共查询到20条相似文献，搜索用时 104 毫秒
1.
This paper points out two numerical problems linked to the resolution of compositional multiphase flow models for porous media
with the finite‐volume technique. In particular, we consider fluid mixtures featuring fast mass transfers between the phases,
hence stiff. In this context, we show how the computation of mass exchange kinetics can be expensive and that erroneous saturation
front locations arise. A numerical splitting method is developed which is proven to be stable with advection‐type time steps,
whatever the stiffness of the mass transfer. The erroneous front location problem is illustrated and shown to be intrinsically
linked to the numerical diffusion. If we assume that the fluids are in thermodynamical equilibrium, we find that spurious
solutions can be avoided by deriving and solving a new uncoupled hyperbolic equation for the saturation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
3.
A new model for unsaturated flow in porous media, including capillary hysteresis and dynamic capillary effects, is analyzed. Existence and uniqueness of solutions are established and qualitative and quantitative properties of (particular) solutions are analyzed. Some results of numerical computations are given. The model under consideration incorporates simple ‘play’-type hysteresis and a dynamic term (time-derivative with respect to water content) in the capillary relation. Given an initial water content distribution, the model determines which parts of the flow domain are in drainage and which parts are in imbibition. The governing equations can be recast into an elliptic problem for fluid pressure and an evolution equation for water content. Standard methods are used to obtain numerical results. A comparison is given between J.R. Philip's semi-explicit similarity solution for horizontal redistribution in an infinite one-dimensional domain and solutions of the new model. 相似文献
4.
LI Wenpeng 《《地质学报》英文版》2008,(5)
Firstly,the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory.The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented,which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake.And secondly,with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference,a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory. Meanwhile,the model was applied to model potassium/magnesium transport in Qarban Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarban Salt Lake. 相似文献
5.
Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer (salt deposit) in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea oftransport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system (salt deposits) was developed by using the Pitzer theory.Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/Magnesium in the mining of salt deposits in Qarhan Salt Lake. 相似文献
6.
T. Kuppusamy 《国际地质力学数值与分析法杂志》1993,17(7):457-469
Aquifer contamination by organic chemicals in subsurface flow through soils due to leaking underground storage tanks filled with organic fluids is an important groundwater pollution problem. The problem involves transport of a chemical pollutant through soils via flow of three immiscible fluid phases: namely air, water and an organic fluid. In this paper, assuming the air phase is under constant atmospheric pressure, the flow field is described by two coupled equations for the water and the organic fluid flow taking interphase mass transfer into account. The transport equations for the contaminant in all the three phases are derived and assuming partition equilibrium coefficients, a single convective – dispersive mass transport equation is obtained. A finite element formulation corresponding to the coupled differential equations governing flow and mass transport in the three fluid phase porous medium system with constant air phase pressure is presented. Relevant constitutive relationships for fluid conductivities and saturations as function of fluid pressures lead to non-linear material coefficients in the formulation. A general time-integration scheme and iteration by a modified Picard method to handle the non-linear properties are used to solve the resulting finite element equations. Laboratory tests were conducted on a soil column initially saturated with water and displaced by p-cymene (a benzene-derivative hydrocarbon) under constant pressure. The same experimental procedure is simulated by the finite element programme to observe the numerical model behaviour and compare the results with those obtained in the tests. The numerical data agreed well with the observed outflow data, and thus validating the formulation. A hypothetical field case involving leakage of organic fluid in a buried underground storage tank and the subsequent transport of an organic compound (benzene) is analysed and the nature of the plume spread is discussed. 相似文献
7.
A supersaline, metal-rich brine (ca. 40 weight% total chloride salt) was extracted from 3708 m depth of well WD-1a in the
Kakkonda Granite by reverse circulation after a standing time about 196 hours. The estimated borehole temperature exceeds
500 °C near the bottom. Tritium content and the relationship between δD and δ18O show that the injected borehole fluid (river water) evidently mixed with an isotopically heavy and ancient fluid. The phase
analysis showed that a gas phase separated from a brine and that a brine concentrated in the borehole as the borehole temperature
recovered after cooling by drilling fluids. We think the original fluid was trapped in the Kakkonda Granite and mixed with
the borehole fluid through fine fractures induced by thermal stress.
Received: 15 May 1997 / Accepted: 24 September 1997 相似文献
8.
Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer （salt deposit） in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system （salt deposits） was developed by using the Pitzer theory. Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarhan Salt Lake. 相似文献
9.
