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1.
J. Athersuch F. T. Banner A. C. Higgins R. J. Howarth P. A. Swaby 《Mathematical Geology》1994,26(4):483-489
Development of an expert system for microfossil identification and their use in dating rocks demonstrates that such systems can be used in the evaluation and interpretation of basic geological data. Palaeontological data lends itself to this kind of approach because it is controlled to a greater extent than other geological data by internationally accepted rules and practice. Two fossil groups, planktonic foraminifera and conodonts, have been chosen for initial development, both groups having a long history of study. 相似文献
2.
Uncertainty is ubiquitous in geology, and efforts to characterise and communicate it are becoming increasingly important. Recent studies have quantified differences between perturbed geological models to gain insight into uncertainty. We build on this approach by quantifying differences in topology, a property that describes geological relationships in a model, introducing the concept of topological uncertainty. Data defining implicit geological models were perturbed to simulate data uncertainties, and the amount of topological variation in the resulting model suite measured to provide probabilistic assessments of specific topological hypotheses, sources of topological uncertainty and the classification of possible model realisations based on their topology. Overall, topology was found to be highly sensitive to small variations in model construction parameters in realistic models, with almost all of the several thousand realisations defining distinct topologies. In particular, uncertainty related to faults and unconformities was found to have profound topological implications. Finally, possible uses of topology as a geodiversity metric and validation filter are discussed, and methods of incorporating topological uncertainty into physical models are suggested. 相似文献
3.
成矿过程是一个复杂的物理化学过程,由于地质自身的不确定性、原始数据采集和处理的不当、预测方法中经验参数的不确定性等多重因素的叠加,造成矿产资源定量预测结果中潜在大量不确定性。在科学认识这些不确定性的基础上,如何降低不确定性是预测评价研究的一个重要方向。以地质异常理论和成矿动力学为指导,双向预测评价方法是降低地质异常分析中不确定性的有效途径,该方法具体包括基于矿床成因模型的成矿模拟和基于找矿模型与勘查数据相结合的模型驱动预测。前者作为研究成矿地质演化过程、探讨成矿动力学机制的定量化方法之一,可以直观展示成矿过程内部物理化学变化。作为对致矿地质异常分析的有效手段,通过将成矿过程抽象为不受时空间限制的可迭代计算的偏微分方程组,可实现定量化描述复杂成矿动态过程并预测成矿有利部位。通过挖掘成矿有利信息,分析地质变量并赋值,为预测模型提供大量的定量化预测变量和特征值,是矿产资源定量预测评价的一个最具潜力的发展方向。后者以勘查学为指导的矿化异常分析,从矿致地质异常的角度开展定量预测,减少了单一成矿有利信息的多解性并降低了预测结果的不确定性。该技术手段是依托空间数据库、地质统计学和地理信息系统空间分析技术支撑,以三维地质体模型的建立为基础,以分析成矿规律并建立找矿模型为核心工作内容,以证据权、找矿信息量等数学方法为工具,统计分析研究区内各地质要素单元的分布情况来探讨各地质要素对矿产预测的影响,最终实现基于“立方体预测模型”的定位、定量和定概率的隐伏矿体三维预测目标。以上方法从两种不同的地质角度和定量化理念创新性地实现了双向联合预测评价,两种技术手段的融合作为综合圈定“5P”找矿地段的数学地质方法,其作用和价值是相互补充并有机结合的。通过文中方法介绍和应用实例的研究成果,可以明确该方法确实提高了矿产资源定量预测评价的预测精度,一定程度上降低了预测的不确定性,整体上推动了地球科学研究由定性描述向定量化自然科学的转变。 相似文献
4.
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。 相似文献
5.
