共查询到20条相似文献，搜索用时 15 毫秒
1.
Abdul S. Abdul 《Ground Water Monitoring & Remediation》1988,8(4):73-73
Laboratory column experiments were carried out to study the migration of petroleum products through a sandy porous medium. It was found that the oil pressure needed to displace water from the pores of the sand medium increased with depth below the top of the column. While oil under negative pressure displaced water through the variably unsaturated zone, a significant vertical column of oil was needed to displace water from the pores at the water table. These results indicate that oil penetration to and below the water table will occur only if the porous medium is highly conductive and the rate of oil leak is high. For small to moderate leak rates and hydraulic conductivities, oil would preferentially spread laterally through the zones above the water table. This process of spreading could serve as a natural barrier to severe aquifer contamination by petroleum products.
A simplified procedure was developed to give an order-of-magnitude estimate of the preferred subsurface migration pathways of leaked petroleum products. This procedure utilizes the main drainage and wetting curves for oil and water and the interfacial pressure between these two fluids. This approach could be useful in guiding exploratory investigations, reducing both the risk for further spreading of the contaminants and the investigative cost. 相似文献
A simplified procedure was developed to give an order-of-magnitude estimate of the preferred subsurface migration pathways of leaked petroleum products. This procedure utilizes the main drainage and wetting curves for oil and water and the interfacial pressure between these two fluids. This approach could be useful in guiding exploratory investigations, reducing both the risk for further spreading of the contaminants and the investigative cost. 相似文献
2.
Abdul S. Abdul Sheila F. Kia Thomas L. Gibson 《Ground Water Monitoring & Remediation》1989,9(2):90-99
Theoretical analysis and laboratory column experiments were carried out to investigate the conditions required for petroleum products (oil) to flow into a well installed through a sandy porous medium contaminated with the oil. The results indicated that oil would flow into a well only after a layer of "free oil" is formed in the adjacent porous medium. Because significant quantities of oil could be stored in the porous medium under the influence of capillary suction prior to the formation of the zone of free oil, the presence of oil in a well would indicate an advanced stage of oil contamination of the subsurface. While monitoring wells could be used to delineate the extent of the free-oil plume and the plume of dissolved petroleum constituents, they are not useful for delineating the extent of capillary held oil.
The experimental results also indicated that the ratio of the oil-layer thickness in the well to that in the porous medium is not a constant as is sometimes assumed in practice. Further, estimates of the oil thickness in the medium based on the oil thickness in wells and on capillary properties measured in the laboratory were sensitive to the values of the parameters used in these estimates. The measured thickness of the oil layer in a monitoring well alone may not yield reliable estimates of the amount of oil in the subsurface, and assuming that the oil-thickness ratio is a constant can lead to inadequate site assessments and inappropriate remedial plans. 相似文献
The experimental results also indicated that the ratio of the oil-layer thickness in the well to that in the porous medium is not a constant as is sometimes assumed in practice. Further, estimates of the oil thickness in the medium based on the oil thickness in wells and on capillary properties measured in the laboratory were sensitive to the values of the parameters used in these estimates. The measured thickness of the oil layer in a monitoring well alone may not yield reliable estimates of the amount of oil in the subsurface, and assuming that the oil-thickness ratio is a constant can lead to inadequate site assessments and inappropriate remedial plans. 相似文献
3.
4.
