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.
The Kangan aquifer (KA) is located beneath the Kangan gas reservoir (KGR), 2,885 m below the ground surface. The gas reservoir formations are classified into nine non-gas reservoir units and eight gas reservoir units based on the porosity, water and gas saturation, lithology, and gas production potential using the logs of 36 production wells. The gas reservoir units are composed of limestone and dolomite, whereas the non-gas reservoir units consist of compacted limestone and dolomite, gypsum and shale. The lithology of KA is the same as KGR with a total dissolved solid of 333,000 mg/l. The source of aquifer water is evaporated seawater. The static pressure on the Gas–Water Contact (GWC) was 244 atm before gas production, but it has continuously decreased during 15 years of gas production, resulting in a 50 m uprising of the GWC and the expansion of KA water and intergranular water inside the gas reservoir. The general flow direction of the KA is toward the northern coast of the Persian Gulf due to the migration of water to the overlying formations via a trust fault. The KA is a gas-capped deep confined aquifer (GCDCA) with special characteristics differing from a shallow confined aquifer. The main characteristics of a GCDCA are unsaturated intergranular water below the confining layers, no direct contact of the water table (GWC) with the confining layers, no vertical flow via the cap rock, permanent uprising of the GWC during gas production, and permanent descend of GWC during water exploitation.  相似文献   

2.
The Kangan Permo-Triassic brine aquifer and the overlying gas reservoir in the southern Iran are located in Kangan and Dalan Formations, consisting dominantly of limestone, dolomite, and to a lesser extent, shale and anhydrite. The gasfield, 2,900 m in depth and is exploited by 36 wells, some of which produce high salinity water. The produced water gradually changed from fresh to saline, causing severe corrosion in the pipelines and well head facilities. The present research aims to identify the origin of this saline water (brine), as a vital step to manage saline water issues. The major and minor ions, as well as δ2H, δ18O and δ37Cl isotopes were measured in the Kangan aquifer water and/or the saline produced waters. The potential processes causing salinity can be halite dissolution, membrane filtration, and evaporation of water. The potential sources of water may be meteoric, present or paleo-seawater. The Na/Cl and I/Cl ratios versus Cl? concentration preclude halite dissolution. Concentrations of Cl, Na, and total dissolved solid were compared with Br concentration, indicating that the evaporated ancient seawater trapped in the structure is the cause of salinization. δ18O isotope enrichment in the Kangan aquifer water is due to both seawater evaporation and interaction with carbonate rocks. The δ37Cl isotope content also supports the idea of evaporated ancient seawater as the origin of salinity. Membrane filtration is rejected as a possible source of salinity based on the hydrochemistry data, the δ18O value, and incapability of this process to dramatically enhance salinity up to the observed value of 330,000 mg/L. The overlaying impermeable formations, high pressure in the gas reservoir, and the presence of a cap rock above the Kangan gasfield, all prevent the downward flow of meteoric and Persian Gulf waters into the Kangan aquifer. The evaporated ancient seawater is autochthonous, because the Kangan brine aquifer was formed by entrapment of brine seawater during the deposition of carbonates, gypsum, and minor clastic rocks in a lagoon and sabkha environment. The reliability of determining the source of salinity in a deep complicated inaccessible high-pressure aquifer can be improved by combining various methods of hydrochemistry, isotope, hydrodynamics, hydrogeology and geological settings.  相似文献   

3.
The Upper Permian Dalan Formation and the Lower Triassic Kangan Formation in the Persian Gulf area are mainly composed of shallow marine facies limestone and dolomite. Two subsurface-cored intervals were investigated in order to understand the original mineralogy and paleoceanic conditions. The decreasing trend of Sr concentration in these deposits shows that aragonite was precipitated during the Late Permian and then gradually changed to calcite toward the Permian–Triassic boundary (PTB). The dissolution rate of aragonite decreased from 60 m below the PTB toward the boundary, with the only exception at 10 m below the Permian-Triassic Boundary (PTB) due to the Permian–Triassic unconformity in this region. The increasing trend of Mg/Ca ratio in a global scale at the end-Permian time shows that the interpreted variation of mineralogy does not result from the change of this ratio. The increasing pCO2 and decreasing pH are considered to be the main controlling factors. The increase of Ca2+ at the end-Permian time due to the input of meteoric waters is too little to fully compensate this effect. A local maximum of the Si content just at the PTB confirms the input of runoff waters.  相似文献   