The uncertainty in the recoverable tonnages and grades in a mineral deposit is a key factor in the decision-making process of a mining project. Currently, the most prevalent approach to model the uncertainty in the spatial distribution of mineral grades is to divide the deposit into domains based on geological interpretation and to predict the grades within each domain separately. This approach defines just one interpretation of the geological domain layout and does not offer any measure of the uncertainty in the position of the domain boundaries and in the mineral grades. This uncertainty can be evaluated by use of geostatistical simulation methods. The aim of this study is to evaluate how the simulation of rock type domains and grades affects the resources model of Sungun porphyry copper deposit, northwestern Iran. Specifically, three main rock type domains (porphyry, skarn and late-injected dykes) that control the copper grade distribution are simulated over the region of interest using the plurigaussian model. The copper grades are then simulated in cascade, generating one grade realization for each rock type realization. The simulated grades are finally compared to those obtained using traditional approaches against production data. 相似文献
6.
7.
在分析地质标准物质标准值不确定度来源的基础上,提出了在多个实验室协作研制地质标准物质时,协作单位除提供重现性检测数据外,还应分别提供各项目检测数据的合成不确定度。分析方法或实验室之间的平均值的合成不确定度按不等精度方法处理。标准物质标准值的不确定度由分析方法、检测实验室、样品均匀性和样品稳定性的不确定度合成后乘以扩展不确定度置信水平下的包含因子而得。 相似文献
8.
Using Sequential Indicator Simulation as a Tool in Reservoir Description: Issues and Uncertainties 总被引：3，自引：0，他引：3
Flow simulation studies require an accurate model of the reservoir in terms of its sedimentological architecture. Pixel-based reservoir modeling techniques are often used to model this architecture. There are, however, two problem areas with such techniques. First, several statistical parameters have to be provided whose influence on the resulting model is not readily inferable. Second, conditioning the models to relevant geological data that carry great uncertainty on their own adds to the difficulty of obtaining reliable models and assessing model reliability. The Sequential Indicator Simulation (SIS) method has been used to examine the impact of such uncertainties on the final reservoir model. The effects of varying variogram types, frequencies of lithology occurrence, and the gridblock model orientation with respect to the sedimentological trends are illustrated using different reservoir modeling studies. Results indicate, for example, that the choice of variogram type can have a significant impact on the facies model. Also, reproduction of sedimentological trends and large geometries requires careful parameter selection. By choosing the appropriate modeling strategy, sedimentological principles can be translated into the numerical model. Solutions for dealing with such issues and the geological uncertainties are presented. In conclusion, each reservoir modeling study should begin by developing a thorough quantitative sedimentological understanding of the reservoir under study, followed by detailed sensitivity analyses of relevant statistical and geological parameters. 相似文献
9.
《地学前缘(英文版)》2023,14(2):101521
Lithofacies paleogeography is a data-intensive discipline that involves the interpretation and compilation of sedimentary facies. Traditional sedimentary facies analysis is a labor-intensive task with the added complexity of using unstructured knowledge and unstandardized terminology. Therefore, it is very difficult for beginners or non-geology scholars who lack a systematic knowledge and experience in sedimentary facies analysis. These hurdles could be partly alleviated by having a standardized, structured, and systematic knowledge base coupled with an efficient automatic machine-assisted sedimentary facies identification system. To this end, this study constructed a knowledge system for fluvial facies and carried out knowledge representation. Components include a domain knowledge graph for types of fluvial facies (meandering, braided and other fluvial depositional environments) and their characteristic features (bedforms, grain size distribution, etc.) with visualization, a method for query and retrieval on a graph database platform, a hierarchical knowledge tree-structure, a data-mining clustering algorithm for machine-analysis of publication texts, and an algorithm model for this area of sedimentary facies reasoning. The underlying sedimentary facies identification and knowledge reasoning system is based on expert experience and synthesis of publications. For testing, 17 sets literature publications data that included details of sedimentary facies data (bedforms, grain sizes, etc.) were submitted to the artificial intelligence model, then compared and validated. This testing set of automated reasoning results yielded an interpretation accuracy of about 90% relative to the published interpretations in those papers. Therefore, the model and algorithm provide an efficient and automated reasoning technology, which provides a new approach and route for the rapid and intelligent identification of other types of sedimentary facies from literature data or direct use in the field. 相似文献
10.
