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1.
Topology has been used to characterise and quantify the properties of complex systems in a diverse range of scientific domains. This study explores the concept and applications of topological analysis in geology. We have developed an automatic system for extracting first order 2D topological information from geological maps, and 3D topological information from models built with the Noddy kinematic modelling system, and equivalent analyses should be possible for other implicit modelling systems. A method is presented for describing the spatial and temporal topology of geological models using a set of adjacency relationships that can be expressed as a topology network, thematic adjacency matrix or hive diagram. We define three types of spatial topology (cellular, structural and lithological) that allow us to analyse different aspects of the geology, and then apply them to investigate the geology of the Hamersley Basin, Western Australia. 相似文献
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3D geological models are created to integrate a set of input measurements into a single geological model. There are many problems with this approach, as there is uncertainty in all stages of the modelling process, from initial data collection to the approach used in the modelling scheme itself to calculate the geological model. This study looks at the uncertainty inherent in geological models due to data density and introduces a novel method to upscale geological data that optimises the information in the initial dataset. This method also provides the ability for the dominant trend of a geological dataset to be determined at different scales. By using self-organizing maps (SOM's) to examine the different metrics used to quantify a geological model, we allow for a larger range of metrics to be used compared to traditional statistical methods, due to the SOM's ability to deal with incomplete datasets. The classification of the models into clusters based on the geological metrics using k-means clustering provides a useful insight into the models that are most similar and models that are statistical outliers. Our approach is guided and can be calculated on any input dataset of this type to determine the effect that data density will have on a resultant model. These models are all statistical derivations that represent simplifications and different scales of the initial dataset and can be used to interrogate the scale of observations. 相似文献
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Uncertainties in Facies Proportion Estimation II: Application to Geostatistical Simulation of Facies and Assessment of Volumetric Uncertainties 总被引：1，自引：0，他引：1
Geostatistical simulations of lithotypes or facies are commonly used to create a geological model and to describe the heterogeneities of petroleum reservoirs. However, it is difficult to handle such models in the framework of multiple realizations to assess the uncertainty of hydrocarbon in place. Indeed, the hydrocarbon in place is correlated with the facies proportions, which are themselves uncertain. The uncertainty model of facies proportions is not easy to describe because of closure relationships. A previous attempt was made with a nonparametric approach using the resampling technique. It has been successful in a stationary case but it is difficult to extend it to nonstationary cases. In this paper, we have applied the vectorial beta parametric model or Dirichlet model. It has provided much more realistic uncertainties on volumetrics in very different geological and geostatistical contexts. 相似文献
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We present a general framework that enables decision-making when a threshold in a process is about to be exceeded (an event).
Measurements are combined with prior information to update the probability of such an event. This prior information is derived
from the results of an ensemble of model realisations that span the uncertainty present in the model before any measurements
are collected; only probability updates need to be calculated, which makes the procedure very fast once the basic ensemble
of realisations has been set up. The procedure is demonstrated with an example where gas field production is restricted to
a maximum amount of subsidence. Starting with 100 realisations spanning the prior uncertainty of the process, the measurements
collected during monitoring bolster some of the realisations and expose others as irrelevant. In this procedure, more data
will mean a sharper determination of the posterior probability. We show the use of two different types of limits, a maximum
allowed value of subsidence and a maximum allowed value of subsidence rate for all measurement points at all times. These
limits have been applied in real world cases. The framework is general and is able to deal with other types of limits in just