4.
Geomechanics is a science dealing with the study of the behaviour of rocks affected by stress. It has various applications in utilisation from oil and gas reservoirs including of the wellbore stability analysis and determination of safe mud window. The main aim of this paper is geomechanical study of Kangan–Dalan reservoir in South Pars gas field in Persian Gulf in south Iran. Seismic waves are affected by physical properties of rocks when passing underground formations; thus, the velocity of these waves is a desired parameter for estimation of geomechanical properties. The velocity of compressional and shear waves has been determined with processing seismic data resulting from vertical seismic profile. In this paper, after calculation of elastic modules of reservoir rock, the imposed stress field was determined and these concepts were used for engineering calculations such as safe mud window, wellbore stability analysis and sand production potential. For well drilling in Kangan-Dalan reservoir, the minimum and maximum mud weights were proposed in average as 1.093 and 2.011 gr/cc and average critical mud weight as 2.48 gr/cc such that if the weight of mud increases, the tensile fractures will be created on the formation and complete loss of mud will happen.  相似文献   

5.
北部湾东部海域表层沉积物稀土元素组成及物源指示意义   总被引：8，自引：0，他引：8  
窦衍光  李军  李炎 《地球化学》2012,(2):147-157
对北部湾东部海域70个表层沉积物样品的稀土元素(REE)分析结果表明,研究区沉积物 REE 呈现轻稀土元素(LREE)富集、重稀土元素(HREE)平坦以及中等程度的 Eu 异常等特征.REE 组成受沉积物粒度和生物碳酸盐含量的制约,具有典型风化上陆壳 REE 特征,其源岩以上陆壳的长英质岩石为主.根据研究区沉积物 REE 分布规律,研究区可划分为4个地球化学分区,各区域上陆壳标准化曲线明显的不同.物源判别显示研究区的西部、海南岛西南侧(Ⅰ区)呈多源沉积特征,来自以下几个物源区:(1)海南岛西南侧河流沉积物和沿岸侵蚀物;(2)由南向北输入的外海沉积物(冬季);(3)夏季或冬季由北部湾西北部和西部搬运来的沉积物.研究区中部粗粒沉积区(Ⅱ区)与北部湾西部沉积物来源是相同的,主要来源于红河输砂.东北部砂质区(Ⅲ区)沉积物可能来源于雷州半岛西北部近岸基岩侵蚀.研究区东北部(Ⅳ区)沉积物主要来自北部湾北部沿岸侵蚀、琼州海峡和雷州半岛西部的沿岸侵蚀.此外,部分沉积物还可能来自珠江流域以及南海北部陆架区和北部湾西北部  相似文献   

6.
The southern coastal plain of Iran at the Persian Gulf encounters oil pollution due to the historical oil exploitation, related tanker navigations and accidents, and petrochemical industrial expansions in the recent years. Therefore, it is important to investigate the geochemical properties of oil-contaminated coastal soils and sediments for engineering and environmental purposes. Here, an extensive laboratory testing program was carried out to determine the effects of crude oil contamination on some of the geotechnical properties of clayey and sandy soils such as CL, SM and SP sampled from the coastal soils from this area. The testing included basic properties, Atterberg limits, compaction, direct shear, uniaxial compression and permeability tests on clean and contaminated soil samples at the same densities. The contaminated samples were prepared by mixing the soils with crude oil in the amount of 2%, 4%, 8%, 12%, and 16% by dry weight. The results indicated a decrease in strength, permeability, maximum dry density, optimum water content and Atterberg limits. Knowledge of these effects of oil contamination is important in coastal engineering and environmental remediation activities of the studied coastal plain.  相似文献   

7.
The major and trace element distribution was studied in the Eocene-Miocene stratotype section of the northern Aral region, northern coast of the Perovskii Gulf. The geochemical specific of ore-bearing rocks is shown. Qualitative trends in the distribution of element in genetically diverse rocks are established.  相似文献   

8.
The main semidiurnal (M2 and S2) and diurnal (K1 and O1) tidal constituents are simulated in the Persian Gulf (PG). The topography is discretized on a spherical grid with a resolution of 30 s in both latitude and longitude. It includes coastal areas prone to flooding. The model permits flooding of drying banks up to 5 m above mean sea level. At the open boundary, it is forced by 13 harmonic constituents extracted from a global tidal model. The model results are in good agreement with tide gauge observations. Co-tidal charts and flow extremes are presented for each tidal constituent. The co-tidal charts show two amphidromic points for semidiurnal and one for diurnal tidal constituents. Maximum amplitudes of sea level are obtained for the north-western part of the PG, where coastal flooding prevails in wide areas. Strong tidal currents occur in different parts of the PG for different types of constituents. Maximum velocities are found in shallow regions. Particularly, high amplitudes of elevations and high speed currents are founded in the canal between Qeshm Island and the mainland. Rectification of tides around Qeshm Island affects the propagation of tides in the PG as far as the coast of Saudi Arabia and the northern part of the PG.  相似文献   

