Scanline Method to Determine the Fractal Nature of 2-D Fracture Networks

A previous method proposed to measure the fractal dimension of pore spaces is adapted and modified for 2-D fracture networks. The method relies on scanning a 2-D fracture network through successive straight lines from top to bottom and measuring the distance between two fractures. The fractal dimension is then obtained using the log–log plot of the feature size and the number of features for this particular size at different magnifications. It is shown in this study that the method proposed to measure the fractal dimension of porous structures can be applicable to 2-D fracture networks with some modifications after testing it on synthetic and natural fracture patterns. The method is simplified to be useful for practical applications in the fractal analysis of fracture networks. The results reveal that, on the basis of the direction of scanning lines, different fractal behavior and dimensions can be obtained indicating that 2-D fracture networks possess multifractal character. This approach takes into account the effect of fracture orientation on the fractal behavior and anisotropic nature of fracture networks as well as the fracture density, length, and spatial distribution.     

Characterization and reconstruction of a rock fracture surface by geostatistics

It is well understood that, in studying the mechanical and hydromechanical behaviour of rock joints, their morphology must be taken into account. A geostatistical approach has been developed for characterizing the morphology of fracture surfaces at a decimetre scale. This allows the analysis of the spatial variability of elevations, and their first and second derivatives, with the intention of producing a model that gives a numerical three‐dimensional (3D) representation of the lower and upper surfaces of the fracture. Two samples (I and II) located close together were cored across a natural fracture. The experimental data are the elevations recorded along profiles (using recording steps of 0.5 and 0.02 mm, respectively, for the samples I and II). The goal of this study is to model the surface topography of sample I, so getting estimates for elevations at each node of a square grid whose mesh size will be, for mechanical purposes, no larger than the recording step. Since the fracture surface within the sample core is not strictly horizontal, geostatistical methods are applied to residuals of elevations of sample I. Further, since structural information is necessary at very low scale, theoretical models of variograms of elevations, first and second derivatives are fitted using data of both that sample I and sample II. The geostatistical reconstructions are computed using kriging and conditional simulation methods. In order to validate these reconstructions, variograms and distributions of experimental data are compared with variograms and distributions of the fitted data. Copyright © 2002 John Wiley & Sons, Ltd.     

陕西宽坪岩群变基性熔岩锆石U-Pb年龄

宽坪岩群广东坪岩组绿片岩岩石学、岩石化学、稀土、微量元素、副矿物等研究表明其原岩为基性火山岩。对商州市板桥地区基性熔岩变质而成的绿片岩区域地质、地球化学特点、锆石特征进行了详细研究和单颗粒锆石U-Pb同位素年龄测定。放射性成因铅丢失最少的岩浆成因锆石的206Pb/238U表面年龄为1154Ma,变质成因锆石的206Pb/238U表面年龄为444Ma。5个锆石颗粒构成的不一致线上交点年龄为1827±11Ma,代表基性熔岩形成年龄;下交点年龄为418±8Ma,代表加里东期变质年龄。综合认为宽坪岩群形成时代为早元古代。     

运用卫星像片研究中国大地构造

运用中国的卫星像片 ,发现中国大陆存在一个纵贯全国的“×”型剪切断裂系统。在此基础上进行了中国的断块划分及大地构造分区 ,并对中国大地构造结构上的特征和空间及时间上表现出的地壳波状运动进行了探讨。     

中国东部深层油藏隔层裂缝及其地质意义

中国东部深层油藏隔层由于其破裂压力小，受地静压力、构造应力的作用而形成裂缝，降低了其封闭性，从而影响油田注水开发的效果。以冀东油田高尚堡Es3^2 3油藏为例，综合地质、地震、测井和生产动态资料，应用一系列先进技术，对我国东部深层油藏隔层裂缝的基本特征、分布规律进行了深入的研究，分析了隔层裂缝的形成原因及其对注水开发的影响，并提出了解决措施。     

轮南地区奥陶系天然裂缝形成的控制因素与发育机理

地下天然裂缝是导致地质灾害的主要原因之一，轮南奥陶系埋深在5000m以下，岩体的天然裂缝不能直接观察，且其天然裂缝发育受多种因素控制，在地质演化过程中经多斯发育而成，发育机理非常典型、复杂。通过观察、描述岩芯的裂缝发育特征，分析深度、温度、围压、剥蚀、裂缝充填等因素对地下岩体力学性质的影响，确定了裂缝发育的控制因素。进而预测了裂缝发育概率分布和发育特点，分析了轮南地区奥陶系天然裂缝的发育机理。     

单裂隙面渗流特性及等效水力隙宽

首先讨论了描述单裂隙面几何特性的两个最基本参数——隙宽和粗糙性的确定方法,系统地总结和分析了现有有关单裂隙面渗流特性方面的研究成果,并对不同粗糙性描述下的裂隙等效水力隙宽的确定问题进行了探讨,提出了自已的看法,并指出进一步要解决的问题。     

水布垭水电站坝基岩体地质模型研究

围绕水布垭水电站坝基地质模型研究 ,开展了工程地质调查、岩石力学室内外测试和试验和工程应用的研究。在大量野外工作及理论分析的基础上 ,详细研究了水布垭水电站工程地质岩组 ,地质构造规律及坝基岩体地应力和水文地质条件 ,建立了坝基岩体的概化地质结构模型。开展了针对坝基基本地质模型单元的岩体质量评价 ,提出了坝基基本地质模型单元的岩体力学参数     

构造型水库地震的断裂力学分析

常见的水库地震有三种：断层破裂型（构造型）、浅表应力局部调整型（微破裂型）和岩溶型，构造型水库地震震级较高。本从地应力、库水压力、断层渗透水压力的分布规律着手，应用弹性断裂力学原理分析了三种应力产生的应力强度因子及总的应力强度因子，并从复合型应力强度因子的断裂判据，分析了水库地震的发震规律。     

平面可视化技术对山东德南断裂系的精细识别

德南断裂带是山东德南洼陷的主要油气聚集场所 ,精细识别各断层的分布有重要的现实意义。将平面可视化技术应用于德南断裂的精细识别取得了很好的效果 ,已识别出德南断裂是一个向西散开的断裂系 ,它从北到南由 1、 2、 3号北倾断层组成 ;1、 2号断层最终汇聚为一条 ,2号断层下降盘发育 3～ 4条反向补偿断层 ;3号断层是一个小型的断裂系 ,由 5～ 7个北倾断层组成 ,平面上亦向西散开 ;剖面上该断裂系主要反映为向上分开、向下汇聚的帚状断裂系 ;同时还发现了由 3号断裂系控制的断块群。对德南断裂系的精细识别为进一步的钻井勘探和储层建模的研究提供了可靠的依据