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松科2井东孔是松辽盆地科学钻探工程的主体钻孔,按照计划在全井段进行地球物理测井资料采集,为深部资源勘探及白垩纪古气候、古环境研究提供准确和全面的地球物理信息.在诸多测井方法中,自然伽马测井和自然伽马能谱测井能够测量地层的天然放射性强度和铀、钍、钾元素含量等参数,被有效地应用于放射性矿床勘查,尤其是铀资源的勘查与研究;电阻率、声波、密度和中子测井等常规测井和核磁共振成像、电阻率成像、元素俘获谱测井等特殊测井能够获取地层岩性和物性参数等信息,为铀矿勘查提供有力支持.本文利用松科2井东孔自然伽马测井资料来识别高放射性异常层;基于常规测井与特殊测井资料,结合前人的地质研究成果,分析放射性异常层的特征和成因.核测井曲线指示营城组存在两段高放射性异常层,深度分别为3096.8~3102.8 m（I号层）、3168.3~3170.9 m（Ⅱ号层）.I号层自然伽马值最高达360 API,铀含量范围20.5~29.3 ppm,综合测井和岩心资料判断该层为砾岩,具有铀成矿潜力;分析表明,构造条件和后生改造作用是影响I号层铀富集的关键因素,推测断裂-火山活动和盆地抬升剥蚀为含铀地下水及油气运移至I号层提供了通道,油气的后生还原作用最终导致了I号异常层的铀富集.Ⅱ号层自然伽马值最高达250API,钍含量22.4~37.3 ppm,铀含量5.9~11.0 ppm,为集块熔岩及凝灰岩,高放射性异常可能是高钍含量的流纹质成分和粘土矿物对铀的吸附作用导致的.松科2井东孔营城组高放射性异常层具有埋藏深度深、铀含量高等特点,表明松辽盆地深部具有找铀矿前景. 相似文献
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微电阻率扫描成像测井可以提供高分辨率的岩性图像,但目前对它的应用还仅仅限于定性分析。FMI静态图像数据是一组色标值阵列,其数值反映了电阻率的高低。碎屑岩地层按其粒度大小划分为泥质、粉砂质和砂质3种岩性,将图像色调信息通过他们的电阻率定量转换为岩性信息。建立了基于图像面积分割原理将FMI图像转换为3种岩性的相对含量的方法,实现了将FMI成像测井与常规测井联合处理解释以获得高分辨率的、定量的砂泥体积含量岩性剖面及半定量的钙质胶结强度等信息。实例表明,该方法可以定量计算碎屑岩的岩性粒度剖面,进而得到测井相剖面和辅助沉积微相解释。 相似文献
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大陆钻探区地震资料的解释正确与否取决于对该区确定地震波速模型, 地震波速模型的确定是反射地震处理极为困难的问题.中国大陆科学钻探提供了难得的深孔岩性、构造与地球物理测井资料,可以对结晶岩区地震资料时深转换的精度与地震波速模型的确定进行检验.本文介绍了科学钻探前根据地表资料建立波速模型的方法及钻探后由钻孔资料建立波速模型的方法.由地表资料建立的波速模型其精度分布是不均匀的,其波速反演的方差将随深度成正比地放大,在有钻孔时应尽量根据钻孔资料加以修正.由地球物理测井和岩芯的波速测试结果建立的波速模型结予波速估计值均匀的约束,说明由钻孔资料取得的波速模型可以有效地降低在深部的误差,提高地震反射与岩性变化和波阻抗合成的地震道之间的相关性.为检验波速模型,由测井资料与波速模型作出的合成地震道与反射地震剖面对比时还必须考虑到井孔的实际轨迹,否则对比相关性可能明显减小. 相似文献
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苏鲁超高压变质带的研究对了解发生在地幔深处的大陆动力学作用具有重要意义.近年来在此带中进行了大陆科学钻探和以深反射地震为主导的详细的综合地球物理调查,为研究超高压变质带地壳上地幔组构提供了难得的基础资料.根据大陆科学钻探工程的安排,在钻探取心,测井和地面三维地震观测的同时,还在5000 m的钻孔中用三分量数字检波器,对地表激发传播到井中的地震波场作垂直地震剖面（VSP）观测,目的是将传感器放在钻孔内,近距离、高精度和高分辨率地观测井周围由于超高压变质带的构造特征和岩石岩性特征引起的波场变化.通过零偏移距和非零偏移距VSP调查,我们首次在超高压变质带取得了深度达5000 m的精细的横波速度和泊松比等地球物理属性数据,作出了钻井岩心柱、测井、VSP纵波速度、横波速度和纵横波速度比、VSP上行波和地面地震资料的桥式综合对比图,使不同尺度的地质和地球物理调查资料互相连接在一起. 零偏和非零偏VSP观测可以标定主孔地质剖面各深度地质体的地震反射特性、井旁地震剖面上各个同相轴的地质属性,并对井旁局部地质构造作精细成像.由此观测取得的横波速度资料,成为建立孔区横波速度模型主要的资料来源,这种模型也是地面多波观测数据处理不可缺少的.因此,建议在进行大陆科学钻探时尽可能安排VSP地震调查. 相似文献
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在岩石地层分析和测年实验分析的基础上,综合运用地球物理测井、浅层反射地震和古地磁测年等多种地球物理方法划分河北平原厚覆盖区第四纪地层.通过对QHJ01孔的岩芯观察,按照沉积物岩性、颜色、沉积组合和沉积环境分析将揭露的松散沉积物分为8大岩性段.根据QHJ01孔古地磁样品磁倾角变化划分古地磁极性带,0～82.8 m为布容正极性时,82.8～235.8 m为松山反极性时,235.8 m以下为高斯正极性时.综合运用古地磁、浅层地震、地球物理测井方法和岩石地层分析判断第四系和中更新统底界分别为235.8 m和82.8 m,运用地球物理测井结合C14、光释光测年实验和岩石地层分析判断上更新统和全新统底界分别为53.3 m和24.9 m. 相似文献
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针对性选取东南沿海露头剖面18条,采集245件南海盆地基底可能出现的岩性样品,测定其密度和磁化率,建立各种岩性的密度-磁化率交会图版,以此约束过井地震剖面和重磁异常的地质解释,总结出南海北部盆地基底火山岩、侵入岩、变质岩和沉积岩4大类11亚类岩性的地震-重磁响应特征.应用重磁震-岩性解释模型逐一对南海盆地北部主干剖面进行地质-地球物理综合解释,从而实现了盆地基底岩性的平面填图.这种从盆缘剖面到盆地内部、从岩石物性测量到地质-地球物理综合解释的方法,在资料获取难度大、地质条件复杂的南海盆地基底地质研究中,业已证明是行之有效的,相信在其他盆地研究中也会有借鉴意义. 相似文献
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庐枞盆地浅表地壳速度成像与隐伏矿靶区预测 总被引：4，自引：2，他引：2