the same way. It can also be used to optimise monitoring strategies by assessing the effect of the number, position and timing
of the measurement points. Furthermore, in such a synthetic study, the prior realisations do not need to be updated; spanning
the range of uncertainty with appropriate prior models is sufficient. 相似文献
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This paper presents robust algorithms for application in polyhedral modelling of rock mass structure based on discrete fracture networks. The algorithms improve the robustness of current polyhedral modellers to challenging or degenerate geometries and geometrical errors. These issues are inevitably encountered when the fracture network realisations incorporate large numbers of fractures, or regions of densely packed fractures are modelled, or when the number of fracture network realisations interrogated is large. Several stages in the polyhedral modelling process which are sensitive to geometrical errors are reviewed and algorithms which are robust and capable of handling topological errors in the input fracture network geometry are presented. 相似文献
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由于地质体存在断层、尖灭、出露等复杂地质现象,在三维地层建模时,为了表达这些现象,无论是面模型还是体模型或混合模型,都存在空间分割或曲面求交线的问题。由于地质体拓扑关系的复杂性、数据误差以及计算机精度问题,使得这些模型在实际建模过程中常常失效。运用水平集理论可以有效解决这一问题,水平集用隐函数表达曲面（或超曲面）,可以实现复杂地质体的表达及并、交、差等拓扑运算。在三维地层建模中,插值生成各种地质界面后,用水平集表达这些地质界面,利用水平理论完成各种复杂的拓扑操作,建立以水平集表达的三维地层模型。在此基础上,插入水平集表达的各种工程活动界面,利用水平集理论进行拓扑操作,可构建各种工程活动后的地层模型。再利用Marching cube算法抽取各种地质界面或工程活动界面,构建可用于实时可视化或用于工程评估（如有限元计算）等的NMTINF-BR地层模型或工程活动后的NMTINF-BR地层模型。 相似文献
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针对目前常用的储层地质模型不确定性评价方法存在的主要问题,提出了先用距离函数计算模型之间的差异,再以差异的大小来判断不确定性大小的方法.以WZ油田西区为例,采用相控物性参数建模技术,利用顺序高斯模拟方法建立渗透率的三维模型.对各种度量差异的距离函数进行对比研究和分析,结果显示曼哈顿距离函数和欧氏距离函数能较好地刻画模型之间的差异.选用欧氏距离函数计算模型之间的差异,其原理是先计算每两个模型之间相对应的每一网格节点的渗透率值差的平方和,然后取平方根,得到一个表征各模型之间差异的矩阵.根据该矩阵可得到各个模型之间的差异程度,差异越大,不确定性就越大.最后通过对比模型过井剖面图分析结果与距离矩阵分析结果,说明了本方法的正确性,结果显示该方法能有效评价随机模拟生成的储层地质模型的不确定性. 相似文献
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B. Miles T. Kalbacher O. Kolditz C. Chen J. Gronewold W. Wang A. Peter 《Environmental Geology》2007,52(7):1399-1412
Ongoing developments in geological and hydrogeological investigation techniques, especially direct-push methods, have led
to an increase in the quality, density and spatial resolution of data available from such investigations. This has created
new challenges in the development of numerical models in terms of accurately and efficiently translating detailed and complex
conceptual models into effective numerical models. Suitable geometrical and numerical modelling tools are essential in order
to meet these challenges. This paper describes the development of a three-dimensional hydrogeological flow model for a contaminated
site near Berlin, Germany, based on high-resolution geological data obtained principally using direct-push methods. The available
data were first interpreted to construct a detailed GIS-based geological model, which formed the basis of the conceptual site
model. The conceptual model was then translated into a geometrical model, which was used to create a finite element numerical
model. An innovative geometry object-based approach enabled the complex structural details of the conceptual model to be accurately
reproduced in the numerical model domain. The resulting three-dimensional steady-state unconfined flow model was successfully
calibrated using external automated calibration software, whereby parameter values for groundwater recharge and hydraulic
conductivity were determined. 相似文献
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针对地质环境中不同断层构造出现交叉、削截等现象而构成的复杂断层网络,本文基于隐函数曲面重建提出了一种三维断层网络隐式建模方法。该方法首先以径向基隐函数曲面重建理论为基础,基于地质剖面图中断层轮廓线数据以及断层产状信息隐式构建三维断层面模型;然后使用二叉树结构描述不同断层间的空间拓扑关系构建断层网络模型;最后,考虑断层建模中产状信息估计的不确定性,定义了断层面法向量概率分布模型,采用信息熵指标定量评价断层模型质量。以贵州水银洞金矿床为实例矿床,选定包含多条断层的区域作为试验区,采用该方法构建了实例三维断层网络模型,结果表明,基于隐函数曲面的三维断层网络建模方法能快速构建区域内多条断层的三维断层网络模型和拓扑结构,有助于复杂断层网络快速建模和三维形态分析,为断层构造定量研究提供基础。 相似文献
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3D structural modeling is a major instrument in geosciences, e.g. for the assessment of groundwater and energy resources or nuclear waste underground storage. Fault network modeling is a particularly crucial step during this task, for faults compartmentalize rock units and plays a key role in subsurface flow, whether faults are sealing barriers or drains. Whereas most structural uncertainty modeling techniques only allow for geometrical changes and keep the topology fixed, we propose a new method for creating realistic stochastic fault networks with different topologies. The idea is to combine an implicit representation of geological surfaces which provides new perspectives for handling topological changes with a stochastic binary tree to represent the spatial regions. Each node of the tree is a fault, separating the space in two fault blocks. Changes in this binary tree modify the fault relations and therefore the topology of the model. 相似文献
