results in an overthrust zone, deep igneous rock investigation, and hydrocarbon prediction.     

电场差分法理论研究

对均匀大地和二层大地的频率域电场差分法理论曲线进行的计算和研究表明,电场差分法是一种以目标地质体和围岩在电阻率和极化率方面的差异为基础,根据测量到的能明显反映激电响应与电磁耦合响应的比值随频率变化的P参数曲线在性态上的差异来圈划油气藏的一种电法勘探方法. 因为它圈划油气藏的物理基础是油气藏上方与围岩上方测量到的电磁耦合响应和激电响应的差异,所以在圈划油气藏方面,该方法与复电阻率法类似,同样具有找油气的优良性能. 此外,该方法与复电阻率法相比,具有对目标地质体和围岩的电阻率和极化率差异反映灵敏、效率高、成本低等优点,所以它是一种值得推广的找油气的电法勘探方法.     

New Methods for Modeling Laterolog Resistivity Corrections

The paper presents methods for laterolog response modeling. In Coulomb’s charges method, Laplace’s equation is solved for the electric field distribution in rock medium with internal boundaries between different resistivity layers. There, the boundary problem is reduced to Fred-holm integral equation of the second kind. The second method uses a finite element array to model apparent resistivity from laterolog. The task is treated as DC problem and the Laplace equation is solved numerically. The presented methods were applied to borehole data covering a typical stratigraphie section of the Fore-Sudetic Monocline in southwestern Poland. Apparent resistivity was calculated using the Coulomb’s charges method and alternatively modeled using a finite element method which gave similar results. Then, a series of linear corrections for borehole, shoulder bed, and filtration effects for apparent resistivity obtained by the Coulomb’s charges method demonstrated the feasibility of calculating true resistivity of virgin and invaded zones. The proposed methods provide a flexible solution in modeling which can be adapted to other logs.     

1.2千巴围压下岩样破裂和摩擦滑动过程中电阻率变化h

在1.2千巴围压下进行了三种初始饱和岩样(辉长岩、花岗岩Ⅰ和Ⅱ,各以淡水和盐水饱和)的压缩实验直至破裂并继续到摩擦滑动,所有实验中测定了岩样电阻率。 以Brace等人研究表面电导的方法为基础,我们引入给定含水岩样的体电阻系数和面电导系数两个专用术语以分析实验结果。发现一旦岩样开始膨胀,其面电导系数随差应力增加都增大。结果表明:含水岩样体膨胀后电阻率下降主要是由于表面电导作用的增强。 和前人的结果不同,不同岩样摩擦滑动时电阻率变化各异。作者提出:这种差异可能与岩石中所含矿物颗粒大小有关。含大颗粒的岩石滑动时电阻率下降,而含小颗粒的岩石滑动时电阻率上升。      

裂隙非均匀分布岩石中的电位及视电阻率计算

计算了在均匀高阻介质中含有低阻裂隙的岩石的电场分布，并由此推导出裂隙非均匀分布的岩石中视电阻率的计算公式．结果表明，裂隙的埋深、规模、走向（平行或垂直视电阻率测线）以及真电阻率等，对视电阻率的观测和计算结果都有不同程度的影响．本文结果对视电阻率法用于地震分析预报提供了一种有效的计算方法．      

视电阻率法测矿井岩石应变实验的初步总结

本实验目的是揭示受力岩石中应力与电阻率的关系,以验证形变电阻率法能否用于地震预报工作。 实验在一离地面深100多米、正在开采的矿坑中进行。视电阻率的测量用四极对称装置,干电池供电,最高电压13.5伏,最大观测均方误差为1-2％。五个测点上贴了电阻丝应变片,以测定岩石主应变的大小、方向以与视电阻率极大值进行对比。应变计的读数值最大误差不超过3-4με。实验中考虑了岩石有严重极化现象的影响。 实验的初步结果表明:岩石的视电阻率和应变值的变化,总趋势相当一致,所以用形变电阻率法来测量应变是极有希望的。对1973年在四川省南坪发生的几次地震进行震例分析的结果,得到同样的结论。 文中对实验中存在的问题,也作了一些讨论。     

