应用TEM资料分析麻黄泉地区地层结构及沉积环境

为了在酒东盆地中寻找隐伏的砂岩型铀矿,需要研究麻黄泉地区的地层结构及沉积环境。通过开展瞬变电磁测量及相应的数据处理,建立了该区视电阻率与不同岩性的对应关系,根据岩性视电阻率差异,划分了盆地基底构造单元,确定测区存在3个大的视电阻率电性层,解释出沉积中心和冲积扇的空间位置。结合砂岩型铀矿的控矿因素,认为解释的斜坡区及冲积扇可作为下一步开展找矿工作的重点地段。     

多参数分析在孟公界铀矿床探测中的应用研究

孟公界铀矿床与韧-脆性剪切带密切相关,铀矿化通常伴有赤铁矿化、黄铁矿化,矿化岩石与围岩间存在明显的物性差异。在测区布设激电观测剖面并利用半衰时、视极化率、视电阻率异常的分布准确地推断出隐伏铀矿(化)体的空间位置与赋存状态,钻孔揭露表明激发极化法在孟公界铀矿探测效果显著。     

利用瞬变电磁测量数据进行岩性、岩相划分及沉积体系识别

沙枣泉盆地内铀矿化与扇前缘亚相关系密切。根据测区岩性视电阻率的差异,开展盆地内瞬变电磁测量及相应的数据处理,建立测区视电阻率与不同岩性的对应关系,划分了不同岩性、岩相在平面上的分布范围,识别了冲积扇沉积体系,解释出扇前缘亚相的空间位置。从后期钻探验证结果看,效果非常明显。     

瞬变电磁测深法在公婆泉地区寻找砂岩型铀矿中的应用

通过瞬变电磁测深方法在公婆泉地区寻找砂岩型铀矿中的应用，以视电阻率断面特征的定性分析，结合孔旁测深、正演拟合、反演计算，划出了4个大的地层界面。根据地层的隆起、凹陷特征分析了地下水的补、径、排条件。探讨了砂岩型铀矿成矿地质环境。     

应用电测井曲线研究岩矿石渗透性

详述了合理利用综合测井中的自然电位、视电阻率曲线定量解释确定含矿含水层渗透性和非渗透性岩矿石。为快速评价铀矿床提供可靠的依据，对于砂岩型铀矿的预测和勘探具有重要的意义。     

倾斜线源的三维电场数值模拟研究

利用倾斜线状电流源的理论电位式和有限差分法理论,建立三维离散化方程组,并用ICCG法求解该方程组,设计三维电阻率异常体分布模型,经计算得到了地表视电阻率分布在垂直和倾斜线源情况下的变化规律。以上工作对利用直流电法勘探方法,来解决油田剩余油的分布及对地浸砂岩型铀矿矿层渗透性能的分析,有着实际的意义。     

基于瞬变电磁法探究中高阶煤层瓦斯含量与视电阻率关系的试验

为掌握煤层瓦斯分布规律,揭示煤层瓦斯含量与视电阻率的关系,结合实验室关于煤样电阻率的研究,使用瞬变电磁法研究煤层视电阻率与瓦斯含量的相关性,在豫西新安煤矿进行18次探测试验,获取有效数据21组。研究表明:煤层视电阻率与瓦斯含量呈较好的负相关,瓦斯含量每升高1 m3/t,视电阻率对数值降低6.6%~20%,判定系数为0.621 9~0.753 1,说明煤层视电阻率对瓦斯含量具有明显的响应特征,利用瞬变电磁可以在相似地质条件下探测煤层瓦斯含量高低及其分布规律。      

瞬变电磁测深结果的定性分析及定量解释

通过对公婆泉盆地吐路一驼马滩地区瞬变电磁测深视电阻率断面特征的分析，结合孔旁测深正演拟合，反演计算等，以定性分析、定量解释方法对该区地层进行了四个大的地层界面推断划分。为该区的铀矿找矿地质环境的分析提供了依据。     

