首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Wadi Zerka Ma’in catchment area is located to the north east of the Dead Sea. It has two types of aquifers: (a) an upper unconfined aquifer and (b) a lower confined aquifer. The two aquifers are separated by a marl aquiclude. A major strike slip fault passes perpendicularly through the two aquifers and the aquiclude layer with embedded normal faults. The aim of the study was to specify the effect of the major strike slip fault on the groundwater chemistry. The spatial variability of the hydrochemical compositions and physiochemical parameters of the groundwater were investigated. It was found that the embedded normal faults, of the strike slip fault, form conduits that allow groundwater to flow from the lower aquifer to the upper aquifer, resulting in mixed groundwater. The ratio of mixing was estimated to be 94 % groundwater from the upper aquifer and 6 % from the lower aquifer. Since groundwater in the lower aquifer is around three times more saline than the upper aquifer, water mixing into the upper water aquifer generates a salinity hazard.  相似文献   

2.
The present work deals with the groundwater aquifer of the Lower Cretaceous sandstone and its sustainable development in Sinai. The studied aquifer system is the most promising groundwater system in Sinai due to its wide extension, hug storage, and good quality. The objective of this paper aims to elucidate the hydrogeological characteristics of the Lower Cretaceous aquifer. The aquifer system occurs under confined conditions. The top surface of the Lower Cretaceous dips steeply towards the southwest direction with step faults. The average sand percent of the penetrated aquifer attains 54%. The main direction of groundwater flow is generally from southwest and locally is concentric to the center of study area related to the influence of the graben block. The aquifer has a hydraulic gradient generally reaches 0.0011 m/m and attains 0.0028 in central portion of study area. The aquifer parameters (effective porosity, transmissivity, and hydraulic conductivity) increase towards the northeast direction with increasing of the sand percentage. Durov diagram plot revealed that the groundwater has been a final stage evolution represented by a NaCl water type. The groundwater salinity increases towards the central of study area coinciding with groundwater flow. The groundwater salinity of the Lower Cretaceous aquifer is brackish water and varies from 2,510 to 5,256 ppm and unsuitable for drinking and domestic purposes.  相似文献   

3.
《地学前缘(英文版)》2020,11(4):1431-1440
The Mahanadi delta, deposited on a series of horst and graben basement structures, is considered an extension of the East Lambert Rift of Antarctica. Current study is based on the hydrogeochemical assessment of this deltaic aquifer system and geospatial analysis thereof, to appreciate the basement structure influence on groundwater chemistry. Major ion chemistry of subsurface waters portrays a distinct saline contamination across the terrain and varied regimes of water types, specifically with respect to southern and northern parts of this aquifer system. Findings of the study indicate a general near surface saline horizon and significant fragmentation of the hydrostatic units. This, in turn, implies noteworthy influence of formational water to salinity regimes and basin structural changes for the escape of these waters to surroundings. A plot of recent low intensity earthquakes displays proximity of epicenters to the faults as well as striking similarity to the trend of terrestrial faults indicating multiple reactivations of the faults. To further corroborate the above findings, spatial pattern analysis of individual hydrochemical variables is carried out which reveals specific clusters of sources (groundwater mixing) and sinks (groundwater dispersion) in proximity to basement fault dispositions. While the faults can be disregarded as conduits or barriers owing to their great depth, the overlying sedimentary mass, particularly, the horizons with significant clayey content have been distorted due to post rift subsidence and fault reactivations. A proximity analysis of ionic clusters points towards a greater influence of longitudinal faults to that of the transverse ones on groundwater mixing or dispersion.  相似文献   