本文从油气藏地质成因分析的基础资料入手,总结该项研究的主要内容包括:构造、储层和油气水分布特征等3方面.结合自身科研实践,认为油气藏地质成因分析方法主要包括:野外露头和现代沉积考察、岩心观察描述、显微镜下薄片观察鉴定、地球物理解释预测、地质统计学分析、分析测试、各种物理模拟和数值模拟、油气藏动态监测和生产动态等,并阐述了不同研究方法的优缺点.目前油气藏地质成因分析存在的主要问题包括:对油气藏地质成因分析重视程度不够、研究方法偏定性、地质成因分析和油气藏表征结合不紧密、油气藏表征精度制约了地质成因分析的准确度、油气藏地质成因分析综合性不强、特殊类型油气藏地质成因分析还存在诸多难题等.本文指出了该研究未来发展方向.主要包括:依靠油气藏地质成因分析解决油气田开发中的难题、通过各种模拟方法提高油气藏地质成因分析定量化水平、加强地质成因分析以提高油气藏表征水平、利用油气藏表征促进地质成因分析进步、拓展油气藏地质成因分析在油气田开发中应用的领域、特殊类型油气藏地质成因分析等. 相似文献
11.
The ion microprobe, as exemplified by SHRIMP, has long been an invaluable resource for the derivation of geological ages. The derivation of those ages is critically dependent on the identification and individual quantification of all sources of contributing uncertainty. In recent years, it has been proposed that the only component of uncertainty arising from the instrument itself is predictable from counting statistics. The adoption of that approach has led to several conclusions including: (i) that zircon U–Pb ages are relatively easily reset, which necessitates the enhanced editing of individual analyses before a grouped age can be obtained; and (ii) that other studies have overestimated analytical uncertainties and, as a consequence, have reported incorrect and/or overly imprecise ages. We present evidence for the presence of additional sources of instrument‐related uncertainty that necessitates a different (but not new) approach for the processing of SHRIMP data. Fortunately, this complication does not represent a serious problem, provided that a high‐quality zircon‐calibration standard has been used for Pb/U calibration. SHRIMP ages obtained some time ago from the Crudine Group of the Hill End Trough (New South Wales) have recently been placed at the centre of this controversy. A significant part of the problem is that most of those ages were based on a standard (SL 13) that is now known to be heterogeneous. The more reliable parts of the original data have been re‐reprocessed on the basis of the new evidence. They fail to detect a significant age difference between the bottom and the top of the Merrions Formation, a conclusion that is contrary to earlier expressed opinions. 相似文献
12.
Gregory B. Baecher 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2016,10(2):92-108
The character and importance of uncertainty in dam safety risk analysis drives how risk assessments are used in practice. The current interpretation of uncertainty is that, in addition to the aleatory risk which arises from presumed uncertainty in the world, it comprises the epistemic aspects of irresolution in a model or forecast, specifically model and parameter uncertainty. This is true in part but it is not all there is to uncertainty in risk analysis. The physics of hazards and of failure may be poorly understood, which goes beyond uncertainty in its conventional sense. There may be alternative scenarios of future conditions, for example non-stationarity in the environment, which cannot easily be forecast. There may also be deep uncertainties of the type associated with climate change. These are situations in which analysts do not know or do not agree on the system characterisation relating actions to consequences or on the probability distributions for key parameters. All of these facets are part of the uncertainty in risk analysis with which we must deal. 相似文献
13.