E.F. Kaasschieter 《Computational Geosciences》1999,3(1):23-48
Immiscible two‐phase flow in porous media can be described by the fractional flow model. If capillary forces are neglected,
then the saturation equation is a non‐linear hyperbolic conservation law, known as the Buckley–Leverett equation. This equation
can be numerically solved by the method of Godunov, in which the saturation is computed from the solution of Riemann problems
at cell interfaces. At a discontinuity of permeability this solution has to be constructed from two flux functions. In order
to determine a unique solution an entropy inequality is needed. In this article an entropy inequality is derived from a regularisation
procedure, where the physical capillary pressure term is added to the Buckley‐Leverett equation. This entropy inequality determines
unique solutions of Riemann problems for all initial conditions. It leads to a simple recipe for the computation of interface
fluxes for the method of Godunov.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
A new model for unsaturated flow in porous media, including capillary hysteresis and dynamic capillary effects, is analyzed. Existence and uniqueness of solutions are established and qualitative and quantitative properties of (particular) solutions are analyzed. Some results of numerical computations are given. The model under consideration incorporates simple play-type hysteresis and a dynamic term (time-derivative with respect to water content) in the capillary relation. Given an initial water content distribution, the model determines which parts of the flow domain are in drainage and which parts are in imbibition. The governing equations can be recast into an elliptic problem for fluid pressure and an evolution equation for water content. Standard methods are used to obtain numerical results. A comparison is given between J.R. Philip's semi-explicit similarity solution for horizontal redistribution in an infinite one-dimensional domain and solutions of the new model. 相似文献
11.
Yu Liu 《地下水科学与工程》2013,1(1):70-73
Three brine migration models in underground waters were compared to solve the problem of high-density brine migration in underground fresh waters. As shown by the example of brine occurrence in salt dumps, it is preferable to use the model of variable-density solution migration for real layered hydrogeological systems. 相似文献
12.
Liu Yu 《Moscow University Geology Bulletin》2011,66(4):290-292
A model of the intrusion of high-density immiscible liquids into underground waters was compared to a model of variable-density
solution migration to solve the problem of high-density brine migration in underground fresh waters. As shown by the example
of brine occurrence in salt dumps, it is preferable to use the second model for real layered hydrogeological systems. 相似文献
13.
Identifying sources of salinization using hydrochemical and isotopic techniques, Konarsiah, Iran 总被引：2，自引：2，他引：0
Mehdi Zarei Ezzat Raeisi Broder J. Merkel Nicolai-Alexeji Kummer 《Environmental Earth Sciences》2013,70(2):587-604
Konarsiah salt diapir is situated in the Simply Folded Zone of the Zagros Mountain, south Iran. Eight small permanent brine springs emerge from the Konarsiah salt body, with average total dissolved solids of 326.7 g/L. There are numerous brackish to saline springs emerging from the alluvial and karst aquifers adjacent to the diapir. Concerning emergence of Konarsiah diapir in the study area, halite dissolution is the most probable source of salinity in the adjacent aquifers. However, other sources including evaporation and deep brines through deep Mangerak Fault are possible. The water samples of the study area were classified based on their water-type, salinity, and the trend of the ions concentration curves. The result of this classification is in agreement with the hydrogeological setting of the study area. The hydrochemical and isotopic evaluations show that the groundwater samples are the result of mixing of four end members; Gachsaran sulfate water, Sarvak and Asmari carbonate fresh waters, and diapir brine. The molar ratios of Na/Cl, Li/Cl, Br/Cl, and SO4/Cl; and isotopic signature of the mixed samples justify a groundwater mixing model for the aquifers adjacent to the salt diapir. The share of brine in each adjacent aquifer was calculated using Cl mass balance. In addition, concentrations of 34 trace elements were determined to characterize the diapir brine and to identify the possible tracers of salinity sources in the mixed water samples. B, Mn, Rb, Sr, Cs, Tl, and Te were identified as trace elements evidencing contact of groundwater with the salt diapir. 相似文献
14.
The Gavbast karstic aquifer located in southern Iran is in direct contact with an exposed salt diapir. To assess the influence of the diapir on the quality of groundwater in the karstic aquifer, electrical conductivity, total dissolved solids, flow rate, temperature and major ion concentrations were measured at 57 sampling sites, including springs, surface waters and wells. A conceptual model of groundwater flow is proposed for the Gavbast karstic aquifer based on the geological setting, water budget, local base of erosion, and hydrochemistry of the sampling sites. The model suggests two subbasins in the Gavbast Anticline draining into two distinct discharging alluvial sections. Unexpectedly, groundwater discharging from the carbonate Gavbast aquifer is saline or brackish and water is of chloride type. The study indicates that the source of salinity of the Gavbast aquifers is infiltration of surface diapir-derived brine into the aquifer. The contribution of the diapir brine in the Gavbast karst aquifer is calculated about 4 L/s, using chloride mass balance. Construction of salt basins to evaporate brine discharging from the diapir springs is proposed to reduce the salinity of karst water. A row of strategically placed wells in the Gavbast karst aquifer would potentially exploit large volumes of fresh groundwater before it is contaminated by the salt. Such low-cost remediation should allow the agricultural exploitation of 40 km2 of currently barren land. 相似文献
15.