Evidence for Elevated Levels of Arsenic in Public Wells of Bangladesh Due To Improper Installation 
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下载免费PDF全文 I. Choudhury K. M. Ahmed M. Hasan M. R. H. Mozumder P. S. K. Knappett T. Ellis A. van Geen 《Ground water》2016,54(6):871-877
One of the mainstays of mitigation to reduce the exposure of the rural population of Bangladesh to arsenic (As) from private, mostly <90‐m deep wells over the past 15 years has been the installation of over 300,000 deeper community wells. A comprehensive testing campaign previously conducted across a 180 km2 of area of Bangladesh identified 9 out of total of 927 wells >90 m deep that contained >50 µg/L arsenic. We show here that for five of these nine wells, conductivity profiles obtained after spiking the well bore with salt indicate a shallow leak that could explain the high As in the well water. In two of the five leaky wells, the presence of additional screens at the depth of the leak was documented with a downhole camera. The downhole camera did not detect anomalies in the construction of the remaining three leaky wells or in the four wells that did not leak. The four wells that did not leak were all >150‐m deep and located in two villages separated by less than 500 m. Excluding these two villages and a handful of leaky wells, the results indicate an aquifer that is consistently low in As over a sizeable area at depths >90 m. Isolated cases of public wells that are elevated in As that have been reported elsewhere in Bangladesh may therefore reflect improper installation rather than actual contamination of the deep aquifer. 相似文献
5.
Probability of earthquake occurrence and magnitude estimation in the post shut-in phase of geothermal projects 总被引：1，自引：1，他引：0
Induced seismicity in geothermal projects is observed to continue after shut-in of the fluid injection. Recent experiments show that the largest events tend to occur after the termination of injection. We use a probabilistic approach based on Omori??s law and the Gutenberg?CRichter magnitude?Cfrequency distribution to demonstrate that the probability of exceeding a certain maximum magnitude still increases after shut-in. This increase is governed by the exponent of Omori??s law q and the Gutenberg?CRichter b value. For a reduced b value in the post-injection phase, the probability of occurrence directly after shut-in can be even higher than the corresponding probability for an ongoing injection. For the reference case of q?=?2 and a 10% probability at shut-in time t S to exceed a given maximum magnitude, we obtain an increase to 14.6% for t?=?2t S at a constant Gutenberg?CRichter b value after shut-in. A reduction of the b value by one quarter leads to a probability of 20.5%. If we consider a constant probability level of occurrence for an event larger than a given magnitude at shut-in time, this maximum magnitude increases by 0.12?units for t?=?2t S (0.26?units for a reduced b value). For the Soultz-sous-Forêts (France) injection experiment in 2000, recent studies reveal q?=?9.5 and a b value reduction by 14%. A magnitude 2.3 event 9?h after shut-in falls in the phase with a probability higher than for the continued injection. The probability of exceeding the magnitude of this post-injection event is determined to 97.1%. 相似文献
6.
The forward and inversion methods of resistivity tomography with a vertical line current source (RTVLCS) were introduced in this paper. The technique was applied to the evaluation of residual oil saturation of the reservoir studied in an old oil region. The observed water saturation during the course of the measurement of RTVLCS and subsequent drilling records proved the reliability of our result. However, our model has not included the influence of all factors such as electrical contact resistance between the metal casing and surrounding rocks and of the size of the metal cased well taken as a vertical line current source (VLCS). In addition, RTVLCS was carried out after the well had been in use for many years, while the initial resistivity values used in the inversion were obtained from the resistivity curve logged upon the completion of the well. Therefore, the residual oil saturation obtained by RTVLCS is relative and has not complete consistency with real situations, and can only be used as reference for adjusting a plan for oil production in the mid- or post-phase of an oilfield. 相似文献
7.
Sherl L. Chapman 《Ground water》1972,10(4):49-51
Abstract In 1962, a 2,980-foot deep well was drilled for D. I. Foreman in Middle Castle Creek Valley, Owyhee County, Idaho. This well, which flowed approximately 3,600 gpm, yielded water of 170°F from basalt and silicic volcanic formations; original shut-in pressure was 105 psi. However, leakage began to occur around the casing, and in 1967, a suit was filed on behalf of the Idaho Department of Water Administration to have the well repaired.
