Spatial simulation of geologic variables

Analytical formulation of a general simulation model for generation of anisotropic as well as isotropic synthetic patterns in one, two, or three dimensions is proposed. It has significance for the purpose of modeling geologic properties such as ore grades, reservoir porosity, mineral distribution, fracture spacings, aperture, orientations, etc. General procedures for such a simulation by the autoregressive process are given for model parameters estimation and synthetic pattern generation. The model works on the square net basis and generates sequential patterns first along any desired direction for unidimensional simulation and then two-dimensional patterns are constructed with reference to two orthogonal unidimensional sequences. Applications to synthetic two-dimensional pattern are shown for isotropic cases with different model parameters. The extension of the model to three-dimensional space is readily available.     

浅谈地质灾害危险性评估工作中危害级别划分

阐述评估范围、地质环境条件复杂程度、地质灾害危险性在评估工作中的划分标准及其重要性。     

Z-trend maps for quick recognition of geologic patterns

Z-trend maps are a simplified lineprinter version of spatially filtered maps designed to give a quick visual appraisal of trends. The printout shows a yes-no configuration by a printed character or a blank so that the map has a conspicuous pattern. This pattern reflects the presence, position, and trend of the desired features. If a reasonable symbol density ratio is used the results can be visually pleasing thus enhancing trend recognition. Z-trending can be adapted to any map with stationary properties but is most easily applied to data that have been filtered with a bandpass operator.     

我国矿山环境地质问题类型划分研究

根据矿种类型、矿山开发阶段和矿山存在问题性质的不同,提出了我国矿山环境地质问题类型的3种划分方案。依据矿种所进行的矿山环境地质问题类型划分方案,虽然较为详细具体,但有些问题是相互重复的;依据矿山开发阶段所进行的划分方案,虽然刻画了矿山开发演变整个历史过程中所面临的不同问题,但较为宏观简单;依据矿山自身存在问题的性质的划分方案较为适用。文章最后系统分析了依据问题性质而划分的矿山环境地质问题各类型的特征。     

Scaling variables and interpretation of eigenvalues in principal component analysis of geologic data

The dominant feature distinguishing one method of principal components analysis from another is the manner in which the original data are transformed prior to the other computations. The only other distinguishing feature of any importance is whether the eigenvectors of the inner product-moment of the transformed data matrix are taken directly as the Q-mode scores or scaled by the square roots of their associated eigenvalues and called the R-mode loadings. If the eigenvectors are extracted from the product-moment correlation matrix, the variables, in effect, were transformed by column standardization (zero means and unit variances), and the sum of the p-largest eigenvalues divided by the sum of all the eigenvalues indicates the degree to which a model containing pcomponents will account for the total variance in the original data. However, if the data were transformed in any manner other than column standardization, the eigenvalues cannot be used in this manner, but can only be used to determine the degree to which the model will account for the transformed data. Regardless of the type of principal components analysis that is performed—even whether it is Ror Q-mode—the goodness-of-fit of the model to the original data is given better by the eigenvalues of the correlation matrix than by those of the matrix that was actually factored.     

Inundation patterns and plant growth in constructed wetland characterized by dynamic water budget model

Inundation patterns and plant establishment were observed in a riparian wetland mitigation project following predictions made by a dynamic water budget model. The model combined field measurements of hydrologic variables, historical weather observations, and digital elevation data in a geographic information system. It identified one excavation among four candidates as most likely to thrive in a harsh environment with periodic drought and extreme water level fluctuations. Observed, pulsing inundation patterns are consistent with predictions made by the model. Numerous native species, many found on site, were planted in the excavation; more than half of them survived a year-long period of observation with months of no standing water. The most successful species were graminoids (especially Cyperus acuminatus), a forb (Eclipta prostrata), and herbs (especially Hibiscus laevis and Polygonum densiflorum) capable of extracting soil moisture during prolonged dry spells.     

