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This study integrated surface and subsurface stratigraphic data with geophysical logs and hydrogeologic data in order to
characterize the hydraulic properties of the Silurian dolomite in northeastern Wisconsin. Silurian stratigraphy consists of
predictable alternations of characteristic facies associations. A vertical profile of hydraulic conductivity, obtained from
short-interval packer tests in a core hole that penetrates a majority of the Silurian section, indicates that hydraulic conductivity
ranges over five orders of magnitude (10–1 to 10–6 cm/s). Matrix conductivity is generally low and varies with texture; the finer-grained restricted-marine and transitional
facies being less permeable than the coarser-grained open-marine facies. High-conductivity values are generally associated
with bedding-plane fractures, and fracture frequency is greater in the restricted-marine facies.
High-flow features in 16 wells were identified using fluid-temperature/resistivity and heat-pulse flowmeter logs. Natural-gamma
logs were used to identify the stratigraphic position of flow features in each well and to correlate flow features to specific
stratigraphic horizons. By combining stratigraphic, geophysical, and hydrogeologic data, 14 high-permeability zones within
the Silurian aquifer have been identified and correlated in wells more than 16 km apart. These zones parallel bedding, appear
most pronounced at contacts between contrasting lithologies, and are most abundant in restricted-marine lithologies.
Electronic Publication 相似文献
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Md. Hasan Imam Delwar Hossain A. S. M. Woobaid Ullah 《Journal of the Geological Society of India》2013,82(3):290-294
This study has been conducted to find out the aquifer characteristics of Bagerhat Sadar and adjacent areas in Bangladesh using geoelectrical resistivity method and borehole logs. The interpretation of resistivity soundings (14 nos.) shows that the sub-surface lithological sequence can be divided into four geoelectric units. The deepest geoelectric unit (with resistivity from 8 Ohm-m to 18 Ohm-m) represents the deep aquifer with usually fresh water. Resistivity values of 12 ?m or more for this unit may indicate formation water as acceptable for coastal people. In the study area, the shallow aquifer inferred is not suitable for groundwater development. 相似文献
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垃圾土渗透性和持水性的试验研究 总被引:5,自引:2,他引:3
通过室内常水头试验测定了垃圾土的饱和渗透系数,通过室内压力板仪试验测得垃圾土的土-水特征曲线。基于土-水特征曲线预测了垃圾土的非饱和渗透系数,并通过室内入渗试验进行了初步验证。常水头试验得到深层、中层和浅层垃圾土的饱和渗透系数分别为3.56×10-4、3.50×10-3、4.81×10-2 cm/s。土-水特征曲线试验表明,垃圾土饱和含水率和残余含水率较高,进气值很小,土-水特征曲线在低基质吸力时存在陡降段,其中浅层垃圾土的陡于深层垃圾。验证试验表明,预测得到的非饱和渗透系数与实测结果接近,基于土-水特征曲线预测垃圾土非饱和渗透系数的方法基本可行。 相似文献
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The groundwater flow regime at great depth within the Molasse Basin (SW Germany) was studied. Data relevant for a flow model at 600–1,600 m depth are sparse in the western part of the basin. However, temperature measurements are available covering much of the area at a wide range of depths. Therefore, a thermal 3D steady-state model was set up with the aim of comparing modeled with observed subsurface temperatures. Stratigraphic information from many boreholes was also available, but only a few values of rock thermal conductivity and heat-production rate could be obtained. Some strong thermal residual anomalies were identified with respect to the purely conductive model, especially along fault zones, and within stratigraphic layers with high hydraulic conductivity. These anomalies can be explained by various advective heat-transport mechanisms, yet most explanations can be eliminated. The most plausible constellation explaining the major positive thermal anomalies of 10 Kelvin and more is a fault zone of E–W strike, intersected by an aquifer with flow parallel to the fault zone. This concept was investigated by using a simplified type model. In spite of some shortcomings, the method presented here can be used to identify temperature anomalies, and to identify possible explanations. 相似文献
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Jean-Christophe Maréchal Jean-Michel Vouillamoz M. S. Mohan Kumar Benoit Dewandel 《Hydrogeology Journal》2010,18(8):1787-1796
