How can remote sensing contribute in groundwater modeling?

Groundwater resources assessment, modeling and management are hampered considerably by a lack of data, especially in semi-arid and arid environments with a weak observation infrastructure. Usually, only a limited number of point measurements are available, while groundwater models need spatial and temporal distributions of input and calibration data. If such data are not available, models cannot play their proper role in decision support as they are notoriously underdetermined and uncertain. Recent developments in remote sensing have opened new sources for distributed spatial data. As the relevant entities such as water fluxes, heads or transmissivities cannot be observed directly by remote sensing, ways have to be found to link the observable quantities to input data required by the model. An overview of the possibilities for employing remote-sensing observations in groundwater modeling is given, supported by examples in Botswana and China. The main possibilities are: (1) use of remote-sensing data to create some of the spatially distributed input parameter sets for a model, and (2) constraining of models during calibration by spatially distributed data derived from remote sensing. In both, models can be improved conceptually and quantitatively.     

基于精细岩相约束的致密低渗储层参数建模研究——以红河油田92井区长812致密砂岩储层为例

鄂尔多斯盆地红河油田属于低孔、超低渗岩性油气藏.红河油田长8储层主要发育辫状河三角洲前缘水下分流河道和分流间湾两种沉积微相，并且在水下分流河道沉积微相中储层参数变化范围大，非均质性强，用常规的单一沉积相控建模方法无法对储层参数空间分布的非均质性进行充分表征.为了精确描述其储层参数及展布特征，以红河油田92井区长8₁²致密砂岩储层为例，在地质、岩心、测井等资料的基础上，应用基于精细岩相约束的储层参数建模方法建立了研究区三维地质模型，即先用沉积相发育模式约束建立沉积微相模型，再对水下分流河道沉积微相进行岩相细分，在沉积微相模型和不同岩相概率体的双重控制下建立岩相模型，然后以岩相模型为约束建立储层参数模型.结果表明，该方法建立的储层参数模型具有较高的可靠性，与地质认识符合较好，为该区油藏数值模拟提供了精确的地质模型，并为研究区下一步开发方案调整提供了地质依据.     

基于施工监测和三维模拟的临危边坡锚固方案研究

依据实际工程边坡案例,研究利用施工监测资料联合边坡稳定分析三维数值模拟确定临危边坡锚固方案的方法。研究表明,根据连续的监测资料可确定边坡内部剪切位移带的位置、发生区间和开始时间,据此可推测边坡潜在滑移面的位置和形状;边坡稳定分析有限元法三维模拟可以考虑坡体断面形态变化对坡体稳定和变形的影响,计算结果更具有合理性;以三维数值计算得到的坡体外部变形拟合实测变形和滑动面,依据临危边坡所处的极限平衡条件,可以确定坡体当前状态的等效力学参数;根据等效力学参数,通过三维模拟可以确定坡体最终形态下的潜在滑动面形状和位置,从而合理地确定加固锚索的长度和密度;工程运行情况表明,由此确定的加固方案是可靠的。     

基于Monte Carlo模拟的三维剖面地质界线不确定性分析

三维剖面地质界线是构建三维地质结构模型的重要基础数据,其不确定性会影响三维模型的几何形态和属性分布。以单一分布为假设前提的统计学不确定性分析方法掩盖了其他概率分布特征对模型的影响。突破单一误差分布条件的假设前提,本文使用Monte Carlo方法模拟了不同概率分布情况下地质剖面数据中地质界线的抽样采集,以及地质界线空间分布的不确定性;依托地质界线空间位置与地质属性的耦合关系,提出了用地质属性概率分布实现地质界线空间不确定性的定量可视化,并结合实际地质剖面探讨了多种概率分布条件下地质界线的空间不确定性。实例研究表明,基于Monte Carlo模拟的不确定性分析方法可以突破单一误差分布假设条件,结合地质属性概率可充分揭示出建模数据的内在不确定性与模型外在要素形态之间的耦合关系。     

A 3D-density simulation of the structure of the tectonosphere in the SW Indian Ocean

The method and results of 3D simulation of the structure of the tectonosphere in the SW Indian Ocean based on gravity field data are presented. The study included the formation of 3D-density models for several areas covering large tectonic structures in the SW Indian Ocean. The formation of 3D-density models of the structure of the tectonosphere was based on the results of structural analysis, which had been performed earlier for the gravity and anomalous magnetic fields, and 2D-density simulation along profiles crossing large structures in the study region. As a result of the 3D simulation, maps of the Moho discontinuity and maps of the density distribution in the oceanic crust were built for the largest structures of the region.     