铂族元素矿床特征及成因分类探讨

在收集国内外铂族元素矿床地质特征的基础上,审视了国内外不同学者对铂族元素矿床的分类方案,综合矿床容矿岩石类型、共生元素组合、矿化类型和矿床类型并结合形成环境,对铂族元素矿床进行了系统的总结和分类,划分为四类十二亚类。同时重点论述了具有开发前景的典型铂族元素矿床的基本特征、成矿物质来源和形成环境及成矿的关键问题。     

西昌市地质灾害发育分布规律及防灾建议

西昌市地处川西的安宁河流域,区内地质条环境件复杂,生态环境脆弱,泥石流、滑坡等地质灾害发育,给当地居民生命财产安全及经济发展带来了较大影响。本文通过对西昌市目前发育的153处不同类型的地质灾害进行统计,总结了地质灾害在流域、高程、时段等方面的分布规律;对影响或控制西昌市地质灾害发育的地形地貌、构造、岩土体结构、地震、降雨及人类工程活动等因素进行了分析、总结;并针对西昌市的地质灾害类型及发育分布特征提出了适用于该地区的科学、合理的地质灾害防灾建议。     

大型地下洞室复杂地质断层数值模拟分析方法

根据大型地下洞室中复杂断层对围岩稳定的影响,提出了隐含断层单元的数值模拟计算方法。该方法将复杂断层单元隐含在岩体单元中,使得岩体单元的剖分不受断层切割的影响。使用这种隐含的断层单元,不但将受复杂断层切割的大型复杂地下洞室群的有限单元离散简单化,加快分析计算周期,而且能够有效地反映断层对复杂地下洞室围岩稳定的影响。通过对三峡地下厂房复杂断层结构的分析计算,证明该方法为复杂断层结构的分析提供了一种十分有效的计算方法和思路。     

地质封存二氧化碳沿断层泄漏数值模拟研究

安全性和封存效果是二氧化碳（CO2）地质封存（GCS）最受关注的问题,其中以断层/裂缝引起的场地不确定性因素较为复杂。利用储层多相流模拟软件TOUGH2/ECO2N,研究了不同情境下注入深部咸水层中的CO2沿断层发生泄漏的时间、速率、泄漏量等特征。通过15个场地尺度的模型结果分析表明,CO2注入方案、断层性质（发育位置、产状、几何形态、内部结构）、系统内岩层的组合形态对CO2泄漏均有影响。相同储存环境和断层发育条件下,CO2注入速率从1.59 kg/s增加至6.34 kg/s,CO2泄漏时间提前3 706 d,泄漏量在20 a后增加至注入总量的32.43%。断层发育位置对CO2封存影响极为显著,本次研究,距注入井100 m位置的断层可造成CO2的泄漏量在20 a后高达总注入量的63.39%。相同条件下,倾斜/窄小的断层比垂直/宽厚的断层对CO2及储层咸水的泄漏影响更小。断层渗透率增加一倍,可导致CO2泄漏量增加2.11%,泄漏速率约提高0.006~0.01 kg/s。     

Stratigraphic correlation of subsurface geologic data by computer

Manual, semiautomatic, and fully automatic procedures for correlating subsurface data are reviewed. Special emphasis is placed on the use of electric-log data, including that of the dipmeter log, in this discussion. The Holgate method is described for its use in fine-tuning or refining gross correlations. A procedure for creating a matrix map for empirically establishing correlation between sets of data is described, and idealized models are shown.This paper was presented at the 38th Session of the International Statistical Institute, Washington, D.C., 10–20 August 1971.     

CT扫描确定土壤大孔隙分布

对含有各种大孔隙的原状土柱和已知直径大孔隙的填充土柱进行CT扫描实验,阐明CT扫描原理和过程,对CT图像进行处理,得到大孔隙数目、大小、形状和连通性在土柱横断面和纵断面上的分布.采用图像处理软件Photoshop、地理信息系统软件ARC/INFO和Mapinfo分析结果表明:CT扫描是一种有发展前景的、非破坏性的确定土壤大孔隙分布的方法.     

Stochastic simulation of categorical variables using a classification algorithm and simulated annealing

An important step of reservoir characterization is the stochastic modeling of the geometry of lithofacies which control large-scale heterogeneities of petrophysical properties. Although multiple realizations are necessary to appreciate the uncertainty in the spatial distribution of facies, a common short cut consists of retaining the first realization drawn. This paper presents an alternative to this potentially hazardous selection: (1) a categorical map is generated by allocating a single facies to each grid node according to the local probabilities of occurrence of the facies, and (2) the map then is post-processed using a steepest descent-type algorithm so as to improve reproduction of spatial continuity and transition probabilities between facies. The procedure is illustrated using a synthetic dataset. A waterflood simulation shows that retaining a single realization would yield, in average, larger errors in production forecasts (water cuts and recovered oil) than the single postprocessed facies map.