昆明市地热田越流含水系统中地下热水的数值模拟

深层基岩地下（热）水水化学污染问题日趋严重,急需定量而仿真地模拟和预报天然状态和各种人为工程经济活动下地下（热）水流动及溶质（或污染物）的运移。在充分认识地质、水文地质条件的基础上,建立了考虑温压变化和越流条件的昆明市地热田深层基岩地下热水系统中水流和溶质运移的准三维非稳定流数学模型。模型用于开采条件下地热田地下热水水位及 F^－、Cl^－浓度的模拟,模拟结果具有较高的仿真性,拟合误差一般小于 2％～5％,表明模型合理、可靠。应用所建模型预测了开采条件下昆明市地热田II块段地下热水流场和溶质浓度动态的变化趋势,并提出了控制地下热水环境进一步恶化的措施。     

青海西宁城南新区杜家庄地热田地下水的地球化学特征

依据青海省西宁市城南新区杜家庄地热田DR2005地热井地下热水的水化学资料,采用兰格利厄—路德维金图解法、同位素水文学方法、地球化学温标法等,对杜家庄地热田地下热水的补给机制、地下热水年龄、地热资源潜力等关键问题进行分析。分析结果表明杜家庄地热田地下热水源于大气降水入渗补给,但仍有现代冷水补给,地热田下部还存在着远高于DR2005地热井开采段温度的热储。依据研究区地热地质条件具可比性的地热生产井水化学动态观测资料推断,随着DR2005地热井开采时间的延续,地下热水水质将向淡化的方向发展。研究结果为杜家庄地热田的开发利用提供水文地球化学依据。     

胶东典型花岗岩热储地下热水水化学特征及热储研究

招远地热田位于胶东隆起区,元古代蚀变花岗岩分布广泛,地下热水微量元素丰富。为查明地下热水微量组分的赋存条件、花岗岩热储环境与地热资源量,利用地下热水水化学分析、热储分析及有效能源换算法,建立Gibbs模型,进行PHREEQC模拟并开展热储估算。研究结果显示：（1）地下热水水化学类型为Cl—Na型,与海水水化学类型一致,...     

广东省电白县观珠镇根竹园地热田地热资源储量计算与评价

电白县观珠镇根竹园地热田地热流体主要赋存于花岗岩风化裂隙和构造裂隙中,热储呈带状,受断裂构造控制,地热流体温度60℃～78℃,地热田规模较小,地面有温、热泉出露。本文通过地热田的地质条件、地下热水的温度、水质及储量,对开采的技术条件及储量作出评价,为合理开发地热资源提供水文地质依据。     

关于吉林市圣德泉地热资源的勘查研究

本文介绍了吉林圣德泉地热田(区)热储特征及其埋藏条件和地温场特征。热储层具多层结构,单层厚度大,构成沉积盆地型地热田。区内地温场温度较为稳定,属低温热水资源。地热流体单井产量较大,为较适宜至适宜开采区,水质为重碳酸钠型较低矿化的优质水源。地热田水量中等,可采取不定期轮换开采方法,热水温度43~62℃,属于低温地下热水。     

四川康定地热田地下热水成因研究

康定地热田位于四川盆地西缘山地和青藏高原的过渡地带,属于高热流背景上的深循环高温地热系统。本文以康定地热田地下热水为研究对象,通过采集地热田内的主要两个热显示区(榆林河和雅拉河地区)的温泉和地热井的地下热水样,进行水化学和稳定同位素测试分析,研究其地下热水的补给来源和热储温度。雅拉河地下热水的水化学类型主要为HCO_3-Na型水,榆林河地下热水的水化学类型主要为HCO_3·Cl-Na型水,均显示了深部地下热水沿断裂上涌与浅部冷水混合的特点。根据地下热水同位素的结果分析计算,康定地热田地下热水的起源均来自大气降水,雅拉河地下热水的补给高程为5 600~5 900 m,榆林河地下热水的补给高程为5 300~6 300 m,来源于南部的贡嘎山的可能性较大。榆林河地下热水具有明显的氧-18漂移现象,其原因为较高的热储温度,二氧化硅温标和阳离子温标的结果证明了这个判断,雅拉河地下热水的热储温度为172~188℃,榆林河地下热水的热储温度为192~288℃。     