The Andrew Well Drilling Company, of Idaho Falls, was hired to repair the well, and was on the site in November 1968. Additional casing, packers, and pressure grouting sealed the well adequately. The effect of closure of the foreman well on ground water of the entire area was dramatic. As an example, within 8 hours of closure, water in an observation well 5.7 miles away, rose more than a tenth of a foot. Net increase in this observation well since closure has been 26 feet. 相似文献
The Andrew Well Drilling Company, of Idaho Falls, was hired to repair the well, and was on the site in November 1968. Additional casing, packers, and pressure grouting sealed the well adequately. The effect of closure of the foreman well on ground water of the entire area was dramatic. As an example, within 8 hours of closure, water in an observation well 5.7 miles away, rose more than a tenth of a foot. Net increase in this observation well since closure has been 26 feet. 相似文献
8.
本文利用室内电阻率测试的方法研究了研究了饱和土和不饱和土两类土中含油污水的侵入量对其导电性的影响.测试结果表明,对于不饱和土,含油污水的侵入会改变土的饱和度从而引起其电阻率的降低,侵入量越大其电阻率越低;而饱和土的电阻率随含油污水侵入量的增大而增大直到趋于稳定.基于此,通过室内模拟土层污染和野外实地观测污染土层的方式研究了含油污水污染不同饱和度土层的电剖面异常特征,在不饱和土层中污染区域表现为相对低阻异常区而在饱和土层中表现为相对高阻异常区.通过对比不同时期的监测结果显示异常区的范围随污染区的变化而变化,并可反映出污染区的实际分布.文章分析了利用电阻率法进行含油污水污染地下介质调查的几个模糊点,对提高探测效果具有指导意义. 相似文献
9.
A laboratory study was conducted to determine the efficiency of different aqueous concentrations of an alcohol ethoxylate surfactant in washing residual levels of an oil [automatic transmission fluid (ATF)] from sandy soil. Five glass columns packed with the soil were prepared in a manner that simulated conditions leading to residual saturation in an actual oil leak. Each of four columns was washed continuously with 28 pore volumes of solution by pumping either 0.0 percent (water), 0.5 percent, 1.0 percent, or 2.0 percent aqueous surfactant solutions through the columns. The fifth column was washed intermittently with 28 pore volumes of a 1.0 percent surfactant solution. Water washed only 25.5 percent of the ATF from the column soil, while the 0.5 percent, 1 percent, and 2 percent surfactant solutions washed 55 percent, 60 percent, and 72.8 percent of the ATF, respectively. The distribution of the ATF remaining in the column after washing showed that the ATF removed by water was mainly from the outlet side of the column, while the ATF removed by the 2.0 percent surfactant solution was mainly from the inlet side of the column. This observation indicated that different mechanisms were involved; namely, the displacement of oil through the soil-pore space, the dispersion of oil due to reduced surface tension, and the solubilization of oil by surfactant micelles. In the case of water, the displacement of oil was the main washing mechanism, while all three mechanisms were operative during surfactant washing. ATF dispersion and solubilization were improved at higher surfactant concentrations. The column that was washed intermittently to pulse ATF from dead end pores did not show a significant improvement over the column that was continuously washed with the same 1.0 percent surfactant solution. The results show promising potential for application in the field and will be further investigated in a two-dimensional model aquifer. 相似文献
10.
崖南区是琼东南盆地已证实的富生烃区,几口已钻井都已证实主要目的层段为高压地层,利用常规的压力预测方法预测新钻井的压力会出现较大的误差.若是从区域应力角度入手预测新钻井的压力误差会减小,其预测基础为岩性模型.对于已开发的油气田,利通常规的岩性建模方法可以建立较好的岩性模型;但是对于崖南区而言,由于地震资料品质不是很好,同时本区钻井较少,很难通过常规的建模方法建立岩性模型,所以本区研究重点是如何利用少井建立岩性模型.通过研究认为若完成崖南区的岩性建模必须改进建模流程,改进的岩性建模流程克服了常规岩性建模在崖南区存在的问题,主要有三方面的优点:1)不采用相模型约束岩性建模,解决了由于研究区相模型划相较粗很难约束岩性模型建立的问题;2)属性模型控制岩性模型的横向变化趋势,解决了几种常规属性与岩性间没有较好关系的问题;3)利用泥质含量结合岩性资料建立岩性体,得到的岩性模型比较接近实际情况.C井钻前完成岩性模型建立,利用C井井点位置提取岩性数据与本井钻后录井岩性数据对比,发现预测岩性与录井岩性的吻合程度很高,证明改进的岩性建模思路在崖南少井区可用. 相似文献
11.