利用反射地震初至波可以精确反演地壳速度结构和构造信息.对庐枞盆地采集的高分辨地震数据,运用初至波层析成像方法,反演得到了该区1200 m以上的浅表地壳速度结构信息.找矿信息总是同地球化学异常联系紧密,对采集于炮孔深处的岩屑、泥砂样品进行了地球化学分析,发现了多处显著的金属元素异常.对五条测线的速度成像结果及其映射的地下岩性结构和炮孔地球化学分析结果进行了相关性对比分析.结果显示,庐枞盆地的沉积岩、火山岩和侵入岩具有不同的速度范围,侵入岩具有高波速特征,地球化学信息高异常往往出现在高速侵入岩体的上方;精细的速度信息蕴含着丰富的浅表地壳结构变化特征,与庐枞矿集区已知的地质、岩体、构造和矿体分布存在着良好的对应关系.速度成像结果可以准确刻画地下隐伏侵入岩体的空间分布形态,结合地球化学分析异常和重磁探测等信息,预测隐伏矿床,提供深部找矿靶区. 相似文献
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Geophysical signatures of uranium mineralization and its subsurface validation at Beldih,Purulia District,West Bengal,India: a case study 
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下载免费PDF全文 Animesh Mandal W.K. Mohanty S.P. Sharma Arkoprovo Biswas Joydip Sen A. K. Bhatt 《Geophysical Prospecting》2015,63(3):713-726
The Beldih open cast mine of the South Purulia Shear Zone in Eastern India is well known for apatite deposits associated with Nb–rare‐earth‐element–uranium mineralization within steeply dipping, altered ferruginous kaolinite and quartz–magnetite–apatite rocks with E–W strikes at the contact of altered mafic–ultramafic and granite/quartzite rocks. A detailed geophysical study using gravity, magnetic, and gradient resistivity profiling surveys has been carried out over ～1 km2 area surrounding the Beldih mine to investigate further the dip, depth, lateral extension, and associated geophysical signatures of the uranium mineralization in the environs of South Purulia Shear Zone. The high‐to‐low transition zone on the northern part and high‐to‐low anomaly patches on the southeastern and southwestern parts of the Bouguer, reduced‐to‐pole magnetic, and trend‐surface‐separated residual gravity–magnetic anomaly maps indicate the possibility of highly altered zone(s) on the northern, southeastern, and southwestern parts of the Beldih mine. The gradient resistivity survey on either side of the mine has also revealed the correlation of low‐resistivity anomalies with low‐gravity and moderately high magnetic anomalies. In particular, the anomalies and modeled subsurface features along profile P6 perfectly match with subsurface geology and uranium mineralization at depth. Two‐dimensional and three‐dimensional residual gravity models along P6 depict the presence of highly altered vertical sheet of low‐density material up to a depth of ～200 m. The drilling results along the same profile confirm the continuation of uranium mineralization zone for the low‐density material. This not only validates the findings of the gravity model but also establishes the geophysical signatures for uranium mineralization as low‐gravity, moderate‐to‐high magnetic, and low‐resistivity values in this region. This study enhances the scope of further integrated geophysical investigations along the South Purulia Shear Zone to delineate suitable target areas for uranium exploration. 相似文献
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Björn Heincke Thomas Günther Einar Dalsegg Jan Steinar Rønning Guri Venvik Ganerød Harald Elvebakk 《Journal of Applied Geophysics》2010,70(4):292-306