9.
The Lower Triassic Kangan Formation in the Persian Gulf (South Pars Gas Field) and its adjacent areas are composed of carbonate–evaporite sequences. These sediments were deposited in a shallow marine homoclinal ramp. Study of the anhydrite-bearing intervals shows various structures and textures. The anhydrite structures are mainly bedded, massive, chicken-wire and nodular type and the main textures are felted, sparse crystal, needle shape, lath shape, equant and fibrous. Pervasive and poikilotopic cement together with replacement and porphyroblastic gypsum are accounted as the most common diagenetic features in anhydrite. Evaluation of anhydrite occurrences and features support both primary and secondary formations. The nodular to chicken-wire anhydrite formed under synsedimentary sabkha conditions, whereas anhydrite cements occurred during the late stages of diagenesis (shallow burial stage). Massive to bedded anhydrite could have been formed under subaqueous conditions or originated by coalescing and continued growth of anhydrite nodules in the sabkha zone. Anhydrite fabrics impose a significant control on the reservoir quality of the Kangan carbonates at the South Pars Gas Field. Thick massive and bedded anhydrite could have been formed as an intraformational seals and anhydrite cements occluded pore spaces and reduced the poroperm values. The sequence stratigraphic analysis revealed two depositional sequences in the studied intervals, which are composed of TST and HST. Investigation of anhydrite throughout depositional sequences indicates a change in the content and style of anhydrite texture. Anhydrite content (volume) decreases upward through transgressive system tract (sea-level rise) whereas, it enhances during highstand system tract (sea-level fall). Pervasive and poikilotopic anhydrite cements together with replacement by anhydrite are prevalent features during transgressive and early highstand system tract. At the late HST, with a progradational stacking pattern, anhydrite value increases and felted, radial, equant, crystalline and mosaic texture are the most common anhydrite fabrics. Sequence boundaries that indicate maximum sea level fall and exposure of successions are marked by the broad anhydrite deposits with massive to bedded and chicken-wire structures and various textures that located in late HST package. There is an unambiguous relationship between the microfacies associations, the evaporite textures, and the sea-level fluctuations. This relationship could lead to a predictable pattern that can be of use as a general guide for the sequence stratigraphic interpretations in the area.  相似文献   

10.
De Lange  W. P.  Healy  T. R. 《Natural Hazards》2001,24(3):267-284
The Hauraki Gulf is a semi-enclosed sea next to the largest population centre in New Zealand, the Auckland metropolitan region. The potential tsunami hazard is of concern to regional and local planners around the Hauraki Gulf. The Hauraki Gulf has recorded 11 tsunamis and one meteorological tsunami (rissaga) since 1840.The historical tsunami data are relatively sparse, particularly for the largest events in 1868 and 1883. Moreover, local sources may produce damaging tsunamis but none has occurred during recorded history. Therefore numerical modelling of potential tsunami events provides a powerful tool to obtain data for planning purposes. Three main scenarios have been identified for numerical modelling:1. A teletsunami event from an earthquake off the West Coast of South America. Historically this region has produced the largest teletsunamis in the Hauraki Gulf.2. A tsunami generated by a local earthquake along the Kerepehi Fault. This fault bisects the Gulf, has been active during the last century at the southern inland end, and is overlain by a considerable thickness of soft sediment that may amplify the seismic waves.3. A tsunami generated by a volcanic eruption within the Auckland Volcanic Field. This field has involved a series of mainly monogenetic basaltic eruptions over the last 140,000 years. Many of these eruptions have involved phreatomagmatic eruptions around the coastal margins, or within the shallow waters close to Auckland.  相似文献   

11.
The geochemical processes controlling chemical composition of groundwater are studied using hydrochemical and isotopic data in Abdan-Dayer coastal plain, south of Iran. The salinity of groundwater in the coastal plain ranges from 1,000, a fresh end-member, to more than 50,000 μS cm?1, a saline end-member. Groundwater salinity increases from the recharge area toward areas with a shallow water table close to the Persian Gulf coast due to direct evaporation and sea water intrusion as confirmed by mixing binary diagrams, stable isotope content, and Br?/Cl? ratio. Groundwater flow pattern in the study area has been modified due to over-pumping of groundwater in recent years which resulted in further saline water migration toward fresh water and their mixing. The maximum mixing ratio is estimated about 15% in different parts of the study area according to chloride concentration.  相似文献   