《地学前缘(英文版)》2020,11(6):2297-2308
Quantification of a mineral prospectivity mapping (MPM) heavily relies on geological, geophysical and geochemical analysis, which combines various evidence layers into a single map. However, MPM is subject to considerable uncertainty due to lack of understanding of the metallogenesis and limited spatial data samples. In this paper, we provide a framework that addresses how uncertainty in the evidence layers can be quantified and how such uncertainty is propagated to the prediction of mineral potential. More specifically, we use Monte Carlo simulation to jointly quantify uncertainties on all uncertain evidence variables, categorized into geological, geochemical and geophysical. On stochastically simulated sets of the multiple input layers, logistic regression is employed to produce different quantifications of the mineral potential in terms of probability. Uncertainties we address lie in the downscaling of magnetic data to a scale that makes such data comparable with known mineral deposits. Additionally, we deal with the limited spatial sampling of geochemistry that leads to spatial uncertainty. Next, we deal with the conceptual geological uncertainty related to how the spatial extent of the influence of evidential geological features such as faults, granite intrusions and sedimentary formations. Finally, we provide a novel way to interpret the established uncertainty in a risk-return analysis to decide areas with high potential but at the same time low uncertainty on that potential. Our methods are illustrated and compared with traditional deterministic MPM on a real case study of prospecting skarn Fe deposition in southwestern Fujian, China. 相似文献
14.
We present a new approach for modelling annealing of fission tracks in apatite, aiming to address various problems with existing models. We cast the model in a fully Bayesian context, which allows us explicitly to deal with data and parameter uncertainties and correlations, and also to deal with the predictive uncertainties. We focus on a well-known annealing algorithm [Laslett, G.M., Green, P.F., Duddy, I.R., Gleadow. A.J.W., 1987. Thermal annealing of fission tracks in apatite. 2. A quantitative-analysis. Chem. Geol., 65 (1), 1-13], and build a hierachical Bayesian model to incorporate both laboratory and geological timescale data as direct constraints. Relative to the original model calibration, we find a better (in terms of likelihood) model conditioned just on the reported laboratory data. We then include the uncertainty on the temperatures recorded during the laboratory annealing experiments. We again find a better model, but the predictive uncertainty when extrapolated to geological timescales is increased due to the uncertainty on the laboratory temperatures. Finally, we explictly include a data set [Vrolijk, P., Donelick, R.A., Quenq, J., Cloos. M., 1992. Testing models of fission track annealing in apatite in a simple thermal setting: site 800, leg 129. In: Larson, R., Lancelet, Y. (Eds.), Proceedings of the Ocean Drilling Program, Scientific Results, vol. 129, pp. 169-176] which provides low-temperature geological timescale constraints for the model calibration. When combined with the laboratory data, we find a model which satisfies both the low-temperature and high-temperature geological timescale benchmarks, although the fit to the original laboratory data is degraded. However, when extrapolated to geological timescales, this combined model significantly reduces the well-known rapid recent cooling artifact found in many published thermal models for geological samples. 相似文献
15.
运用板块构造理论解释造山带地质演化是当前地质学研究的难点，也是地质学基础理论创新的可能方向。包括印度 欧亚大陆侧向碰撞带在内的国内、外造山带构造演化尚未取得共识，大多表现为“大量高质量数据与诸多充满争议的演化模型共存”。产生这些争议的主要原因包括“高质量数据”的时、空分布样式未受足够重视、以及部分关键地质体物理属性鉴别存在争议。这些问题为地质学发展与理论创新留下了巨大的空间。持续10多年西南三江造山带区域地质填图、构造解析揭示了侧向碰撞带构造格架、地壳变形历史，提出了印度 欧亚大陆碰撞新的三阶段模型。这一研究实践表明，严格按照 “构造解析方法”体现的“三步骤”研究范式开展区域地质填图是造山带理论创新的基础与保障。区域地质填图是造山带研究中难度最大的工作之一，要求填图人员必须具备广泛、坚实的地质学理论基础，以及运用基础理论解决实际问题的能力。 相似文献
16.