ZH404多参数组合测井探管研制

论述了ZH404多参数组合测井探管的设计思想,针对探管设计的技术难点,提出了解决方法,最终完成探管的电子电路设计、软件设计和机械结构设计等。适用于小口径钻孔铀矿测井的ZH404多参数组合测井探管能够一次测井同时获取γ总量、钻孔方位角、钻孔顶角、自然电位、视电阻率和单点电阻等6种参数,大大提高了测井的工作效率,降低了劳动强度和测井成本,具有显著的经济效益。     

论直流激发极化法的视电阻率参数

直流激发极化法,计算视电阻率的一次场采集于供电方波的末端时间,从而包含了被激发形成的二次场。在高极化率地质体上,得到的视电阻率将削弱其低阻特性或放大高阻特性。为此,建议在野外工作中,应对所采集的一次场作适当的处理后,再计算视电阻率,以降低这种影响。     

Integrated geophysical studies to elicit the subsurface structures associated with Uranium mineralization around South Purulia Shear Zone,India: A review

South Purulia Shear Zone in India is an important zone that hosts uranium mineralization. Since detailed geophysical studies have not been carried out in this region, an integrated geophysical study using self-potential, resistivity, very low frequency electromagnetic and radiometric methods was performed to identify the subsurface structures that could host the hydrothermally altered uranium deposits in the area. The study reveals the wide and large magnitude of negative self-potential anomaly across the South Purulia Shear Zone. The peak negative self-potential anomalies are correlated with the low gravity and low resistivity anomalies measured along various profiles. The low self-potential, gravity and low resistivity anomaly zones are also correlated with conducting zones inferred from very low frequency electromagnetic measurements. Interpretation of self-potential data reveals multiple thick sheet-type vertical and/or inclined structures which might be associated with uranium mineralization. Schlumberger resistivity sounding data reveals an increasing trend of apparent resistivity with current electrode separations/depth. Apparent conductance measured simultaneously with resistivity measurement reveals an increase in current flow of current as depth increases. This exhibits the presence of thin conducting layers at these depths, which is not reflected in resistivity sounding data due to suppression problem. Also this conducting layer is consistent in various soundings and is connected from Raghunathpur to the South Purulia Shear Zone. Correlation of very low frequency and self-potential data shows that the structures are comparable and a radiometric profile also advocate that the conducting structure is associated with radioactive minerals. These structures are likely to be mineralized zones as hydro-uranium anomaly has also been reported from various locations in the area. Moreover, drilling results at a specific mine near the study area also confirms the presence of uranium mineralization. The hydrothermal activity associated with uranium mineralization seems to be still active in the area. Such combined geophysical studies are essential to understand this highly complex shear zone for the economic exploitation of its natural resources.     

砂岩型铀矿地浸开采过程中电法勘查技术的应用

原地浸出采铀是一种利用砂岩型矿层对水的渗透性,采用注、抽液孔向含矿岩层注入“溶浸液”和抽取“浸出溶液”而获得铀的先进采矿技术。研究井场下方 “浸出液”分布范围,不仅能掌握矿体的被覆盖程度和矿床开采率,且对于地下水体污染监控具有重要意义。对内蒙古二连盆地某铀矿地浸开采试验基地进行电法勘查,以对铀矿地浸开采过程进行监测试验。具体采用可控源音频大地电磁测深法(CSAMT)和时间域激发极化法对试验井场进行探测试验。试验区以抽孔为中心布设一个18×18的测网,测网的线距和点距均为10 m。电法探测试验时,对穿过抽、注井的5条纵向和4条横向测线进行了CSAMT观测,并对全区进行中间梯度激发极化测量。经过数据处理和反演得到了中梯装置视极化率平面等值线图及CSAMT二维电阻率模型,并结合研究区域已知资料进行解释,认为电阻率断面上井场区域下方的低阻异常带反映了地浸开采过程“溶浸液”的地下分布状态;视极化率平面等值线图上显示的抽注单元下方的大片低极化率异常,可能是由地下浸出液与岩层组成的离子导电体系“薄膜极化”效应产生的异常带。     