We present a semi-analytical, combinatorial approach to compute three-phase capillary entry pressures for gas invasion into pore throats with constant cross-sections of arbitrary shapes that are occupied by oil and/or water. For a specific set of three-phase capillary pressures, geometrically allowed gas/oil, oil/water and gas/water arc menisci are determined by moving two circles in opposite directions along the pore/solid boundary for each fluid pair such that the contact angle is defined at the front circular arcs. Intersections of the two circles determine the geometrically allowed arc menisci for each fluid pair. The resulting interfaces are combined systematically to allow for all geometrically possible three-phase configuration changes. The three-phase extension of the Mayer and Stowe – Princen method is adopted to calculate capillary entry pressures for all determined configuration candidates, from which the most favorable gas invasion configuration is determined. The model is validated by comparing computed three-phase capillary entry pressures and corresponding fluid configurations with analytical solutions in idealized triangular star-shaped pores. It is demonstrated that the model accounts for all scenarios that have been analyzed previously in these shapes. Finally, three-phase capillary entry pressures and associated fluid configurations are computed in throat cross-sections extracted from segmented SEM images of Bentheim sandstone. The computed gas/oil capillary entry pressures account for the expected dependence of oil/water capillary pressure in spreading and non-spreading fluid systems at the considered wetting conditions. Because these geometries are irregular and include constrictions, we introduce three-phase displacements that have not been identified previously in pore-network models that are based on idealized pore shapes. However, in the limited number of pore geometries considered in this work, we find that the favorable displacements are not generically different from those already encountered in network models previously, except that the size and shape of oil layers that are surrounded by gas and water are described more realistically. The significance of the results for describing oil connectivity in porous media accurately can only be evaluated by including throats with more complex cross-sections in three-phase pore-network models. 相似文献
12.
山东胜利油田角07井注水地震序列的演化及其机制 总被引：3，自引：0，他引：3
1985年12月至1986年1月发生的山东省胜利油田角07井注水地震序列,经历了特有的演化过程,即全序列可分解为4个子序列,且子序列逐渐由震群型向主余型过渡.前期地震(最大地震之前)呈升级趋势,地震b值前期高于后期,地震时间结构的分数维D则前期低于后期,以及较大地震的lg△t-lgt前期较为紊乱,而后期线性相关等.计算表明,注水后岩石孔隙压力大于临界孔隙压力,从而诱发了地壳浅部岩石低初始应力的提前释放,而水的渗透作用则导致岩石孔隙压力随时间由高度非均匀分布向相对均匀分布转换.角07井地震序列的演化与这一物理过程有关. 相似文献
13.
A small but significant proportion of all existing monitoring wells may be affected by leakage through the casing, usually at joints. Casing leakage can render data obtained from a monitoring well unreliable. Anomalous water level, water quality, or isotope data from a particular well are an indication of possible leakage. The occurrence of a casing leak can be confirmed by means of a pressure test using water. The magnitude of the leakage flow can be estimated from the pressure test or from the observed head anomaly. Casing leaks can be largely prevented with adequate care during monitoring well installation, but the possibility that data may be affected by casing leaks should always be taken into account during hydrogeological investigations. 相似文献
14.