We present a combined 3-D geoelectric and seismic tomography study conducted on the large Åknes rockslide in western Norway. Movements on the slope are strongly influenced by water infiltration, such that the hydrogeological regime is considered as a critical factor affecting the slope stability. The aim of our combined geophysical study was to identify and visualize the main shallow tension fractures and to determine their effect on hydraulic processes by comparing the geophysical results with information from borehole logging and tracer tests. To resolve the complex subsurface conditions of the highly fractured rock mass, a three-dimensional set-up was chosen for our seismic survey. To map the water distribution within the rock mass, a pattern of nine intersecting 2-D geoelectric profiles covered the complete unstable slope. Six of them that crossed the seismic survey area were considered as a single data set in a 3-D inversion. For both methods, smoothing-constraint inversion algorithms were used, and the forward calculations and parameterizations were based on unstructured triangular meshes. A pair of parallel shallow low-velocity anomalies (< 1400 m/s) observed in the final seismic tomogram was immediately underlain by two anomalies with resistivities <13 kΩm in the resistivity tomogram. In combination with borehole logging results, the low-velocity and resistivity anomalies could be associated with the drained and water-filled part of the tension fractures, respectively. There were indications from impeller flowmeter measurements and tracer tests that such tension fractures intersected several other water-filled fractures and were responsible for distinct changes of the main groundwater flow paths. 相似文献
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A suite of electrical, radiation, and mechanical borehole probes were run in a 76-mm-diameter borehole drilled to a slant depth of 380 m in leptite and granite. The hole is located in Precambrian bedrock in central Sweden where a site is dedicated to in-situ experiments pertaining to the disposal of radioactive wastes. The challenge to borehole logging methods for such site investigations is to resolve geological features and fluid flow parameters in geological sites which are initially chosen for their homogeneity, low porosity, and minimal fracturing. The Stripa borehole is characterized by high electrical resistivity values in the 20–100 kΩm range, by acoustic velocities around 5800 m s-1 (which is close to laboratory values on intact specimens), and by total porosity of around one volume percent. In this context, probe resolution was adequate to produce interpretable information on almost all of the logs. Two principal rock types were encountered in the hole: granite, of quartz monzonitic composition, and leptite. The granite and leptite intercepts are subdivided into units characterized by mafic mineral content, sulfide mineral content, and electrical and radiation properties. Iron-rich zones in the leptite