4.
Seismic sections across the NW part of the Polish Basin show that thrust faults developed in the sedimentary units above the Zechstein evaporite layer during basin inversion. These cover thrust faults have formed above the basement footwall. Based on the evolution of the basin, a series of scaled analogue models was carried out to study interaction between a basement fault and cover sediments during basin extension and inversion. During model extension, a set of normal faults originated in the sand cover above the basement fault area. The distribution and geometry of these faults were dependent on the thickness of a ductile layer and pre-extension sand layer, synkinematic deposition, the amount of model extension, as well as on the presence of a ductile layer between the cover and basement. Footwall cover was faulted away from the basement only in cases where a large amount of model extension and hanging-wall subsidence were not balanced by synkinematic deposition. Model inversion reactivated major cover faults located above the basement fault tip as reverse faults, whereas other extensional faults were either rotated or activated only in their upper segments, evolving into sub-horizontal thrusts. New normal or reverse faults originated in the footwall cover in models which contained a very thin pre-extension sand layer above the ductile layer. This was also the case in the highly extended and shortened model in which synkinematic hanging-wall subsidence was not balanced by sand deposition during model extension. Model results show that inversion along the basement fault results in shortening of the cover units and formation of thrust faults. This scenario happens only when the cover units are decoupled from the basement by a ductile layer. Given this, we argue that the thrusts in the sedimentary infill of the Polish Basin, which are decoupled from the basement tectonics by Zechstein evaporites, developed due to the inversion of the basement faults during the Late Cretaceous-Early Tertiary.  相似文献   

5.
Groundwater in shallow unconsolidated sedimentary aquifers close to the Bornheim fault in the Lower Rhine Embayment (LRE), Germany, has relatively low δ2H and δ18O values in comparison to regional modern groundwater recharge, and 4He concentrations up to 1.7?×?10?4 cm3 (STP) g–1?±?2.2 % which is approximately four orders of magnitude higher than expected due to solubility equilibrium with the atmosphere. Groundwater age dating based on estimated in situ production and terrigenic flux of helium provides a groundwater residence time of ～107 years. Although fluid exchange between the deep basal aquifer system and the upper aquifer layers is generally impeded by confining clay layers and lignite, this study’s geochemical data suggest, for the first time, that deep circulating fluids penetrate shallow aquifers in the locality of fault zones, implying  that sub-vertical fluid flow occurs along faults in the LRE. However, large hydraulic-head gradients observed across many faults suggest that they act as barriers to lateral groundwater flow. Therefore, the geochemical data reported here also substantiate a conduit-barrier model of fault-zone hydrogeology in unconsolidated sedimentary deposits, as well as corroborating the concept that faults in unconsolidated aquifer systems can act as loci for hydraulic connectivity between deep and shallow aquifers. The implications of fluid flow along faults in sedimentary basins worldwide are far reaching and of particular concern for carbon capture and storage (CCS) programmes, impacts of deep shale gas recovery for shallow groundwater aquifers, and nuclear waste storage sites where fault zones could act as potential leakage pathways for hazardous fluids.  相似文献   

6.
Potassium chloride (KCl) and potassium bromide (KBr) tracers were used to explore the role of geologic structure on groundwater recharge and flow at the Fractured Rock Research Site in Floyd County, Virginia, USA. Tracer migration was monitored through soil, saprolite, and fractured crystalline bedrock for a period of 3 months with chemical, physical, and geophysical techniques. The tracers were applied at specific locations on the ground surface to directly test flow pathways in a shallow saprolite and deep fractured-rock aquifer. Tracer monitoring was accomplished with differential electrical resistivity, chemical sampling, and physical monitoring of water levels and spring discharge. KCl, applied at a concentration of 10,000 mg/L, traveled 160 m downgradient through the thrust fault aquifer to a spring outlet in 24 days. KBr, applied at a concentration of 5,000 mg/L, traveled 90 m downgradient through the saprolite aquifer in 19 days. Tracer breakthrough curves indicate diffuse flow through the saprolite aquifer and fracture flow through the crystalline thrust fault aquifer. Monitoring saline tracer migration through soil, saprolite, and fractured rock provided data on groundwater recharge that would not have been available using other traditional hydrologic methods. Travel times and flowpaths observed during this study support preferential groundwater recharge controlled by geologic structure.  相似文献   

7.
基于地震地质解释,根据断裂带发育的位置、产状及构造样式,将琼东南盆地深水区中央坳陷自西向东划分为3个断裂体系:乐东—陵水伸展南倾调节断裂体系、北礁—松南—宝岛伸展北倾调节断裂体系以及宝岛—长昌张扭走滑断裂体系。断裂体系控制了生烃凹陷的分布和储集砂体的发育,形成了多种类型的圈闭,提供了油气垂向运移的通道,有利于油气聚集成藏。陵水凹陷—北礁凹陷结合部圈闭发育带、宝岛凹陷南部断阶带、长昌凹陷西部圈闭发育带是有利勘探区带。  相似文献   