A method to estimate aquifer thickness and hydraulic conductivity has been developed, consisting of multiple pumping tests. The method requires short-duration pumping cycles on an unconfined aquifer with significant seasonal water-table fluctuations. The interpretation of several pumping tests at a site in India under various initial conditions provides information on the change in hydrodynamic parameters in relation to the initial water-table level. The transmissivity linearly decreases compared with the initial water level, suggesting a homogeneous distribution of hydraulic conductivity with depth. The hydraulic conductivity is estimated from the slope of this linear relationship. The extrapolation of the relationship between transmissivity and water level provides an estimate of the aquifer thickness that is in good agreement with geophysical investigations. The hydraulically active part of the aquifer is located in both the shallow weathered and the underlying densely fractured zones of the crystalline basement. However, no significant relationship is found between the aquifer storage coefficient and initial water level. This new method contributes to filling the methodological gap between single pumping tests and hydraulic tomography, in providing information on the variation of the global transmissivity according to depth. It can be applied to any unconfined aquifer experiencing large seasonal water-table fluctuations and short pumping cycles. 相似文献
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The Mahoning River is one of the five most contaminated rivers in the U.S. This study characterized the contaminated sediments in the river banks and investigated the hydraulic interconnection between shallow aquifer in the banks with the river water. The study was conducted along the most polluted section of the river, which is 50-km long, using over 50 monitoring wells. The characterization part of the study investigated the sedimentology, hydraulic conductivity, and spatial distribution of the contaminated sediments. Results of the characterization revealed that the contaminated sediments consist of fine-grained sand, silt, mud, and clay. The spatial distribution of the contaminated sediment is heterogeneous and positively correlates with the hydraulic conductivity values, i.e., the greatest contamination occurs in high conductivity areas. Hydraulic conductivity was determined by the Hazen formula using 82 sediment samples. Bioremediation, which is one of the remedial options considered for the banks, is found to be hydraulically feasible because of sufficient hydraulic conductivity values (≥10?4 cm/s) that ensure reasonable rates of nutrient delivery. Monitoring of water levels in the river and groundwater for a 10-month period shows that flow occurs from the river to groundwater and vice versa. The exchange of flow is influenced by rainfall. Flow of groundwater to the river will continually transport the dissolved contaminants in groundwater to the river. Therefore, findings of this study show that one of the remedial options that proposes dredging of channel sediments and permits no action for bank sediments cannot be chosen due to river water–groundwater interactions. 相似文献
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高分辨率FMS成像测井资料在科学大洋钻探中的应用 总被引:1,自引:0,他引:1
FMS地层微电阻率扫描成像测井技术诞生于1986年,1989年首次在大洋钻探中获得应用。它采用纽扣电极阵列沿井壁纵向扫描方式采集地层的电阻率信息,经过适当的数字和图像处理后转化为井壁地层的二维微电阻率图像。FMS资料具有分辨率高(理论分辨率为5 mm)、连续原位测量及定向性等特点,是科学大洋钻探中岩芯地质分析方法的重要补充,具有其他地球物理方法难以替代的作用。从岩芯归位和定向、岩性岩相识别及地层剖面重建、沉积构造和古流方向分析、地层旋回性与古气候周期分析、浊积层厚度统计分析、构造和应力场分析及洋壳研究等7个方面对FMS在科学大洋钻探中的应用现状进行综述,对目前FMS成像测井资料应用中存在的问题及发展方向进行分析,包括利用率不高、定量分析成果欠缺、研究深度和广度有待拓展等。 相似文献
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利用ATmega8单片机研制了一种适用于检测几百m钻孔内地下水温度的数字式测温仪,能连续测量孔内某一点处的地下水温度。现场试验表明,这是一种简单、方便、经济、有效的方法,能解决浅层地热井温度检测的问题。介绍了该测温系统的测温机理、结构组成及其在地热勘探中的具体应用。 相似文献
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Accurate knowledge of pore pressure is fundamental to any safe and economic well construction. Here, we present results that
are indicative of over pressure zones (OPZ) for five wells drilled under the Krishna–Godavari offshore basin (KGOB) at the
Eastern Continental Margin of India (ECMI). OPZ in areas of crustal flexuring can act as potential geohazard while drilling.