大地电磁三维正、反演多核并行计算的设计与实现

首先以频点为并行粒度,完成了MT三维正演并行计算,然后将该算法引入共轭梯度法MT三维反演过程中的正演求数据的残差、反演方程右端项的求取、共轭梯度求解模型增量这三个计算环节中,使得MT三维反演中的主要计算量实现并行化。对编制的MT三维正、反演并行计算程序,在多核工作站上通过理论地电模型进行了正演试算和反演验证,并在串行和并行两种计算方式下进行了计算效率对比。     

基于真三维GIS的地质构造模型与空间分析

带有断层的地质体建模难于层状地层,是当前研究的难点,模型完成后的三维空间分析功能目前也处于研究阶段,是当前研究的热点.以某石膏矿为例,介绍了利用存在地层倒转、地层缺失等复杂钻孔数据进行三维建模的流程以及模型建立后的三维空间分析方法和地学应用,尝试了三维GIS空间-属性查询、空间裁剪、纵剖面横切面的自动生成方法和实例研究.结果表明,地质体和构造的特征的三维建模和空间分析有利于地质演化的理解和开采设计的优化.     

Three-dimensional mineral prospectivity modeling for targeting of concealed mineralization within the Zhonggu iron orefield,Ningwu Basin,China

The Zhonggu iron orefield is one of the most important iron orefields in China, and is located in the south of the Ningwu volcanic basin, within the middle and lower Yangtze metallogenic belt of eastern China. Here, we present the results of new 3D prospectivity modeling that enabled the delineation of areas prospective for exploration of concealed and deep-seated Baixiangshan-type mineralization and Yangzhuang-type mineralization within the Zhonggu orefield; both of these deposits are Kiruna-type Fe-apatite deposits but are hosted by different formations within the Ningwu Basin. The modeling approach used during this study involves 3 steps: (1) combining available geological and geophysical data to construct 3D geological models; (2) generation of 3D predictive maps from these 3D geological models using 3D spatial analysis and 3D geophysical methods; (3) combining all of the 3D predictive maps using logistic regression to create a prospectivity map. This approach integrates a large amount of available geoscientific data using 3D methods, including 3D geological modeling, 3D/2D geophysical methods, and 3D spatial analysis and data integration methods. The resulting prospectivity model clearly identifies highly prospective areas that not only include areas of known mineralization but also a number of favorable targets for future mineral exploration. The 3D prospectivity modeling approach showcased within this study provides an efficient way to identify camp-scale concealed and deep-seated exploration targets and can easily be adapted for regional- and deposit- scale targeting.     

水利工程信息模型:方法、框架与应用

三维信息化模型是重大工程全生命周期建设的重要基础。然而,目前对于地质三维模型与建筑结构三维信息模型,通常由于数据结构问题难以统一,而且大部分停留在“可视化”,难以“可计算”、“可分析”。此外,由于地质条件的复杂性,在三维地质建模方面通常进行大量的简化。本文基于目前先进的三维建模技术,提出了三维精细化地质模型与建筑结构三维模型融合的建模方法,实现了三维地质模型的快速、精细化建模。所建立的模型,统一在*.stl、*.obj及*.igs等标准化三维模型文件下,可方便地用于不同场景的三维模型可视化、分析及后续数值计算模型网格划分等。针对大型水电工程建设提出了水利工程信息模型的框架,并将其应用于索风营水利工程,实现了大坝精细化BIM及4个堆积体的精细化三维地质模型(LIM)的融合与信息化管理。本文研究对于实现水电工程信息化管理、稳定性分析、潜在灾害评估和预测等具有重要的意义。     

三维成矿预测数据整合过程不确定性研究——以宁芜盆地钟姑矿田为例

基于多元地学大数据的三维成矿预测方法是开展深部找矿预测的新方法和新手段,也是当前成矿预测领域的研究热点之一。然而,大数据具有高维、混杂、非精确等特点,其分析处理过程面临多重不确定性。多元地学大数据整合是三维成矿预测的最终环节,其存在的不确定性将直接作用于预测结果,影响进一步的找矿应用和风险评估。本文以宁芜盆地钟姑矿田为例,从大数据思维出发,定量分析和度量预测要素和数学模型在数据整合过程中存在的不确定性及对三维成矿预测结果的影响。结果显示,断裂构造、背斜轴部等预测要素的不确定性对三维成矿预测结果的影响最为强烈;数据整合模型中,较之Logistic回归模型和证据权重模型,神经网络模型可能具有更高的不确定性程度。进一步工作可通过增强上述预测要素的可靠性和有效性、采用更多的数据整合模型进行更为全面的不确定性分析和评价,以获得更为可靠的三维成矿预测成果,从而降低成矿预测和找矿勘探风险。     