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In this paper, a random Cellular Automaton model is developed to characterise heterogeneity of geological formations. The
CA-model is multilateral and can be easily applied in both two and three dimensions. We demonstrate that conditioning on well
data is possible and the method is numerically efficient. To construct the model, the subsurface is subdivided into N cells, with an initial lithology assigned to each cell. Rules to update the current cell states are chosen from a set of
rules, independently for each cell. The model converges typically in less than 50 iterations to a steady state or periodic
solution. Within one period the realisations exhibit similar statistical properties. The final fraction of the various lithologies
can be tuned by choosing the proper initial fractions. In this way, geological knowledge of those fractions can be satisfied. 相似文献
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《地学前缘(英文版)》2022,13(6):101435
The past two decades have seen a rapid adoption of artificial intelligence methods applied to mineral exploration. More recently, the easier acquisition of some types of data has inspired a broad literature that has examined many machine learning and modelling techniques that combine exploration criteria, or ‘features’, to generate predictions for mineral prospectivity. Central to the design of prospectivity models is a ‘mineral system’, a conceptual model describing the key geological elements that control the timing and location of economic mineralisation. The mineral systems model defines what constitutes a training set, which features represent geological evidence of mineralisation, how features are engineered and what modelling methods are used. Mineral systems are knowledge-driven conceptual models, thus all parameter choices are subject to human biases and opinion so alternative models are possible. However, the effect of alternative mineral systems models on prospectivity is rarely compared despite the potential to heavily influence final predictions. In this study, we focus on the effect of conceptual uncertainty on Fe ore prospectivity models in the Hamersley region, Western Australia. Four important considerations are tested. (1) Five different supergene and hypogene conceptual mineral systems models guide the inputs for five forest-based classification prospectivity models model. (2) To represent conceptual uncertainty, the predictions are then combined for prospectivity model comparison. (3) Representation of three-dimensional objects as two-dimensional features are tested to address commonly ignored thickness of geological units. (4) The training dataset is composed of known economic mineralisation sites (deposits) as ‘positive’ examples, and exploration drilling data providing ‘negative’ sampling locations. Each of the spatial predictions are assessed using independent performance metrics common to AI-based classification methods and subjected to geological plausibility testing. We find that different conceptual mineral systems produce significantly different spatial predictions, thus conceptual uncertainty must be recognised. A benefit to recognising and modelling different conceptual models is that robust and geologically plausible predictions can be made that may guide mineral discovery. 相似文献
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An accurate estimation of mineral grades in ore deposits with heterogeneous spatial variations requires defining geological domains that differentiate the types of mineralogy, alteration and lithology. Deterministic models define the layout of the domains based on the interpretation of the drill holes and do not take into account the uncertainty in areas with fewer data. Plurigaussian simulation (PGS) can be an alternative to generate multiple numerical models of the ore body, with the aim of assessing the uncertainty in the domain boundaries and improving the geological controls in the characterization of quantitative attributes. This study addresses the application of PGS to Sungun porphyry copper deposit (Iran), in order to simulate the layout of four hypogene alteration zones: potassic, phyllic, propylitic and argillic. The aim of this study is to construct numerical models in which the alteration structures reflect the evolution observed in the geology. 相似文献
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Lars Troldborg Jens Christian Refsgaard Karsten Høgh Jensen Peter Engesgaard 《Hydrogeology Journal》2007,15(5):843-860