These wells locate at water depths of 515–1,265 m, where their penetrated-vertical-depth reaches up to 3,960 m in clastic
sediments. pore pressure gradient (PPG) and fracture pressure gradient (FPG) are estimated from acoustic log for all five
wells, while the Normal Compaction Trend (NCT) and pore pressure are calculated from Miller’s sonic equation. Top of OPZ is
indicated by values that are higher than the NCT; departure from NCT is observed at depth intervals of 1,320–2,180 m, 1,700–3,960 m,
1,600–1,880 m, 1,420–2,609 m and 2,080–2,200 m for the respective Wells 1 through 5. The pressure data from Modular Dynamic
Tester (MDT) agree well with the pore pressure values obtained from the logs. The Overburden Gradient (OBG), PPG and FPG values
increase rather slowly with total depth in deeper-water of KGOB when compared to the wells located in shallow water depth.
Consequently, the operating safety margin between PPG and FPG decreases as the water depth increases, and this clearly leads
to an increase in the number of casing strings to reach the target depth. Certain basic conclusions on the potentiality of
natural hazard for drilling operations are drawn on the basis of these results, but evidently, further studies are warranted
to present a more composite picture of OPZ under KGOB. 相似文献
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Fractured-rock aquifers display spatially and temporally variable hydraulic conductivity generally attributed to variable fracture intensity and connectivity. Empirical evidence suggests fracture aperture and hydraulic conductivity are sensitive to in situ stress. This study investigates the sensitivity of fractured-rock hydraulic conductivity, groundwater flow paths, and advection-dominated transport to variable shear and normal fracture stiffness magnitudes for a range of deviatoric stress states. Fracture aperture and hydraulic conductivity are solved for analytically using empirical hydromechanical coupling equations; groundwater flow paths and ages are then solved for numerically using groundwater flow and advection-dispersion equations in a traditional Toth basin. Results suggest hydraulic conductivity alteration is dominated by fracture normal closure, resulting in decreasing hydraulic conductivity and increasing groundwater age with depth, and decreased depth of long flow paths with decreasing normal stiffness. Shear dilation has minimal effect on hydraulic conductivity alteration for stress states investigated here. Results are interpreted to suggest that fracture normal stiffness influences hydraulic conductivity of hydraulically active fractures and, thus, affects flow and transport in shallow (<1 km) fractured-rock aquifers. It is suggested that observed depth-dependent hydraulic conductivity trends in fractured-rock aquifers throughout the world may be partly a manifestation of hydromechanical phenomena. 相似文献
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Chin-Fu Tsang Jan-Erik Rosberg Prabhakar Sharma Theo Berthet Christopher Juhlin Auli Niemi 《Hydrogeology Journal》2016,24(6):1333-1341
Drilling of a deep borehole does not normally allow for hydrologic testing during the drilling period. It is only done when drilling experiences a large loss (or high return) of drilling fluid due to penetration of a large-transmissivity zone. The paper proposes the possibility of conducting flowing fluid electrical conductivity (FFEC) logging during the drilling period, with negligible impact on the drilling schedule, yet providing important information on depth locations of both high- and low-transmissivity zones and their hydraulic properties. The information can be used to guide downhole fluid sampling and post-drilling detailed testing of the borehole. The method has been applied to the drilling of a 2,500-m borehole at Åre, central Sweden, firstly when the drilling reached 1,600 m, and then when the drilling reached the target depth of 2,500 m. Results unveil eight hydraulically active zones from 300 m down to borehole bottom, with depths determined to within the order of a meter. Further, the first set of data allows the estimation of hydraulic transmissivity values of the six hydraulically conductive zones found from 300 to 1,600 m, which are very low and range over one order of magnitude. 相似文献
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在地下水扩散方程中,压力传导系数是描述地下水运动的重要参数。传统的方法是通过抽水或注水给地下水系统一个扰动,监测地下水水位的响应,由此计算含水层的压力传导系数。文章提出用潮汐衰减率方法识别含水层压力传导系数,其适用于滨海区承压含水层的参数识别。在推导出解析解的基础上,通过数值拟合、最小二乘法、牛顿迭代法求得含水层的压力传导系数,提出潮汐衰减率的概念,建立余切函数与潮汐衰减率的线性关系,用线性关系中的斜率和截距识别压力传导系数。用潮汐衰减率方法识别出的压力传导系数与其实际值相等,说明该方法是正确有效的。潮汐信号衰减率与海水振荡的余切函数线性相关。数值仿真表明,该方法可以准确地估算出含水层的压力传导系数。潮汐衰减率方法具有少打井,经济高效等优点。潮汐衰减率方法为实际工程应用提供了可靠的理论基础,它可以用于部分实际工程中。该方法的局限性在于需要提供含水层的部分参数,如含水层的长度、海水波动振幅、频率等。 相似文献