8.
High iron concentrations create water quality problems for municipal use in glacial drift aquifer units. The chemical evolution of oxic groundwater in shallow aquifer units to anoxic groundwater in deeper aquifer units, in which soluble Fe(II) is stable, is attributed to coupled reduction of Fe(III) on aquifer solids with oxidation of organic carbon. The objective of this study was to characterize the distribution of organic carbon in aquifer and aquitard sediments to determine the availability of potential electron donors to drive these reactions. To do this, four complete rotasonic cores in a glacial aquifer/aquitard system were sampled at close intervals for analyses of grain-size distribution and organic carbon content. The results indicate significantly higher organic carbon concentrations in diamicton (till) units that function as aquitards, relative to coarse-grained aquifer units. In addition, readily reducible iron content in the diamicton units and lower aquifer unit materials is sufficient to produce far more dissolved iron than is present in the aquifer. Groundwater evolves to the level of iron reduction as a terminal electron-accepting process as it moves downward through aquitard units along flow paths from upland recharge areas to downgradient discharge areas. Deeper aquifer units are therefore unlikely to contain groundwater with low iron concentration.  相似文献   

9.
Complex flow circulation patterns are likely to be present in fault‐controlled groundwater flow systems, such as carbonate aquifers. Nevertheless, not much information is available for faults in carbonates, and their hydrogeological behaviour is often neglected in conceptual and numerical models. The understanding of this aspect of subsurface fluid flow has been improved in a carbonate aquifer, where hydrogeological investigations at site scale demonstrated the existence of fault zones that act as barriers. The hydraulic conductivity of the fault core is as low as that of siliciclastic rocks that represent the regional aquitard of the carbonate aquifer. Despite the lower permeability, the fault zones allow a significant groundwater flowthrough and a good interdependence of piezometric heads upgradient and downgradient of the faults. Because of this discontinuous heterogeneity, the aquifer looks like a basins‐in‐series system, where seasonal springs can be detected along some fault zones, as a function of groundwater level fluctuations.  相似文献   

10.
根据现代油气成藏理论,从分析原油成因和油气分布规律出发,结合油源对比结果,对高邮凹陷马家嘴地区油气差 异性分布的影响因素进行了分析。结果表明：马家嘴地区以断层－岩性油藏为主,主要沿真②断层和汉留断层分布有两类 原油,均来自异地的邵伯次洼阜四段烃源岩,油气充注期都为始新世中、晚期;原油类型分带分布并非是不同源或同源不 同运移期所致,而主要为运移路径不同所致;真②断层和汉留断层控制了油气主运移通道,且前者输导油气能力较强,造 成了沿真②断层分布的油藏成熟度整体低于沿汉留断层分布的油藏;在沉积微相的控制作用下,离断层稍远的物性较好的 扇中和扇端的含油性普遍好于靠近断层的物性较差的扇根;断层产状、砂体尖灭方向和地层走向的配置关系决定了断层－ 岩性油藏的充满度。  相似文献   

11.
The aquifer of early Cretaceous age in the Meskala region of the Essaouira Basin is defined by interpretation of geological drilling data of oil and hydrogeological wells, field measurement and analysis of in situ fracture orientations, and the application of a morphostructural method to identify lineaments. These analyzes are used to develop a stratigraphic–structural model of the aquifer delimited by fault zones of two principal orientations: NNE and WNW. These fault zones define fault blocks that range in area from 4 to 150 km2. These blocks correspond either to elevated zones (horsts) or depressed zones (grabens). This structural setting with faults blocks of Meskala region is in accordance with the structure of the whole Essaouira Basin. Fault zones disrupt the continuity of the aquifer throughout the study area, create recharge and discharge zones, and create dip to the units from approximately 10° to near vertical in various orientations. Fracture measurements and morphometric-lineament analyzes help to identify unmapped faults, and represent features important to groundwater hydraulics and water quality within fault blocks. The above geologic features will enable a better understanding of the behaviour and hydro-geo-chemical and hydrodynamics of groundwater in the Meskala aquifer.  相似文献   