12.
Ostracods from 14 surface sediment samples taken from the northwest part of the Persian Gulf (Iranian side) at water depths of 32-54 m were studied to evaluate the environmental pollution caused by oil spills following the 1991 Gulf War. With the exception of two live ostracods, which show no response to the contamination, at least 58 closed carapaces from 18 taxa of herbivorous and sediment-feeding species were found containing dark brown oil. All contaminated specimens were restricted to the uppermost part of the sediments (0.0-0.5 cm). The extent of the impact and the number of affected species varies within the samples. The most heavily contaminated ostracods were encountered in samples 1, 3, 14, 21 and 26 in which 3-5% of the complete carapaces contain oil residues. Compared to a previous sampling in 1965, seven additional ostracod species occur in the modern Persian Gulf. This indicates an intact environmental state prior to the Gulf War.  相似文献   

13.
The northern coasts of the Gulf of Mexico (GoM) are highly vulnerable to the direct threats of climate change, such as hurricane-induced storm surge, and such risks are exacerbated by land subsidence and global sea-level rise. This paper presents an application of a coastal storm surge model to study the coastal inundation process induced by tide and storm surge, and its response to the effects of land subsidence and sea-level rise in the northern Gulf coast. The unstructured-grid finite-volume coastal ocean model was used to simulate tides and hurricane-induced storm surges in the GoM. Simulated distributions of co-amplitude and co-phase lines for semi-diurnal and diurnal tides are in good agreement with previous modeling studies. The storm surges induced by four historical hurricanes (Rita, Katrina, Ivan, and Dolly) were simulated and compared to observed water levels at National Oceanic and Atmospheric Administration tide stations. Effects of coastal subsidence and future global sea-level rise on coastal inundation in the Louisiana coast were evaluated using a “change of inundation depth” parameter through sensitivity simulations that were based on a projected future subsidence scenario and 1-m global sea-level rise by the end of the century. Model results suggested that hurricane-induced storm surge height and coastal inundation could be exacerbated by future global sea-level rise and subsidence, and that responses of storm surge and coastal inundation to the effects of sea-level rise and subsidence are highly nonlinear and vary on temporal and spatial scales.  相似文献   

14.
Gemsa has been chosen as the site for one of a new generation of power stations along the south-western margin of the Gulf of Suez. This site has been affected by a number of destructive earthquakes (Mw> 5), in addition to large number of earthquakes with magnitudes of less than 5. In this study seismic activities in the region were collected and re-evaluated, and the main earthquake prone zones were identified. It is indicated that this site is affected by the southern Gulf of Suez, northern Red Sea and Gulf of Aqaba source zones. The southern Gulf of Suez source zone is the nearest to the proposed site. The stochastic simulation method has been applied to estimate the Peak GroundAcceleration at the site of the proposed Gemsa power plant. It was noticed that the pseudo-spectral acceleration (PSA) reaches 175 cm/sec2 resulting from the southern Gulf of Suez seismic source. In addition, the response spectrum was conducted with a damping value of 5% of the critical damping, and the predominant period reached 0.1sec at the site. These results should be taken into consideration by civil engineers and decision-makers for designing earthquake resistant structures.  相似文献   

15.
波斯湾地区面积仅占世界大陆与大陆架总面积的1.85%.为何却集中了迄今所知的世界油藏的一半以上?本文以历史因果论大地构造学的观点为基础。分析了波斯湾地区成油的大地构造背景.认识到该区为一有利于油气生成的波斯型地洼区.并通过对该种类型地洼区演化特征与油气形成关系的研究,认为该区油气田的时空分布受两个地洼区的演化和构造热动力事件控制.指出该区油气形成是因为具有丰富的生油物质,良好的生、储、盖组合,巨大的圈闭储集构造,合适的成油构造热动力.高效的运移作用和恰当的构造保存条件,并由于这些最佳的生、储、盖、圈、运、保条件集于一区的结果,而使本区成为世界石油之冠。  相似文献   