基于精细岩相约束的致密低渗储层参数建模研究——以红河油田92井区长812致密砂岩储层为例

鄂尔多斯盆地红河油田属于低孔、超低渗岩性油气藏.红河油田长8储层主要发育辫状河三角洲前缘水下分流河道和分流间湾两种沉积微相,并且在水下分流河道沉积微相中储层参数变化范围大,非均质性强,用常规的单一沉积相控建模方法无法对储层参数空间分布的非均质性进行充分表征.为了精确描述其储层参数及展布特征,以红河油田92井区长8₁²致密砂岩储层为例,在地质、岩心、测井等资料的基础上,应用基于精细岩相约束的储层参数建模方法建立了研究区三维地质模型,即先用沉积相发育模式约束建立沉积微相模型,再对水下分流河道沉积微相进行岩相细分,在沉积微相模型和不同岩相概率体的双重控制下建立岩相模型,然后以岩相模型为约束建立储层参数模型.结果表明,该方法建立的储层参数模型具有较高的可靠性,与地质认识符合较好,为该区油藏数值模拟提供了精确的地质模型,并为研究区下一步开发方案调整提供了地质依据.     

Geothermal reservoirs — A brief review

A brief discussion and review of the geothermal reservoir systems, geothermal energy and modeling and simulation of the geothermal reservoirs has been presented here. Different types of geothermal reservoirs and their governing equations have been discussed first. The conceptual and numerical modeling along with the representation of flow though fractured media, some issues related to non isothermal flow through fractured media, the efficiency of the geothermal reservoir, structure of the numerical models, boundary conditions and calibration procedures have been illustrated. A brief picture of the Indian scenario and some barriers related with geothermal power are discussed and presented thereafter. Finally some gaps of the existing knowledge and recent focuses of research are discussed.     

Integrated geothermal modeling on different scales in the Northeast German basin

Geothermal modeling is an important part of large-scale basin studies. Based on a new 3D structural model of the Northeast German basin, the present day regional geothermal field is modeled. Range and regional trend of the modeled temperature values are in agreement with the published data. Due to the high spatial resolution, the calculated temperature distribution provides additional information with respect to areas where no measured data is available. The results are used as input and boundary parameters for small-scale models of geothermal energy production. In general, in many regions not enough data is available to define all necessary physical or chemical parameters for modeling. In this context, data obtained from the large-scale model help to constrain unknown parameters. Subsequently, the small-scale model is used to simulate various production schemes focusing on enhanced predictions with respect to the possible lifetime of such installations. The simulation results also show the need for elaborated models if reliable predictions of the temperature evolution are required.     

Fast FILTERSIM Simulation with Score-based Distance

FILTERSIM is a pattern-based multiple-point geostatistical algorithm for modeling both continuous and categorical variables. It first groups all the patterns from a training image into a set of pattern classes using their filter scores. At each simulation location, FILTERSIM identifies the training pattern class closest to the local conditioning data event, then samples a training pattern from that prototype class and pastes it onto the simulation grid. In the original FILTERSIM algorithm, the selection of the closest pattern class is based on the pixel-wise distance between the prototype of each training pattern class and the local conditioning data event. Hence, FILTERSIM is computationally intensive for 3D simulations, especially with a large and pattern-rich training image. In this paper, a novel approach is proposed to accelerate the simulation process by replacing that pixel-wise distance calculation with a filter score comparison, which is the difference between the filter score of local conditioning data event and that of each pattern prototype. This score-based distance calculation significantly reduces the CPU consumption due to the tremendous data dimension reduction. The results show that this new score based-distance calculation can speed up FILTERSIM simulation by a factor up to 10 in 3D applications.     

地震储层表征:在模拟储层的三维地震响应时考虑盖层、地震勘探布局和储层物性的敏感度

根据三维地震地质模型对地震数据进行模拟是从勘探到生产的周期内决策过程中的一个不可或缺的组成部分。虽然对于在储层内的动力过程和地震地质的模型表述已经取得很大进展,但如何从这些模型得到地震数据的精确模拟仍面临很多挑战。通常是在地球模型范围内根据物性用一维褶积方法来模拟地震数据。然而这个过程一般不考虑地震勘探布局和盖层对地震信号的影响。我们审视了为什么这些因素会制约三维地球模型的有效性,并考虑了为什么需要把盖层和地震勘探布局对三维覆盖和分辨率的影响加进模拟过程之中。我们提出了一种新方法,把建立物性模型和一种新的地震模拟技术结合起来,给出一个工作流程;利用这个流程,勘探工作者可以很快模拟出三维的PSDM数据,这些数据加进了盖层和地震勘探布局对覆盖及分辨率的影响。我们利用从远离挪威海岸的一个油田得到的数据,在考虑覆盖和分辨率效应的地震数据模拟之前,对岩石物性做了一些扰动,然后进行地震数据模拟,以此来说明如何可以用这种方法提高三维地球模型的精确性和增进我们对储层的了解。     