西藏日喀则市查孜地热田水化学及同位素特征研究

查孜地热田位于青藏高原西南部。通过野外地质调查及地热钻孔揭露,发现该地热田具有较好的地热资源开发潜力。对该地热田地下热水的水文地球化学及同位素特征开展研究,发现地下热水为HCO₃-Na型; 热水与冷水的离子浓度存在差异,显示二者具有不同的物质来源,但又具有一定的水力联系。热水中的δD和δ¹⁸O同位素特征表明: 该地热田地下热水的主要补给来源为大气降水和冰雪融水,补给海拔为5 652 m以上; 大气降水和冰雪融水下渗并与沿断裂破碎带向上运移的地热流体混合后形成地下热水。断裂破碎带不仅是温泉的主要通道,也是地热流体的储集场所,地热田热水在地下运移滞留至少41 a。据SiO₂地热温标估算得出,该区地下热储温度为148.18 ~153.49 ℃,天然放热量为2 264.33×10¹² J/a。     

云南石林盆地地热地质特征及成因分析

结合石林盆地地热异常及地热钻孔资料,对石林盆地地热田的热储构造条件、地热地质特征及地下水化学特征进行研究,该地热田热储层为元古界震旦系白云岩、白云质灰岩,热水径流特征和地温场特征受九乡石垭口断裂、牛头山古陆控制。钻孔资料显示,地温梯度为(1.5~4.8)℃/100 m,地热类型为深循环层状地热田,地下热水水化学类型为HCO3-Ca。从水文地质条件看,地下热水补给有限,应控制地热水的开发利用。     

鲁北平原地温分布的特点及地热资源开发利用的前景

本文依据26口钻井的系统测温数据、1690个油层温度和21口自流热水井的资料,分析鲁两北平原地温场的特点和地下热水的赋存条件,提出地热田的基本模式,评述地区地下热水资源开发利用的前景。     

云南省宜良地热田基本特征研究及成因分析

对云南宜良盆地地热资源水文地质条件、热储层结构及地热田特征等分析研究,可将宜良地热田划分为3个相对独立的地热区,并对宜良地热田基本特征、形成机制、储集形式等规律进行探究,建立了宜良地热田热储概念模型,其成因模式为大气降水补给的断裂控热深循环型地热系统。研究区热储岩性主要为震旦系灯影组白云岩,为岩溶型层状热储,热储温度一般在43℃~55℃之间,埋藏深度一般在800~1200m。宜良断裂带为水热对流循环提供了良好的通道和储集空间,地下热水在震旦系灯影组岩溶含水层中富集,最终形成宜良地热田。     

Application of multiple-point geostatistics on modelling groundwater flow and transport in a cross-bedded aquifer (Belgium)

Sedimentological processes often result in complex three-dimensional subsurface heterogeneity of hydrogeological parameter values. Variogram-based stochastic approaches are often not able to describe heterogeneity in such complex geological environments. This work shows how multiple-point geostatistics can be applied in a realistic hydrogeological application to determine the impact of complex geological heterogeneity on groundwater flow and transport. The approach is applied to a real aquifer in Belgium that exhibits a complex sedimentary heterogeneity and anisotropy. A training image is constructed based on geological and hydrogeological field data. Multiple-point statistics are borrowed from this training image to simulate hydrofacies occurrence, while intrafacies permeability variability is simulated using conventional variogram-based geostatistical methods. The simulated hydraulic conductivity realizations are used as input to a groundwater flow and transport model to investigate the effect of small-scale sedimentary heterogeneity on contaminant plume migration. Results show that small-scale sedimentary heterogeneity has a significant effect on contaminant transport in the studied aquifer. The uncertainty on the spatial facies distribution and intrafacies hydraulic conductivity distribution results in a significant uncertainty on the calculated concentration distribution. Comparison with standard variogram-based techniques shows that multiple-point geostatistics allow better reproduction of irregularly shaped low-permeability clay drapes that influence solute transport.     

Modeling of transient groundwater flow,pollutant transport,and biodegradation in an aquifer with large hydraulic head variations

Industrially sourced dense non-aqueous phase liquids (DNAPLs) contaminated an alluvial aquifer in France decades ago. The location(s) and nature of the pollution source zone(s) were unknown, and the dissolved concentrations of volatile organic compounds in the monitoring wells varied greatly with time. The aquifer was in hydraulic equilibrium with an artificial canal whose water level was highly variable (up to 5 m). These variations propagated into the aquifer, causing changes in the groundwater flow direction; a transient numerical model of flow and solute transport showed that they correlate with the concentration variations because the changes in the flow direction resulted in the contaminant plume shifting. The transient hydrogeological numerical model was built, taking into account solvent biodegradation with first-order chain, since biodegradation has a significant influence on the pollutant concentration evolution. The model parameterization confirms the position of the source zones among the potential troughs in the bedrock where DNAPLs could have accumulated. The groundwater model was successfully calibrated to reproduce the observed concentration variations over several years and allowed a rapid validation of the hypotheses on the functioning of the polluted system.     