钱家店凹陷赋铀岩系姚家组高分辨率层序地层学研究

姚家组为一套中细粒辫状河流沉积。在高分辨率层序地层学基本理论指导下,笔者通过岩心观察、岩石化学组分分析、自然电位及视电阻率测井等手段,建立了赋铀岩系姚家组高分辨率层序地层格架,探讨了中期旋回内地层结构、古地形和沉积微相与铀矿床形成的关系。     

Controlled Source Audio Magneto Telluric (CSAMT) studies for uranium exploration in Durgi area,Palnad sub-basin,Cuddapah basin,India

Cuddapah basin is known for hosting unconformity proximal uranium deposits viz., Lambapur, Peddagattu, Chitirial and Koppunuru along the northern margin of the basin. It is well known that these deposits are mostly associated with basement granitoids in Srisailam Sub-basin, and with cover sediments in Palnad subbasin where basement topography and fault/fracture system influence the fluid flow causing basement alteration and ore deposition. Geological setup, surface manifestation of uranium anomalies and association of the hydro-uranium anomalies near Durgi area in southern part of the Palnad sub-basin, have prompted detail investigation by geophysical methods to probe greater depths. Controlled Source Audio Magneto Telluric (CSAMT) survey conducted over five decades of frequency (0.1-9600 Hz) delineated the various lithounits of Kurnool and Nallamalai Groups along with their thicknesses as there exist an appreciable resistivity contrast. Interpretation of CSAMT sounding data are constrained by resistivity logs and litholog data obtained from the boreholes drilled within the basin indicated three to four layered structure. Sub-surface 2-D and 3-D geo-electrical models are simulated by stitching 1-D layered inverted resistivity earth models. Stitched 1-D inverted resistivity sections revealed the unconformity between the Kurnool Group and Nallamalai Group along with basement undulations. The faults/fractures delineated from the CSAMT data corroborated well with the results of gravity data acquired over the same area. Simulated 3-D voxel resistivity model helped in visualising the faults/fractures, their depth extent, thickness of the Banganapalle quartzite and basement configuration. Integrated interpretation of CSAMT, gravity and borehole data facilitated in delineating the unconformity and the structural features favourable for uranium mineralisation in deeper parts of the Palnad sub-basin.     

椭球体的视电阻率特征

椭球体是最具代表性的典型三维地电体之一,它三个轴的长短经过变化后可以和多种形状的地电体相似。因此,实现了椭球体电阻率的求解,就可以模拟绝大多数三维地电体的电阻率曲线。从拉普拉斯方程的求解出发,得到了均匀空间中存在的水平椭球体异常表达式,并用简单加倍的方法得到了均匀半空间中水平椭球体的视电阻率公式,结合倾斜旋转椭球体的视电阻率公式的规律,得到了倾斜椭球体的视电阻率公式,再进行一系列简化得到板状体。最后分析对比了均匀电场中旋转椭球体和板状体的视电阻率曲线的形态和规律。结论表明:旋转椭球体与板状体的视电阻率曲线的走向大体相似,且板状体的曲线相比旋转椭球体较缓和。对于低阻情况,在异常体顶部附近的视电阻率异常为零,异常体的倾向一侧有极小值,反倾向一侧有极大值,曲线随倾角α的增大而逐渐变陡。对于高阻情况,视电阻率的极大值出现在异常体顶部附近,两侧有极小值,倾向一侧的曲线较缓和而反倾向一侧的曲线较陡峭,随着倾角α的增大,视电阻率异常变大。     

Relation between source rock properties and wireline log parameters: An example from Lower Jurassic Posidonia Shale, NW-Germany