一种基于似三棱柱体元的地质三维建模方法研究

三堆空间建模方法是三堆地劫工程GIS研究的核心问题之一。提出一种基于似三棱柱体元的三堆数据模型，模型包含顶点、线段(棱边、三角形边)、三角形、侧面四边形、三棱柱体元5个基本元素。和点对象、线对象、面对象、体对象、复杂对象、空间对象等6个对象。设计了5个基本元素和3种地质对象的数据结构和它们之间的拓扑关系。以岩体和巷道为例。给出了似三棱柱体建模思路和算法。利用内蒙古某矿区实际钻孔资料和模拟巷道数据对所开发的系统原型进行验证。研究表明。基于似三棱柱体元的数据模型的优势在于可以表示空间对象的表面和内部结构。便于建模和节省存储空间，同时便于不规劓的自然地质体和规则勘探工程建模。     

基于ArcGIS ModelBuilder的复杂地质体自动建模方法

与传统的二维（2D）地质绘图技术相比,三维地质建模技术能够更加直观、立体地展现地下岩层的结构和空间分布情况,在工程的规划、设计、施工和风险评估等过程都具有重要的应用价值。针对工程领域的建模对象往往涉及复杂地质体,为实现模型的自动构建,本文提出一种基ArcGIS ModelBuilder的复杂地质体自动建模方法。首先,在ArcGIS平台的支持下,以钻孔数据和地质剖面图为数据源,采用面向对象编程Python语言结合ArcPy包,通过编程实现钻孔数据的自动预处理;其次,组合ArcScan自动矢量化和SkechUp人机交互对地质剖面进行预处理,从中提取出断裂3D矢量线,将它们集中存储于GIS空间数据库;然后,利用ModelBuilder可视化建模工具,通过调用ArcToolbox的文件转换和空间分析工具分别生成地层的三维实体模型和断裂的三维表面模型,从而实现复杂地质体自动建模;进一步,通过矢量化切割、剖面和开挖多边形作为TIN拉伸扩展工具的输入,并结合ArcScene实现模型多种形式的可视化。最后,采用南京仙林地区三维地质调查项目获取的钻孔数据进行了建模实验,建模结果表明:该方法具有准确、快速和自动化的优势,可为大范围、大批量地质建模提供可靠的技术方案。     

Modeling seawater intrusion in overexploited aquifers in the absence of sufficient data: application to the aquifer of Nea Moudania,northern Greece

In many coastal areas, overexploitation of groundwater resources has led both to the quantitative degradation of local aquifers and the deterioration of groundwater quality due to seawater intrusion. To investigate the behavior of coastal aquifers under these conditions, numerical modeling is usually implemented; however, the proper implementation of numerical models requires a large amount of data, which are often not available due to the time-consuming and costly process of obtaining them. In the present study, the investigation of the behavior of coastal aquifers under the lack of adequate data is attempted by developing a methodological framework consisting of a series of numerical simulations: a steady-state, a false-transient and a transient simulation. The sequence and the connection between these simulations constitute the backbone of the whole procedure aimed at adjusting the various model parameters, as well as obtaining the initial conditions for the transient simulation. The validity of the proposed methodology is tested through evaluation of the model calibration procedure and the estimation of the simulation errors (mean error, mean absolute error, root mean square error, mean relative error) using the case of Nea Moudania basin, northern Greece. Furthermore, a sensitivity analysis is performed in order to minimize the error estimates and thus to maximize the reliability of the models. The results of the whole procedure affirm the proper implementation of the developed methodology under specific conditions and assumptions due to the lack of sufficient data, while they give a clear picture of the aquifer’s quantitative and qualitative status.     

一种面向对象的三维地下空间矢量数据模型

针对地下空间的真三维连续特性以及建模过程的动态交互编辑与分析要求,提出了一种新的三维地下空间矢量数据模型。该模型采用面向对象思想对地下各种空间对象进行抽象描述;利用模型中的线段要素增强几何元素之间拓扑连接关系的维持,为地质体的切割和地下工程体的开挖等分析提供了算法上的便利;引入拓扑面更好地表达了地下空间对象之间的拓扑邻接关系。该模型在三维地下空间数据的存储管理、查询分析以及实时逼真绘制等方面都表现出较好的性能,适用于地下勘探工程的建模与分析。     

一种基于交叉剖面的地质模型构建方法

针对基于近似平行断面数据的建模方法的缺点,利用交叉地质剖面数据,提出了一种通过划分空间单元格的思路来构建地质结构模型的方法。该方法基于“分而自治”的思想,将复杂的整体的建模区域划分为单个单元格内的建模,待每个格子内的建模完成之后,采用相反的思路,将所有格子内的模型拼接起来形成最终的建模区域内的整体模型