Four different conceptual models based on alternative geological interpretations were formulated for a shallow 600 km2 aquifer system in Denmark comprising Quaternary deposits. Each of the four models was calibrated against groundwater heads and discharge measurements through inverse modeling. Subsequently, the transport capabilities of the four models were compared to 32 concentration measurements of environmental tracers (tritium 3H, helium-3 3He, chlorofluorocarbons CFC11, CFC12 and CFC113). The flow simulations showed only minor differences in spatial head distribution associated with alternative conceptualizations despite the complexity of the aquifer system and the significant differences in geological interpretations. The models, however, showed major differences in predictions of the age of the groundwater and environmental tracer concentrations, differences that are seen as an effect of model structure uncertainty, because no additional calibrations to these data were performed. A single conceptualization may be adequate in characterizing the natural behavior of a field system after calibration, because the calibration procedure is able to compensate for errors in the data or in the conceptual model through biased parameter values. However, once extrapolation beyond the calibration base is attempted, different conceptual model formulations result in significantly different results. Consequently, it is crucial to take model conceptual uncertainty into account when making predictions beyond the calibration base. 相似文献
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本文基于华东院自主研发的GeoStation地质三维勘察设计系统,设计一种城市片区地质三维建模技术方法。该方法首先采用地质剖面作为地质拓扑剖面,其次使用地质拓扑剖面将城市片区划分为若干城市区块,再次使用GeoStation系统的地层自动建模功能独立构建城市区块模型,最后将城市区块拼合为整体模型。该方法集成在GeoStation系统中,并在某城市级BIM应用中进行应用,结果表明该技术方法可行,实现了海量庞杂地质建模数据的高效管理,构建的地质三维模型可满足某城市BIM平台数据要求,为城市地理空间信息建模提供新的手段,也为其他城市开展数字化建设和智慧化管理提供范例。 相似文献
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Although the definitions of formal models used to represent spatial relations have gained increasing attention over the past 30 years, the linkage between topology and distance has not yet been effectively established. A topological relation model called the distance-based topological relation model (D-TRM) that considers both the topology and distance of spatial regions is proposed. The D-TRM is divided into two subtypes: the actual DTRM (AD-TRM) and the signed DTRM (SD-TRM). The actual distance is based on the distance in a two-dimensional space. The signed distance is based on the sign of the actual distance. Eight topological relations, namely, disjoint, meet, overlap, cover, contain, equal, coveredBy and inside, represented by the AD-TRM and SD-TRM are shown. The mutual exclusiveness among these eight topological relations represented by the SD-TRM is proven. The topological relation representations from the 9-intersection model (9IM), the splitting measures of the 9IM (SP-9IM), the SD-TRM and the AD-TRM are discussed, and the interoperability of each of the above models is summarised. The topological relation representation between the AD-TRM and the comprehensive set of 11 metric refinements is compared. The results show the following: (1) as the generalisation of the AD-TRM, the SD-TRM can concisely represent the topological relations; (2) the topology and distance between two spatial regions can be represented by the AD-TRM in a unified framework; (3) the AD-TRM provides a greater level of detail than the 9IM and (4) the D-TRM can express more distance information than the comprehensive set of 11 metric refinements. 相似文献
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The presence of geological units with different grade characteristics mostly leads to problems during the grade modeling process. In special cases, if the area under study has units with small thickness and low grade with respect to the dominant unit of the area, it is difficult to reproduce different grade contents in these units in the simulated grade models because of the low thickness and lack of data in these units. In this study, the local moment constraints method, based on the definition of soft conditioning data reflecting geological knowledge, is investigated for improving simulated grade models under the mentioned conditions. This method is applied for grade simulation at the 1,750 m level of Sungun porphyry copper mine. The studied area is divided into two rock type domains: Sungun porphyry and Dyke. The Sungun porphyry unit is the dominant rock type in the considered area and has, on average, a higher copper grade, while dykes discontinue Sungun porphyry rock units sporadically and most of them are barren of mineralization. It is demonstrated that the use of soft conditioning data makes the simulated grade model closer to reality and improves the reproduction of grade contents considering the rock type units in the area. In the next step, the results obtained from conditional simulation are used for mineral resources classification. To this end, the conditional coefficient of variation is chosen as a criterion for measuring uncertainty and for defining the resources classes. Then, it is shown that uncertainty can be considerably reduced in the prepared models if soft data are considered; as a result, an increase in measured resource classification is observed. 相似文献