地电阻率与水位关系的机理分析

从地电阻率的观测理论出发, 指出地电阻率场地的电性结构、 岩石的饱和度和孔隙度决定了地电阻率和水位的关系。 在长期的观测资料基础上, 通过实例系统地分析了地电阻率和水位的关系, 给出了不同层位的水位变化和不同方式的水位变化对地电阻率观测结果的影响, 认为非构造水位变化与地电阻率的关系主要取决于表层土壤或岩石的水饱和度, 构造水位变化与地电阻率变化存在明确的相关关系, 从而进一步探讨了与前兆异常有关的水位和地电阻率变化。     

不同矿化度下泥质对岩石电性影响的逾渗网络研究

为了进一步认识泥质对岩石宏观电性的影响规律,本文利用非规整三维逾渗网络模型,通过数值模拟研究了不同矿化度下泥质对岩石电性影响的规律. 模拟结果表明：在中低矿化度下,泥质对岩石导电整体上呈现减阻作用,随着泥质含量的增加,电阻率降低的速度减慢;中等矿化度下泥质的减阻效果明显弱于低矿化度下的减阻效果;在高矿化度下泥质对岩石导电整体上呈现增阻作用. 在高矿化度、高含水饱和度下泥质对岩石电性的影响较小. 泥质起减阻、增阻作用的具体矿化度范围取决于储层的孔隙度、连通性以及地层温度等特性.     

2D cooperative inversion of direct current resistivity and gravity data: A case study of uranium bearing target rock

Interpretation of a single geophysical data set is not sufficient to get complete subsurface information. Cooperative or joint inversion of geophysical data sets is the preferred method for most case studies. In the present study, we present the results of the cooperative inversion approach of direct current resistivity and gravity data. The algorithm uses fuzzy c-means clustering to determine the petrophysical relationship between density and resistivity to obtain the similarity. Synthetic data set has demonstrated that the cooperative inversion approach can produce more reliable and better resistivity and density models of the subsurface as compared to those obtained through individual inversions. To utilize the presented cooperative inversion algorithm, the number of geologic units (number of clusters) in the study region must be known a priori. As a field study, the cooperative inversion approach was used to identify the extension of uranium-bearing target rock around the Beldih open cast mine. We noted the inconsistencies in both resistivity and density models obtained from the individual inversions. However, the presented cooperative inversion approach was able to produce similar resistivity and density models while maintaining the same error level of the respective individual inversions. We have considered four geologic units in the presented cooperative inversion as a field case study. We have also compared our cooperative results with drilled borehole and found to be a reliable tool to differentiate between the target rocks (kaolinite and quartz–magnetite–apatite rocks) and the ultramafic rock (host rock quartzite/alkaline granite). However, this study is subject to certain limitations such as the inability to differentiate between closely spaced kaolinite and quartz–magnetite–apatite rocks.     

岩石破裂过程中电阻率变化机理的探讨

受压岩石在破裂过程中,视电阻率会出现明显的变化,其异常形态与实验条件有很大的关系. 实验中对磁铁石英岩样品施加了单轴压缩,岩石的破裂经反复加载和卸载实现,并在岩样的裂隙中注入了食盐溶液. 在实验的各阶段,对样品的主剖面重建出一系列内部真电阻率分布的图像,揭示了介质内的微细结构,从而探讨了视电阻率变化的原因. 实验发现,岩石中裂隙的存在及所含液体的饱和状态,是岩石在主破裂前控制电阻率变化的两个最重要的因素;低应力状态属常态导电过程,孔隙度的变化是主要因素;高应力状态属裂隙表面导电机制,随着破裂面在岩体内部出现,水和孔隙有了完全贯通的平面,多种导电机制都得以发挥作用. 此外,体导电结构的变化在宏观上表现为各向异性和图样有序性的增强.     

坑道直流电阻率法超前探测的快速反演

在坑道电阻率超前探测工作中,视电阻率异常极值位置与异常体位置、厚度、电性以及产状相关.设计有效的反演方法对异常体的各种参数综合反演是非常必要的.首先利用有限元数值模拟技术分析并消除坑道空腔对视电阻率的影响,并将坑道超前探测视电阻率曲线转化为全空间视电阻率曲线.然后采用最小二乘法对超前探测视电阻率曲线进行快速反演.反演结果可准确反映围岩电阻率、异常体的电性、位置和产状;而由于同层等值现象,反演结果只能确定异常体的厚度和电阻率的组合值.