A. Saraswat G. R. Reddy C. Umashankar Y. M. Parulekar A. K. Ghosh 《Bulletin of Earthquake Engineering》2016,14(11):3259-3282
Nuclear fuel fabrication and reprocessing facilities have glove boxes that are extensively used as a primary containment for radiological material. These equipment are maintained under negative pressure using ventilation system and possess high degree of leak tightness. Sometimes, they are used as a standalone structure and many a times, interconnected to each other. Normally, they are not anchored to the floor, which raises serious concerns about their seismic performance. To check seismic stability of the glove boxes and evaluate safety margins in design, tri directional fullscale shake table experiments of two interconnected glove boxes had been carried out. Two configurations were compared; in first, both the boxes were connected through flexible linkage (material transfer tunnel) and in second both were rigidly connected via structural members. Objective of experiments was to observe effects of seismic excitation on leak tightness, structural integrity and overall stability of two interconnected glove boxes. Subsequently, nonlinear finite element analysis was carried out to establish and develop analysis methodology. Experimental results were utilized for model benchmarking. Furthermore, a numerical method was developed to determine safe upper bounds on sliding displacements. This paper highlighted critical findings emanated from experimental results and examined their effect on seismic stability. Enhanced seismic stability in case of rigidly connected boxes was observed. Rigid body motions (mainly sliding and low magnitude rocking) dominated the response with very limited effect of elastic motions. Methodology used for modelling and analyzing glove boxes under seismic loading using finite element methods was also presented. 相似文献
15.
by L.F. Konikow 《Ground water》2010,48(1):106-110
The yield (or discharge) of constant-speed pumps varies with the total dynamic head (or lift) against which the pump is discharging. The variation in yield over the operating range of the pump may be substantial. In groundwater simulations that are used for management evaluations or other purposes, where predictive accuracy depends on the reliability of future discharge estimates, model reliability may be enhanced by including the effects of head-capacity (or pump-capacity) relations on the discharge from the well. A relatively simple algorithm has been incorporated into the widely used MODFLOW groundwater flow model that allows a model user to specify head-capacity curves. The algorithm causes the model to automatically adjust the pumping rate each time step to account for the effect of drawdown in the cell and changing lift, and will shut the pump off if lift exceeds a critical value. The algorithm is available as part of a new multinode well package (MNW2) for MODFLOW. 相似文献
16.
Andrea D'Aniello Sigrún Tómasdóttir Bergur Sigfússon Massimiliano Fabbricino 《Ground water》2021,59(5):677-693
Particular attention is paid to the risk of carbon dioxide (CO2) leakage in geologic carbon sequestration (GCS) operations, as it might lead to the failure of sequestration efforts and to the contamination of underground sources of drinking water. As carbon dioxide would eventually reach shallower formations under its gaseous state, understanding its multiphase flow behavior is essential. To this aim, a hypothetical gaseous leak of carbon dioxide resulting from a well integrity failure of the GCS system in operation at Hellisheiði (CarbFix2) is here modeled. Simulations show that migration of gaseous carbon dioxide is largely affected by formation stratigraphy, intrinsic permeability, and retention properties, whereas the initial groundwater hydraulic gradient (0.0284) has practically no effect. In two different scenarios, about 18.3 and 30.6% of the CO2 that would have been injected by the GCS system for 3 days could be potentially released again into the atmosphere due to a sustained leakage of the same duration. As the gaseous leak occurs, the aquifer experiences high pressure buildups, and the presence of a less conductive layer further magnifies these. Strikingly, the dimensional analysis showed that buoyant and viscous forces can be comparable over time within the predicted gaseous plumes, even far from the leakage source. Local pressure gradients, buoyant, viscous, and capillary forces all play an important role during leakage. Therefore, neglecting one or more of these contributions might lead to a partial prediction of gaseous CO2 flow behavior in the subsurface, giving space to incorrect interpretations and wrong operational choices. 相似文献
17.