16.
During two distinct earthquakes occurred on March 7, 1867 and October 6, 1944, tsunami waves were also observed at some localities around the Gulf of Edremit, NE Aegean Sea. The first event (M w = 6.8) mostly affected the city of Mitilini of Lesvos Island while the Gulf of Edremit-Ayvacık earthquake (M S = 6.8) largely affected the northern and eastern coastal areas of the Gulf of Edremit. In 1944 earthquake, numerous surface cracks and water gushes were reported. The coastal neighborhoods of the town of Ayvalık in the east were flooded by tsunami waves. At the WSW extend of the main fault observed on land, which is parallel to the present-day slip vectors, some normal-oblique faults were observed close and subparallel to the northern coast. On the basis of historical documents, reports, interviews, geological setting, field observations and marine seismic reflection data, the 1944 earthquake was not triggered by one of the main fault segments but by a secondary fault or fault group which was described in this study. Depending on the distribution of tensional and compressional forces in the region, which rotates clockwise under the control of the middle strand of the North Anatolian fault, secondary fault groups become important. The moment tensor parameters of such small-size events have been determined and have obtained consistent results with the faults proposed in this study.  相似文献   

17.
The Queen City Formation (Eocene) displays an array of tide-dominated coastal facies in the Tyler Basin of the northern Gulf of Mexico. This facies assemblage, which is atypical of the microtidal, wave-dominated, coastal depositional complexes that characterize the Cenozoic Gulf basin, reflects tidal amplification in a generally protected embayment on the east flank of a strongly prograded delta system. The shallow embayment was confined to the east by contemporaneous uplift and shoaling across the Sabine Uplift. Fluvial, barrier (including ebb tidal delta), heterolithic tidal, estuary-fill, and tidal point-bar facies are all found at outcrop. These facies were projected into the three-dimensional geometry of the tide-dominated depositional complex. Inlet, estuary, and distributary-fill sand bodies, which are linear and diporientated, dominate lithofacies maps. The Queen City facies assemblage in the Tyler Basin records a mixture of mesotidal to macrotidal environments that were interspersed in time and space with fluvial-dominated lobes, which periodically prograded eastward from the deltaic depocentre into the flanking embayment. Queen City deposition terminated with regional marine flooding and deposition of glauconitic, fossiliferous shelf sands and muds of the Weches Formation. Transgression is marked by a prominent ravinement surface that truncates underlying facies of the tide-dominated shore zone.  相似文献   

18.
In this paper, simulation of oil spill due to tidal currents in Persian Gulf is performed by coupled solution of the hydrodynamics equations and an equation for convection and diffusion of the oil. The hydrodynamic equations utilized in this work consist of depth average equations of continuity and motion in two dimensional horizontal planes. The effect of evaporation is considered in the continuity equation and the effects of bed slope and friction, as well as the Coriolis effects are considered in two equations of motion. The overlapping cell vertex finite volume method is applied for solving the governing equations on triangular unstructured meshes. Using unstructured meshes provides great flexibility for modeling the flow in arbitrary and complex geometries, such as Persian Gulf flow domain. The results of the hydrodynamic model for tidal currents in Persian Gulf domain is examined by imposing tidal fluctuations to the main flow boundary during a limited period of time. Finally, the developed model is used to simulate an accidental oil spill from a point in Persian Gulf.  相似文献   

19.
Wetland ecosystems are particularly vulnerable due to flow of nutrients from the surrounding watershed. The study was performed in the Shadegan wetland, a Ramsar-listed wetland located in the south-west of Iran at the head of the Persian Gulf. The wetland plays a significant hydrological and ecological role in the natural functioning of the northern Gulf. The proposed wetland has different water quality characteristics in wet and dry years of study during 1994–2006. To determine the variables, sampling was carried seasonally for each year at six stations. The results indicate that wetland in wet years had high concentrations of nitrate and silicate, leading to oligo–meso eutrophic conditions. Wetland in dry years had high phosphate concentrations, resulting in meso-eutrophic conditions. Forcing functions, such as climatic patterns, water residence time, reduce runoff and increasing density of wastewaters from the surrounding urban, agricultural and industrial area are probably the main variables that explain the observed patterns.  相似文献   

20.
Since coastal tourism is one of the fastest growing sectors of tourism industry, coastal areas have become increasingly vulnerable in the case of flooding. While in recent years a number of different methods have been put forward to map coastal flood risks, the implications of tourism dynamics for the assessment of human casualties has remained largely overlooked in these models. This chapter examines to what extent the ignorance of (residential) coastal tourism may bias the calculations of human casualties. To this end, a case study has been conducted on the Belgian coast. Both the dynamic nature of coastal tourism and the behaviour of residential tourists in storm surge scenarios are considered. The results of this study show that including tourism dynamics in flood risk management is justified and appropriate, depending on the tourist attractiveness of the flood-prone area and its temporal fluctuations.  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