The relationships between source rock quality and wireline log parameters were established for the Lower Jurassic Posidonia Shale, the most prolific petroleum source rock of Central Europe. Wireline logs used are the gamma ray spectrometry, density, sonic and various resistivity logs. The organic geochemical parameters considered include the organic carbon content, hydrogen index, and the hydrocarbon potential expressed by pyrolysis yield. The case history presented is based on a continuous core through the entire Posidonia Shale interval from a location where this source rock is immature. Care was taken to detect and to avoid samples and log values influenced by bore hole roughness and fractures. Fair correlations were observed only between uranium content from gamma ray spectrometry log and organic carbon content. No correlation was recognized between uranium content and kerogen type as defined by hydrogen indices. For various reasons density, sonic, and resistivity logs did not provide useful data in this study.Three rock units with irregular, high and low uranium contents could be differentiated. Possible causes for this tripartition are different environments during deposition and postdepositional redistribution of uranium during early diagenesis and in association with fractures.     

关于频率电磁测深几个问题的探讨(三)——频率电磁测深相位问题分析

频率电磁测深复电阻率含有振幅视电阻率和相位,相位既可由复电阻率的虚部和实部表示,也可通过振幅视电阻率转换得出。阐述了振幅视电阻率转换为相位的原理和计算公式。根据典型地电模型计算的振幅视电阻率曲线和相位曲线,分析了相位曲线与振幅视电阻率曲线的关系及特点。分析结果表明,相位曲线变化幅度更大,相应频率更高,可提高对地层的分辨率,加大探测地层深度。将振幅视电阻率和相位资料结合解释,可提高解释的地质效果。      

Geophysical anomalies associated with uranium mineralization from Beldih mine, South Purulia Shear Zone, India

Beldih mine at the central part of the South Purulia Shear Zone (SPSZ) has been reported with low grade uranium-bearing formation within quartz-magnetite-apatite host in kaolinized formation. Therefore, the present integrated geophysical study with gravity, magnetic, radiometric, very low frequency electromagnetic (VLF) and gradient resistivity profiling methods around the known mineralized zones aimed at identifying the exact geophysical signatures and lateral extent of these uranium mineralization bands. The closely spaced gravity-magnetic contours over the low to high anomaly transition zones of Bouguer, reduced-to-pole magnetic, and trend surface separated residual gravity-magnetic anomaly maps indicate the possibility of high altered zone(s) along NW-SE direction at the central part of the study area. High current density plots of VLF method and the low resistive zones in gradient resistivity study depict the coincidence with low gravity, moderately high magnetic and low resistivity anomalies at the same locations. Moderate high radioactive zones have also been observed over these locations. This also suggests the existence of radioactive mineralization over this region. Along profile P2, drilled borehole data revealed the presence of uranium mineralization at a depth of ～100 m. The vertical projection of this mineralization band also identified as low gravity, low resistivity and high magnetic anomaly zone. Thus, the application of integrated geophysical techniques supported by geological information successfully recognized the nature of geophysical signatures associated with the uranium mineralization of this region. This enhances the scope of further integrated geophysical investigations in the unexplored regions of SPSZ.     

电磁测深法视电阻率定义问题的研究

本文首先提出电法勘探中视电阻率定义的基本原则,并以此为依据讨论了MT法、TEMS法及FEMS法中各种视电阻率定义的优缺点,提出了改进办法.研究发现,MT法利用面阻抗实部或在时间域中给出的视电阻率是很有效的定义方法,能很好地区分良导层,而面阻抗虚部定义的视电阻率效果最差.对TEMS法来说,利用视电阻率全区定义较通常的远区或近区近似定义更有效.研究还表明,由磁场时间导数定义的全区视电阻率有时出现多解性甚至无解,而利用磁场本身定义的视电阻率是很有效的.对FEMS法,进行了类似的全区视电阻率定义问题讨论,虽然取得的结果不如TEMS法理想,但比起目前常用的大、小感应数条件下定义的视电阻率响应还是有一定效果.文中对电磁测深法中出现的视电阻率响应曲线的假极值效应进行了物理解释.