are highly anomalous on the gamma-gamma and neutron logs; thin mafic zones in the granite can also be distinguished. Occurrences of a few percent pyrite are detected by the electrical, gamma-gamma, and neutron logs. Although overall porosity is quite low throughout the hole, analysis of the resistivity and neutron logs indicates the porosity increases by a few volume percent at fracture zones. The differential resistance and caliper probes detect borehole diameter roughness of less than 1 mm, helping to confirm acoustic waveform anomalies which are indicative of fracture zones. Compres-sional wave transit time and shear-wave interference patterns usually occur coincident with open fractures observed in core, the correlation being especially good at major fracture zones. 相似文献
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基于青藏高原多年冻土区三个钻孔的地球物理测井数据和钻孔编录资料,我们对多年冻土厚度和多年冻土层内地下冰与地球物理测井数据之间的关系进行了相关的分析研究.研究表明,当地层为土壤类型时,可以使用井径和侧向测井曲线来判断多年冻土层厚度;而当地层为致密的基岩时,不能使用上述两种测井曲线来判断多年冻土层厚度.此外,还可以使用长源距伽马-伽马曲线和侧向测井曲线来识别多年冻土层内部分地下冰层的位置,其前提条件是地下冰层具有一定的厚度,或即使厚度较薄,但连续出现.这一研究结果对于利用地球物理测井曲线来调查多年冻土情况具有一定的应用价值. 相似文献
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南海北部陆架西区盆地地质、地球物理场特征及其深部结构 总被引：8，自引：6，他引：8
分析了南海北部陆架西区盆地的地质、地球物理场特征，计算了研究海域重、磁资料的1阶小波细节、4阶小波逼近变换。根据分析与计算可知，研究区的布格重力异常以北西低的负值，东南高的正值为特征。在东部及东南部异常等值线走向为北东；西部异常等值线以北西走向为特征；西北地区异常以北东东、北东走向的局部等值线圈闭为特征。磁场的展布十分复杂，按磁异常的变化程度可分为三个变化区，即磁异常平静区、剧变区及缓变区。磁异常的平静区位于研究区的西部，即莺歌海盆地所在位置，这一带磁异常等值线极为稀疏，异常值为负背景异常。剧变区位于海南岛，该地区的磁异常变化极为剧烈，异常特征以局部小圈闭为特征，等值线分布密集。磁异常的平缓区位于平静区及剧变区之外的其它地区。琼东南盆地、北部湾盆地的磁异常具有此特征。根据重、磁场资料以及南海北部盆地钻井取样的测试结果、同时参考穿越南海地学断面的结果，对研究区的地壳结构进行了反演计算，计算表明南海陆架盆地区域地壳结构较为复杂，研究区的地壳厚度在22－33km之间，总的趋势由陆向洋地壳厚度逐渐减薄，反映出该区域地壳具有陆壳、拉伸陆壳、过渡壳的性质，同时存在有上地幔隆起区及凹陷区。磁性底界面厚度在17－24km之间变化，其中在莺歌海盆地较深，在海南岛地区磁性界面较浅。 相似文献
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Gold, as a trace element, is not directly detectable by geophysical borehole logging techniques. Geophysical logging methods have therefore been used to infer the presence of structural features and alteration processes associated with gold. Since these features and processes differ with the style of gold mineralization, a unique relation between geophysical anomalies and gold cannot be established. However, in a particular environment, such an association can be established. We examined geophysical log data (self potential, induced polarization, resistivity, gamma, temperature, and temperature gradient) and drill core from the Barber-Larder property in NE Ontario. The geophysically detectable alteration processes associated with gold were identified as sericitization and pyritization, by means of factor analysis. A linear discriminant function was constructed which allowed the zones of economic mineralization (nominally 0.05 oz/ton or 1.5 ppm) to be identified with a 75% success rate based on geophysical log data alone. This rate was achieved without sophisticated non-linear data transformations. 相似文献