Sensitivity Analysis of a Combined Groundwater Flow and Solute Transport Model Using Local-Grid Refinement: A Case Study

Combining groundwater flow models with solute transport models represents a common challenge in groundwater resources assessments and contaminant transport modeling. Groundwater flow models are usually constructed at somewhat larger scales (involving a coarser discretization) to include natural boundary conditions. They are commonly calibrated using observed groundwater levels and flows (if available). The groundwater solute transport models may be constructed at a smaller scale with finer discretization than the flow models in order to accurately delineate the solute source and the modeled target, to capture any heterogeneity that may affect contaminant migration, and to minimize numerical dispersion while still maintaining a reasonable computing time. The solution that is explored here is based on defining a finer grid subdomain within a larger coarser domain. The local-grid refinement (LGR) implemented in the Modular 3D finite-difference ground-water flow model (MODFLOW) code has such a provision to simulate groundwater flow in two nested grids: a higher-resolution sub-grid within a coarse grid. Under the premise that the interface between both models was well defined, a comprehensive sensitivity and uncertainty analysis was performed whereby the effect of a parameter perturbation in a coarser-grid model on transport predictions using a higher-resolution grid was quantified. This approach was tested for a groundwater flow and solute transport analysis in support of a safety evaluation of the future Belgian near-surface radioactive waste disposal facility. Our reference coarse-grid groundwater flow model was coupled with a smaller fine sub-grid model in two different ways. While the reference flow model was calibrated using observed groundwater levels at a scale commensurate with that of the coarse-grid model, the fine sub-grid model was used to run a solute transport simulation quantifying concentrations in a hypothetical well nearby the disposal facility. When LGR coupling was compared to a one-way coupling, LGR was found to provide a smoother flow solution resulting in a more CPU-efficient transport solution. Parameter sensitivities performed with the groundwater flow model resulted in sensitivities at the head observation locations. These sensitivities identified the recharge as the most sensitive parameter, with the hydraulic conductivity of the upper aquifer as the second most sensitive parameter in regard to calculated groundwater heads. Based on one-percent sensitivity maps, the spatial distribution of the observations with the highest sensitivities is slightly different for the upper aquifer hydraulic conductivity than for recharge. Sensitivity analyses were further performed to assess the prediction scaled sensitivities for hypothetical contaminant concentrations using the combined groundwater flow and solute transport models. Including all pertinent parameters into the sensitivity analysis identified the hydraulic conductivity of the upper aquifer as the most sensitive parameter with regard to the prediction of contaminant concentrations.     

基于多源数据的弱透水层水文地质参数反演研究

弱透水层是含水层系统的重要组成部分,其水文地质参数的准确获取一直以来都是研究难点,传统室内试验难以克服应力状态及环境变化对土层参数的影响,因此如何在原位状态下评价其水文地质参数有着重要意义。选取呼和浩特盆地某淤泥层为研究对象,基于抽水试验和溶质运移试验获得的多源数据,采用基于控制体积有限差分法的非结构化网格（Unstructured Grid）方法,建立三维地下水流-溶质运移耦合模型,对弱透水层水文地质参数进行反演。结果显示:模型计算的抽水井中水位和溶质浓度变化规律与实际观测数据能够较好拟合,模型识别出的抽水含水层渗透参数（4.8 m/d）与通过解析法计算得出的结果（4.17 m/d）相近,建立的数值模型符合实际水文地质条件;反演得到淤泥质弱透水层垂向渗透系数为1.2×10?4 m/d、储水率为1.0×10?5 m?1。基于多源数据的参数反演方法可为弱透水层参数研究提供借鉴。     

Assessing Groundwater Resource Vulnerability by Coupling GIS-Based DRASTIC and Solute Transport Model in Ajmer District,Rajasthan