12.
Faults in continental flood basalt sequences potentially control subsurface fluid flow. We present field and microstructural observations from fault zones cutting interlayered basaltic volcaniclastic-crystalline sequences within the North Atlantic Igneous Province. Fractures likely initiate within lava units, before linking through the volcaniclastic units. Through-going faults show refraction, with subvertical faults in the lavas joined to variably inclined faults in the volcaniclastic layers. At >1.0 m displacement, volcaniclastic units are progressively dragged into the fault plane forming a smear. Volcaniclastic sandstones deform by flow. Claystones fracture, and are incorporated into smears as breccia. Experimentally measured host and fault rock sample permeabilities, at aquifer to reservoir pressures (i.e., 10–90 MPa; ∼0.3–3.0 km depth) show fault rocks from low displacement faults have relatively low permeability (10−17–10−20 m2); fault rocks from higher displacement structures have comparatively high permeability (10−15–10−17 m2). Our observations suggest that permeability is determined by the opposing influences of clay mineralization, which decreases permeability, versus the development of interconnected, higher permeability zeolite veins. Brecciation and the formation of zeolite vein networks within claystone smears results in high permeability. Zeolite veins in volcaniclastic units form poorly-connected, spaced sets, parallel to the slip plane, hence sequence permeability remains low.  相似文献   

13.
库车坳陷的断裂有效运移通道及其物理模拟   总被引：3，自引：3，他引：0       下载免费PDF全文
库车坳陷区的变形,垂向上可分为3大构造层:盐上层、新生代膏盐层和盐下层。根据该地典型构造的含气性差异,分析了断裂有效输导天然气的地质条件,认为充足且有效的气源条件、沟通源岩与圈闭且不断穿区域性盖层的盐下断裂以及完整的圈闭是决定天然气沿断裂运聚成藏的重要条件,因而不断穿区域性盖层的盐下断裂是有效油气运移通道,并用物理模拟对其进行了验证。通过分析与断裂有效运移通道相配置的砂体的封闭程度、体积和物理性质的差异发现:沿断裂有效运移通道运移的天然气向断裂两侧储层分流的优势运移路径明显不同,在发育断裂有效运移通道时,断裂带内部的流体总是向着断裂带两侧封闭程度差、体积大和物性好的储层分流运移。  相似文献   

14.
The Beypazari region in NW Anatolia (Turkey) is characterized by high water demand and stress on available water resources. Tectonic structures control the groundwater flow, hydraulic head and well yield in the study area, which is located in the central part of the Beypazari Neogen basin. The impact of major tectonic structures on groundwater flow in the Cakiloba-Karadoruk aquifer is described. This aquifer is of sedimentary composition and underwent tectonic deformation, post-Miocene, forming northeast-striking asymmetric synclines, anticlines, monoclines, high-angle reverse faults and N–S striking tensional faults. Some of these structures affect groundwater flow by separating the aquifer system into sub-compartments, each having unique recharge, boundary and flow conditions. The groundwater system is compartmentalized into three sub-systems under the impacts of the Zaviye and Kanliceviz faults: (1) Arisekisi, (2) Elmabeli and (3) Southern sub-systems. The southern part of the Arisekisi sub-system and the Southern sub-system are characterized by a syncline and the aquifer is confined in the central part of the syncline. The Elmabeli sub-system has unconfined conditions. Consequently, the effects of tectonic structures are shown to be important for selecting well locations, evaluating groundwater use, groundwater management, and contaminant control in the study area, and also in other tectonic regions.  相似文献   

15.
The impact of inclined faults on the hydrothermal field is assessed by adding simplified structural settings to synthetic models. This study is innovative in carrying out numerical simulations because it integrates the real 3-D nature of flow influenced by a fault in a porous medium, thereby providing a useful tool for complex geothermal modelling. The 3-D simulations for the coupled fluid flow and heat transport processes are based on the finite element method. In the model, one geological layer is dissected by a dipping fault. Sensitivity analyses are conducted to quantify the effects of the fault’s transmissivity on the fluid flow and thermal field. Different fault models are compared with a model where no fault is present to evaluate the effect of varying fault transmissivity. The results show that faults have a significant impact on the hydrothermal field. Varying either the fault zone width or the fault permeability will result in relevant differences in the pressure, velocity and temperature field. A linear relationship between fault zone width and fluid velocity is found, indicating that velocities increase with decreasing widths. The faults act as preferential pathways for advective heat transport in case of highly transmissive faults, whereas almost no fluid may be transported through poorly transmissive faults.  相似文献   