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Electrical resistivity and seismic refraction studies for groundwater in the Jodhpura area,Rajasthan
Summary The results of geophysical investigations carried out for groundwater employing seismic refraction and electrical resistivity methods near Jodhpura (27o4730N:75o4240E) in the Jhunjhunu District, Rajasthan, are presented. Prominent resistivity low zones, revealed by the resistivity profiles, are indicative of deeper section of unconsolidated sediments overlying the bedrock and are usually favourable locations for groundwater. An equiresistivity and water-level contour map based on well data is furnished, indicating the fresh water zone boundary deduced geophysically. Longitudinal velocities for the various rock types occurring in and around the area are tabulated for general interest. A bedrock map prepared on the basis of depths estimated geophysically is incorporated. The depths to bedrock computed from electrical and/or seismic data compare well with those obtained from borehole data. 相似文献
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H. C. Soffel Ch. Bücker H. Gebrande E. Huenges E. Lippman J. Pohl A. Rauen A. Schult K. M. Streit F. Wienand 《Surveys in Geophysics》1992,13(1):1-34
The project of an ultradeep drill hole (KTB) in the Oberpfalz area at the western margin of the Bohemian Massif has completed a pilot drill hole to a depth of 4000.1 m in April 1989. This well is situated only about 200m away from the main drill hole aimed at 10 km depth where drilling started in September 1990. The cores of the pilot well have a diameter of 9.4 cm or 10.16 cm, respectively. In addition to cores and cuttings there was also mud available for geochemical, petrological and some geophysical measurements. The pilot drill hole has a core recovery length of as much as 3042.6 m (about 76%), among which 193.1 m were obtained by rotary drilling and 2849.5 m by wireline drilling. Several petrophysical parameters were measured in a specially established field laboratory at the drill site immediately after sampling in order to obtain as good as possible in-situ values. Results for the following parameters are reported: density, natural gamma ray activity, velocities of seismic longitudinal and shear waves, thermal conductivity, electrical resistivity, natural remanent magnetization, magnetic susceptibility, porosity and inner surface. The methods of measurement are characterized briefly and the results of the pilot drill hole are presented and discussed in connection with the lithology and the geophysical anomalies, which have been observed on the surface. 相似文献
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如何开展老矿山后备资源的寻找与定位预测--工作程序与实例分析 总被引：4，自引：4，他引：0
在老矿山的深部与外围寻找新的可用资源,要求勘探者具备新的找矿思路、行之有效的深部探测手段与合理的工作程序、新的找矿思路来自于研究者的相关知识储备和创新能力,使其不墨守成规,用新的视角重新认识矿化规律和控矿要素。进而在老矿区优选出潜在的有利成矿区段．行之有效的深部探测手段以其高分辨的数字图像,不仅可以客观地反映深部地质结构的各种变化及矿化信息,以验证地质推测的可靠性,而且借助属地化的解释模型对矿区深部和外围开展真正意义的矿体定位预测、同时还可以大大降低工程验证的盲目性和巨大浪费．根据我们目前拥有的先进地球物理深部探测手段和大量老矿山找矿的经验与教训,逐渐形成了一套实用的工作程序。 相似文献