The new frontiers of the oil industry are deep offshore reservoirs, fields located in harsh environments with unconventional
hydrocarbon accumulations. Extraction of oil or gas from these environments share technical challenges and high development
costs. Consequently, an evaluation of the risks associated with exploiting these resources is needed before any investment
decisions are made. Potential risks can be properly assessed only by considering all the possible sources of uncertainty affecting
the reservoir characterization. Porosity, fluid saturations and net to gross are strategic information used to both calculate
hydrocarbon originally in place and define proper field development plans. These quantities are obtained through the log interpretation
process, which is an inverse problem where the main petrophysical characteristics are calculated as the acceptable minimum
of a cost function describing the discrepancy between measured and simulated logs, the latter being reproduced on the basis
of an assumed formation model. The results of the calculation process can be affected by several uncertainties related to
the physics and calibration of the measuring tools, the identification of the proper formation model, and the quantification
of the model coefficients. An effective methodology able to provide a reliable evaluation of the hydrocarbon volume and the
assessment of the associated uncertainties is presented and discussed in this paper. The log interpretation process was approached
as a linearly constrained optimization problem, solved by coupling a Lagrange-Newton method with a primal active set algorithm.
The evaluation of the uncertainties was obtained by coupling the optimization algorithm with the Monte Carlo approach. The
results obtained by the application of the methodology to a real case are shown. 相似文献
17.
Facies reconstructions are used in hydrogeology to improve the interpretation of aquifer permeability distribution. In the absence of sufficient data to define the heterogeneity due to geological processes, uncertainties in the distribution of aquifer hydrofacies and characteristics may appear. Geometric and geostatistical methods are used to understand and model aquifer hydrofacies distribution, providing models to improve comprehension and development of aquifers. However, these models require some input statistical parameters that can be difficult to infer from the study site. A three-dimensional reconstruction of a kilometer scale fine-grain dominated Cenozoic alluvial fan derived from more than 200 continuously cored, closely spaced, and regularly distributed wells is presented. The facies distributions were reconstructed using a genetic stratigraphic subdivision and a deterministic geostatistical algorithm. The reconstruction is only slightly affected by variations in the geostatistical input parameters because of the high-density data set. Analysis of the reconstruction allowed identification in the proximal to medial alluvial fan zones of several laterally extensive sand bodies with relatively higher permeability; these sand bodies were quantified in terms of volume, mean thickness, maximum area, and maximum equivalent diameter. These quantifications provide trends and geological scenarios for input statistical parameters to model aquifer systems in similar alluvial fan depositional settings. 相似文献
18.
Quasi-Stochastic Analysis of Uncertainty for Modelling Structurally Controlled Failures 总被引：1，自引：0，他引：1
In one approach to predicting the behaviour of rock masses, effort is being devoted to the use of probabilistic methods to model structures interior to a rock mass (sometimes referred to as ‘inferred’ or ‘stochastic’ structures). The physical properties of these structures (e.g. position, orientation, size) are modelled as random parameters, the statistical properties of which are derived from the measurements of a sample of the population (sometimes referred to as ‘deterministic’ structures). Relatively little attention has been devoted to the uncertainty associated with the deterministic structures. Typical geotechnical analyses rely on either an entirely stochastic analysis, or deterministic analyses representing the structures with a fixed shape (i.e. disc), position, size, and orientation. The simplifications assumed for this model introduce both epistemic and stochastic uncertainties. In this paper, it is shown that these uncertainties should be quantified and propagated to the predictions of behaviour derived from subsequent analyses. We demonstrate a methodology which we have termed quasi-stochastic analysis to perform this propagation. It is shown that relatively small levels of uncertainty can have large influence on the uncertainties associated with geotechnical analyses, such as predictions of block size and block stability, and therefore this methodology can provide the practitioner with a method for better interpretation of these results. 相似文献
19.
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
20.
Structural uncertainty exists when associating sparse fault interpretations made from two-dimensional seismic lines or limited outcrop observations. Here, a graph formalism is proposed that describes the problem of associating spatial fault evidence. A combinatorial analysis, relying on this formalism, shows that the number of association scenarios is given by the Bell number, and increases exponentially with the number of pieces of evidence. As a result, the complete exploration of uncertainties is computationally highly challenging. The available prior geological knowledge is expressed by numerical rules to reduce the number of scenarios, and the graph formalism makes structural interpretation easier to reproduce than manual interpretation. The Bron–Kerbosch algorithm, which finds maximal cliques in undirected graphs, is used to detect major possible structures. This framework opens the way to a numerically assisted exploration of uncertainties during structural interpretation.
相似文献