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Shouliang Huo Beidou Xi Jing Su Zhuoshi He Fengyu Zan Hong Yu 《Environmental Earth Sciences》2014,71(3):995-1005
Establishing reference conditions for regional lakes is necessary to assess human impact on aquatic ecosystems, protect water quality and biotic integrity. The northeast eco-region lakes often present a marked seasonal variability in hydrological, biological and geochemical processes, which could affect physico-chemical variables, chlorophyll-a and Secchi depth reference conditions. Reference conditions were calculated using two different methods: lake population distribution method and trisection method. General physico-chemical reference conditions (pH, conductivity, BOD and nutrients) and chlorophyll-a, and Secchi depth reference conditions were established using the two approaches combined with the analysis of seasonal variability for each parameter for shallow and deep lake types in the northeast eco-region lakes. The results indicated that depth was an important factor affecting physico-chemical variables, chlorophyll-a and Secchi depth reference values. Moreover, the seasonal differences in parameters were also assessed using a non-parametric repeated measure ANOVA (Friedman test) in the shallow and deep lakes. Some parameters showed a seasonal variability for shallow and deep lakes. The least restrictive reference values of the four seasons were proposed to simplify the water quality assessment for regional lake management goals. These results indicated that the 50th percentile (median) value from the best one-third of the nutrient-concentration data distributions is more appropriate for the northeast eco-region lakes. 相似文献
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Marcellus Shale Lithofacies Prediction by Multiclass Neural Network Classification in the Appalachian Basin 总被引:4,自引:0,他引:4
Marcellus Shale is a rapidly emerging shale-gas play in the Appalachian basin. An important component for successful shale-gas reservoir characterization is to determine lithofacies that are amenable to hydraulic fracture stimulation and contain significant organic-matter and gas concentration. Instead of using petrographic information and sedimentary structures, Marcellus Shale lithofacies are defined based on mineral composition and organic-matter richness using core and advanced pulsed neutron spectroscopy (PNS) logs, and developed artificial neural network (ANN) models to predict shale lithofacies with conventional logs across the Appalachian basin. As a multiclass classification problem, we employed decomposition technology of one-versus-the-rest in a single ANN and pairwise comparison method in a modular approach. The single ANN classifier is more suitable when the available sample number in the training dataset is small, while the modular ANN classifier performs better for larger datasets. The effectiveness of six widely used learning algorithms in training ANN (four gradient-based methods and two intelligent algorithms) is compared with results indicating that scaled conjugate gradient algorithms performs best for both single ANN and modular ANN classifiers. In place of using principal component analysis and stepwise discriminant analysis to determine inputs, eight variables based on typical approaches to petrophysical analysis of the conventional logs in unconventional reservoirs are derived. In order to reduce misclassification between widely different lithofacies (for example organic siliceous shale and gray mudstone), the error efficiency matrix (ERRE) is introduced to ANN during training and classification stage. The predicted shale lithofacies provides an opportunity to build a three-dimensional shale lithofacies model in sedimentary basins using an abundance of conventional wireline logs. Combined with reservoir pressure, maturity and natural fracture system, the three-dimensional shale lithofacies model is helpful for designing strategies for horizontal drilling and hydraulic fracture stimulation. 相似文献
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Water salinity at shallow sea depths in shelf areas changes with depth, which causes respective conductivity changes. We discuss algorithms for computing monochromatic electric fields using the vector finite-element method with different realizations of depth dependence of conductivity. The algorithms have been applied to compute vertical conductivity patterns and to explore its influence on the electric field measured on the surface. 相似文献