Wm. Mansfield Adams 《Pure and Applied Geophysics》1965,61(1):113-122
Summary Direct access to the crust and the upper portion of the mantle may be achieved by letting a high temperature (>1100°C) reactor core melt the rock in which it is placed and fall through the resulting magma. Data gathering and retrieval seem feasible. A schematic design of the proposed instrument is given.There are many problems concerning the composition and conditions of the interior of the earth which will not be solved upon completion of the projectedMohole Project. Comparison of the continental crust with the oceanic crust, relative distribution of radioactivity under continents and oceans, and the investigation of the mantle itself require access to greater depths than the present drilling techniques permit. To achieve these aims, it is recommended that a dense, heatgenerating object (such as a nuclear reactor core) be placed in the top of a salt dome. The hot object would melt the salt and fall downward through the moten salt. The sinking object would pass out of the source salt bed into rock at such a depth, say 35 000 feet, that if a few percent of H2O is present at that depth, then a granitic rock would melt at about 700°C. However, encounter with SiO2 containing no water would require a much higher temperature of about 1700°C. The type of rock that actually exists immediately below the source salt bed is unknown, but it is probably not a granitic rock.Thermal considerations indicate that the hole will freeze shut after downward passage of the tool, leaving the tool inside a liquid bubble. If the tool can generate heat long enough to melt its way up, as well as down, it may be possible to obtain magma samples. Instrumentation for control and telemetry purposes appears extremely difficult. Initial emphasis is placed on attaining the depth of interest. 相似文献
18.
本文研究了唐山、天津和沧州地区的油井压裂记录,发现已充砂裂缝比未充砂裂缝条件下测得的瞬时闭合压力明显增高,并指出这一差值乃是由裂缝内砂子的支撑作用引起的。因此,在采用油井压裂记录确定地应力时,应考虑裂缝中砂子支撑作用带来的影响。 本文还对该地区具有未充砂条件下的油井压裂记录进行了分析,讨论了油井水力压裂应力测量的力学机制和解释方法。 最后讨论了油井水力压裂应力测量结果,得出该地区0——4000米深度范围内主应力随深度的线性变化关系,表明分布在该地区的北北东向断裂的现今活动,是属于右旋走向滑动类型。 相似文献
19.
Gerard P. Canevari 《Marine pollution bulletin》1982,13(2):49-54
The formation of stable sea water-in-crude oil emulsions after an oil spill was first reported after the Torrey Canyon wreck in 1967. The problem of handling this stable water (65%)-in-oil (35%) emulsion rather than oil is evidenced in the additional expensive on-site storage requirement as well as the handling difficulty with the viscous semi-solid emulsion. This paper details the results of an R&D program that has established the mechanism for the formation of this emulsion. This insight enabled a specific effective chemical demulsifier to be formulated. A treatment technique was devised that entails injecting the demulsifier into the oil spill emulsion as it is skimmed from the water surface. The emulsion is then rapidly separated into water-free oil and a clean-water phase that can be decanted back into the sea. Full-scale tests were successfully conducted by JBF Scientific Corp. using two types of commercial JBF DIP skimmers in a small concrete lined pond. 相似文献
20.
Ferenc Székely 《Ground water》2017,55(6):879-884
Modeling of the head recovery (buildup) in and intermittent operation of flowing wells lacks rigorous analytical tools. Presently different methods are applied in discharging and recovery phases. The presented reliable approximate solution considers a continuous free flow process and time variant screen loss parameters. The latter are temporarily set to large value to prevent inflow into the well bore during the single recovery or in repeated shut down periods. This method is called as screen loss control or SLC technique and is verified by means of comparative analysis with the constant rate pumping‐recovery test simulated in leaky aquifer. The evaluation of the free flow and recovery test in the free flowing well 28 (Artesia Heights) concluded with calibrated parameters close to those obtained in the earlier analyses based on split well flow process. The simulation of intermittent flowing well operation also underwent successful validation resulting in reasonable values of the Qw and s response functions. 相似文献