Groundwater aquifer vulnerability has been assessed by incorporating the major geological and hydrogeological factors that affect and control the groundwater contamination using GIS-based DRASTIC model along with solute transport modeling. This work demonstrates the potential of GIS to derive a vulnerability map by overlying various spatially referenced digital data layers (i.e., depth to water, net recharge, aquifer media, soil media, topography, the impact of vadose zone and hydraulic conductivity) that portrays cumulative aquifer sensitivity ratings in Kishangarh, Rajasthan. It provides a relative indication of groundwater aquifer vulnerability to contamination. The soil moisture flow and solute transport regimes of the vadose zone associated with specific hydrogeological conditions play a crucial role in pollution risk assessment of the underlying groundwater resources. An effort has been made to map the vulnerability of shallow groundwater to surface pollutants of thestudy area, using soil moisture flow and contaminant transport modeling. The classical advection-dispersion equation coupled with Richard’s equation is numerically simulated at different point locations for assessing the intrinsic vulnerability of the valley. The role of soil type, slope, and the land-use cover is considered for estimating the transient flux at the top boundary from daily precipitation and evapotranspiration data of the study area. The time required by the solute peak to travel from the surface to the groundwater table at the bottom of the soil profile is considered as an indicator of avulnerability index. Results show a high vulnerability in the southern region, whereas low vulnerability is observed in the northeast and northern parts. The results have recognized four aquifer vulnerability zones based on DRASTIC vulnerability index (DVI), which ranged from 45 to 178. It has been deduced that approximately 18, 25, 34, and 23% of the area lies in negligible, low, medium and high vulnerability zones, respectively. The study may assist in decision making related to theplanning of industrial locations and the sustainable water resources development of the selected semi-arid area.     

Study of geothermal water intrusion due to groundwater exploitation in the Puebla Valley aquifer system, Mexico

Significant intrusion of geothermal water into fresh groundwater takes place in the Puebla Valley aquifer system, Mexico. The decline in the potentiometric surface due to the overexploitation of the groundwater induces this intrusion. This hydrological system comprises three aquifers located in Plio-Quaternary volcanic sediments and Mesozoic calcareous rocks. The hydraulic balance of the aquifer shows that the annual output exceeds the natural inputs by 12 million m³. Between 1973 and 2002, a drop in the potentiometric surface, with an 80 m cone of depression, was identified in a 5-km-wide area located southwest of the city of Puebla. Chemical analyses performed on water samples since 1990 have shown an increase in total dissolved solids (TDS) of more than 500 mg/L, coinciding with the region showing a cone of depression in the potentiometric surface. A three-dimensional flow and transport model, based on the hydrogeological and geophysical studies, was computed by using the MODFLOW and MT3D software. This model reproduces the evolution of the aquifer system during the last 30 years and predicts for 2010 an additional drawdown in the potentiometric surface of 15 m, and an increase in the geothermal water intrusion.     

基于GMS软件对某矿区松散层孔隙水污染的数值模拟研究

以云南某矿区为研究对象,在详细调查区域水文地质条件和已有资料的基础上,结合调查区监测井,利用GMS软件建立研究区域地下水水流场模型和溶质运移模型。模型计算了在合理误差范围内的水流场模型并预测了硫酸盐在持续泄漏730d、180d后切断泄漏源,硫酸盐的迁移过程。研究结果表明:随着持续泄漏时间的增加,调查区域北部边界附近受到污染的浓度越高、污染范围越广,超标的污染物在北部边界区域进入岩溶含水层,遇到岩溶带会加速污染物向下游运移,破坏下游水质、危及下游村庄饮用水安全。     

用地下水潮汐效应确定潜水含水层水文地质参数

目前对潜水含水层地下水潮汐效应和水文地质参数求解方法的研究相对较少.通过对福建古雷半岛滨海潜水含水层地下水潮汐效应和海水潮汐动态的观测, 运用Fourier频谱分析方法确定了研究区海水潮汐波动方程(波动特征参数), 并以此作为地下水的边界条件, 推导了潜水含水层地下水潮汐效应的波动方程, 利用最小二乘法以地下水水位波动观测值为目标函数对潜水含水层的渗透系数与重力给水度的比值进行了反演识别, 为类似地区水文地质参数的确定提供了借鉴, 也为该区后续地下水中溶质迁移规律的研究奠定了基础.      

北京市朝阳区沙子营垃圾污染物在潜水含水层中迁移规律的现场模拟实验

选择北京平原区水文地质、环境地质等方面都比较典型的沙子营垃圾堆放场,建立了其水文地质模型。在充分收集资料、分析得出部分计算所需参数后,采用现场弥散实验、勘查取样测试等方法,求得了该含水层的弥散系数等参数;用二维非稳定流溶质运移方程对污染物在此含水层中的迁移扩散规律、速度和污染范围等进行了模拟计算;采用现场钻探、取样测试分析等方法,评价了该含水层的实际污染状况。实验模拟计算和现场调查结果表明:污染物在潜水含水层中的运移规律遵循二维非稳定流场中的溶质运移方程,污染物在潜水含水层中的运移速度约为86.25m/a,迁移扩散主要发生在地下水流向上,侧向扩散宽度极小,是地下水流向上的1/17。