滨海地区改良软土会受到海水的长期浸泡作用,为获得其力学性能随时间的演化规律,依据海水的主要物质成分和含量制备了盐水溶液。选取天津滨海新区的软土,掺入15%的水泥进行养护,为便于对比分析,选用有机质含量低的粉土作比较。为了说明盐溶液浸泡的作用,进行了盐水和淡水两种浸泡方式的对比试验。无侧限抗压强度试验结果表明,改良软土历经淡水溶液和盐溶液浸泡3 d后其强度差值达到最大,7 d和28 d养护龄期试样分别相差0.40、1.28 MPa,建议利用28 d的标准养护龄期强度作为设计参考值。利用Geo-Studio中的Seep/W和CTRAN模块模拟了盐溶液离子浸入试样的过程,发现离子在试样内部迁移2～3 d趋于平稳,主要迁移至离试样表层5 mm的区域范围内,数值计算结果与宏观力学试验结果相一致。 相似文献
16.
In this paper, we present a numerical model for simulating two-phase (oil–water and air–water) incompressible and immiscible flow in porous media. The mathematical model which is based on a fractional flow formulation is formed of two nonlinear partial differential equations: a mean pressure equation and a water saturation equation. These two equations can be solved in a sequential manner. Two numerical methods are used to discretize the equations of the two-phase flow model: mixed hybrid finite elements are used to treat the pressure equation, h-based Richards' equation and the diffusion term in the saturation equation, the advection term in the saturation equation is treated with the discontinuous finite elements. We propose a better way to calculate the nonlinear coefficients contained in our equations on each element of the discretized domain. In heterogeneous porous media, the saturation becomes discontinuous at the interface between two porous media. We show in this paper how to use the capillary pressure–saturation relationship in order to handle the saturation jump in the mixed hybrid finite element method. The two-phase flow simulator is verified against analytical solutions for some flow problems treated by other authors. 相似文献
17.
江陵凹陷成岩作用明显受沉积水介质性质的控制,成岩特征呈现出淡水-半咸水介质富碳酸盐胶结与盐湖富硬石膏胶结特征,两种胶结物含量存在互为消长的关系.从分析盐湖成因角度合理解释了成岩规律,认为盐湖环境成因受控于深层卤水和古气候.淡水一半咸水环境和盐湖环境成岩作用模式的差异导致两种环境抗压实的机理存在着差异,相应的高孔隙带分布规律不同,淡水一半咸水环境的早期碳酸盐胶结物被溶蚀形成高孔隙发育带;盐湖环境的膏岩层发育区有利于形成深部异常高压的"封存箱",保存原生孔隙,从而发育高孔隙带. 相似文献
18.
19.
Three-phase numerical model of water migration in partially frozen geological media: model formulation,validation, and applications 总被引：3，自引：0，他引：3
Scott L. Painter 《Computational Geosciences》2011,15(1):69-85
Water in the subsurface of the Earth’s cold regions—and possibly the subsurface of Mars—resides in the liquid, vapor, and
ice phases. However, relatively few simulations addressing full three-phase, nonisothermal water dynamics in below-freezing
porous media have been undertaken. This paper presents a nonisothermal, three-phase approach to modeling water migration in
partially frozen porous media. Conservation equations for water (as ice, liquid, and vapor) and a single gas species (in the
gas phase and dissolved in water) are coupled to a heat transport equation and solved by a finite-volume method with fully
implicit time stepping. Particular attention is given to the method of spatial differencing when the pore space is partially
filled with ice. The numerical model is able to reproduce freezing-induced water redistribution observed in laboratory experiments.
Simulations of Earth permafrost dynamics and of the formation and evolution of a planetary-scale cryosphere on Mars demonstrate
the new capabilities. 相似文献
20.
T. Mtombeni J. P. Maree C. M. Zvinowanda J. K. O. Asante F. S. Oosthuizen W. J. Louw 《International Journal of Environmental Science and Technology》2013,10(3):545-550
The use of desalination technologies which produce concentrated brines is acutely limited by inadequate waste brine disposal mechanisms such that the brine does not contaminate fresh water resources. The treatment of highly saline brine using freeze desalination technique trade marked as HybridICE? technology was investigated at pilot scale. The capacity of the HybridICE? process to generate fresh water by freeze desalination of brine was investigated in this study. Brine samples to feed into the HybridICE process unit were prepared in tanks with volume capacities between 1.0 and 10.0 m3 by dissolving common salt into tape water. The effects of refrigerant temperature, initial brine concentration, energy consumption were evaluated in relation to product ice quality. Feed brine samples were processed in batches in a closed system where it was continuously re-circulated to generate product ice and more concentrated residual small volume of brine stream. The quality of ice produced could be turned into potable water it terms of its low total dissolved salts and conductivity. The salt removal, based on the average chloride concentration in the ice samples, was 96 %. The energy utilization efficiency amounted to an average of ZAR 10.0/m3 water assuming energy cost of ZAR 0.39/kWh. The HybridICE? technology was shown to be a better option than other desalination technologies currently in use, in terms of energy utilization and cleaner by-products. 相似文献