16.
油气储层流动单元在高、中、低渗储层表征中已经得到普遍应用,但在特低渗储层研究中仍然很少涉及.以松辽盆地北部三肇凹陷升554断块下白垩统泉头组四段扶余油层特低渗储层为例,划分出E、G、P三种流动单元类型,从E类至P类流动单元,渗流能力逐渐减小.流动单元物性特征、空间分布特征均表明流动单元储层非均质性较强.分析了沉积相及开...  相似文献   

17.
河南木厂河地区,位于秦岭-大别山中央造山带的东部,桐柏-大别构造亚带东段。区内以长期活动的NWW-近EW向深大断裂及派生的NWW向,SN向断裂以及平行于东部郯庐断裂带的NE向断裂为主要特征,褶皱表现为形态复杂的宽缓线形。通过调查研究,确认了木厂河矿区存在三个构造岩石单元:核杂岩单元(CC)、超高压单元(UHP)、高压单元(HP).各单元之间发育有大型的拆离断层,有利于成矿元素富集。本区矿床的形成与大别山超高压变质带折返后的伸展拆离作用密切相关。矿体形成部位主要在核杂岩单元之上,超高压单元之下的拆离断层带。拆离断层对本区的矿化起了重要的控制作用。   相似文献   

18.
断层输导作用与油气充注作用关系分析   总被引：2，自引：0，他引：2       下载免费PDF全文
刘震  张旺  曹尚  刘明洁  张威  董冬 《地质科学》2014,49(4):1302-1313
断层是控制油气藏形成的重要因素之一;断层的开启及闭合影响到油气运移与聚集的效率。但油气在断层中的运移与在砂层中的充注存在差异性这一问题长期被忽视。一般认为;只要发育断层;其断开的渗透层就会被油气充注;极少关注地层水和石油的压缩特性对充注的影响。本文提出;地下单断层活动时;深部油气在超压作用下以涌流方式难以快速充注进入中浅层被切割的砂体;因此;单砂体至少要存在一条断层作为泄水出口;石油才能通过其余断层充注进入砂体;即单砂体要发育两条及两条以上断层;石油才能注入砂体。在断层静止期;油气通过渗流方式沿特定深度范围断面垂向运移;对油气垂向运移距离影响较小。本文运用4个大型盆地的典型油气藏与断层分布关系讨论了本文观点。该观点对油气成藏规律研究及成藏目标评价有较重要参考意义。  相似文献   

19.
Hydrogeologically, faults may impede, conduit, exert no influence, or may play a combination of these roles on groundwater flow. The object of this paper is to study the hydrogeological role of the Tabarteh fault, which is located on the border of Zagros and Central Iran tectonic zones in an alluvial aquifer. The recorded data of water table levels, chemical parameters, and discharge rate of wells, in addition to geological maps and geophysical results, were collected and evaluated. The outcrop of travertine in limited areas and the emergence of a few small springs within the alluvium show a barrier role of the fault in the groundwater flow. The spatial analysis of chemical components, head time series, and groundwater flow direction assessment demonstrated that the fault acts as both a barrier and a non-barrier in different sections. The multivariate statistical methods of cluster and discriminant analyses also confirm the dual role of the fault.  相似文献   

20.
Three dimensional lithologic modeling techniques have been used for detailed characterization and groundwater flow modeling of the Quaternary aquifer system of the Sohag area, Egypt. Well log data were used for building the lithologic model using RockWorks. A groundwater flow model, facilitated by MODFLOW 2000, was built using results of the lithologic model. The obtained lithologic model honored the well log data and revealed a complex sedimentary system, which is mainly composed of six lithologic categories: clay, clay and sand, fine sand, coarse sand, sand and gravel, and gravel. Inter-fingering and presence of lenses are the main characteristics of the sedimentary basin in the study area. A wide range of hydraulic conductivities is present, which vary spatially and control the groundwater flow. Heterogeneity of the aquifer system is spatially represented where different hydraulic conductivities are found in the different directions. Sandy layers tend to be connected. Hydraulic continuity is represented by inter-fingering and connection of sandy materials within the aquifer system.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号