The characteristics and sources of natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin   总被引：2，自引：2，他引：0  

Xianqing Li  Guoyi Hu  Jian Li  Dujie Hou  Peng Dong  Zhihong Song  Yunfeng Yang 《中国地球化学学报》2008,27(2):109-120

The Central Gas Field is a famous large-sized gas field in the Ordos Basin of China. However, identification of main gas sources of the Ordovician reservoirs in this gas field remains puzzling. On the basis of a lot of geochemical data and geological research on natural gases, the characteristics and sources of natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin were studied. The results indicated that natural gases from Ordovician weathered crust reservoirs in the Central Gas Field in the Ordos Basin have similar chemical and isotopic compositions to highly mature and over-mature dry gases. Both coal-derived gases and oil-type gases coexist in the Central Gas Field in the Ordos Basin. The former was derived mainly from Carboniferous-Permian coal measures and the latter from Lower Paleozoic marine carbonates. It is suggested that coal-derived gases occur in the eastern part of the Central Gas Field while oil-type gases may be produced mainly in the northern, western and southern parts of the Central Gas Field in the Ordos Basin.  相似文献   

Rare-earth elements as source indicators of Pan-African granites from Obudu Plateau,Southeastern Nigeria   总被引：1，自引：1，他引：0  

V. U. Ukaegbu  F. T. Beka 《中国地球化学学报》2008,27(2):130-134

The rare-earth element （REE） concentrations of representative granite samples from the southeast of the Obudu Plateau, Nigeria, were analyzed with an attempt to determine the signatures of their source, evolutionary history and tectonic setting. Results indicated that the granites have high absolute REE concentrations （190×10^-6-1191×10^-6; av.=549×10^-6） with the chondrite-normalized REE patterns characterized by steep negative slopes and prominent to slight or no negative Eu anomalies. All the samples are also characterized by high and variable concentrations of the LREE （151×10^-6-1169×10^-6; av.= 466×10^-6）, while the HREE show low abundance （4×10^-6-107×10^-6; av.=28×10^-6）. These are consistent with the variable levels of REE fractionation, and differentiation of the granites. This is further supported by the range of REE contents, the chondrite-normalized patterns and the ratios of LaN/YbN （2.30-343.37）, CeN/YbN （5.94-716.87）, LaN/SmN （3.14-11.68） and TbN/YbN （0.58-1.65）. The general parallelism of the REE patterns, suggest that all the granites were comagmatic in origin, while the high Eu/Eu＊ ratios （0.085-2.807; av.=0.9398） indicate high fo2 at the source. Similarly, irregular variations in LaN/YbN, CeN/YbN and Eu/Eu＊ ratios and REE abundances among the samples suggest behaviors that are related to mantle and crustal sources.  相似文献   

Formation Dynamics and Quantitative Prediction of Hydrocarbons of the Superpressure System in the Dongying Sag   总被引：1，自引：0，他引：1  

SUI Fenggui  HAO Xuefeng  LIU Qing  ZHUO Qin’gong  ZHANG Shouchun 《《地质学报》英文版》2008,82(1):164-173

Based on the theory of formation dynamics of oil/gas pools, the Dongying sag can be divided into three dynamic systems regarding the accumulation of oil and gas： the superpressure closed system, the semi-closed system and the normal pressure open system. Based on the analysis of genesis of superpressure in the superpressure closed system and the rule of hydrocarbon expulsion, it is found that hydrocarbon generation is related to superpressure, which is the main driving factor of hydrocarbon migration. Micro fractures formed by superpressure are the main channels for hydrocarbon migration. There are three dynamic patterns for hydrocarbon expulsion： free water drainage, hydrocarbon accumulation and drainage through micro fissures. In the superpressure closed system, the oil-driving-water process and oil/gas accumulation were completed in lithologic traps by way of such two dynamic patterns as episodic evolution of superpressure systems and episodic pressure release of faults. The oil-bearing capacity of lithologic traps is intimately related to reservoir-forming dynamic force. Quantitative evaluation of dynamic conditions for pool formation can effectively predict the oil-bearing capability of traps.  相似文献   

地下水流模型识别的分步解法     

王晓明  王秀辉  郑重 《煤田地质与勘探》2008,36(5)

地下水流模型识别问题是综合的水文地质分析与计算过程,但常常被片面理解为反求水文地质参数问题,这种片面的认识大大妨碍了对水文地质条件的认识及对水文地质过程的理解,并由此导致一些不应有的错误结论。简要论述了地下水流模型识别的概念及问题类型,利用模型分解的方法指出地下水流模型的识别可分2步完成:一是利用附加水头场(或附加降深场)求参数;二是利用初始水头场确定边界条件及源汇项。除参数外,源汇项、初始条件、边界条件也是地下水流模型识别的重要内容。  相似文献   

三峡水库建设前后10年库区景观空间格局动态变化研究——以重庆开县为例   总被引：2，自引：1，他引：1  

邵怀勇  仙巍  杨武年  周万村 《测绘科学》2008,33(6):176-178

在遥感和地理信息系统技术的支持下,以1992年和2002年TM图像为基础,采用斑块密度、斑块平均面积、景观形状指数、景观分离度指数、景观多样性指数、景观优势度指数、景观相对聚集度指数深入而全面地研究了三峡工程建设前后十年重庆开县景观空间格局的动态变化,本研究的开展旨在为库区生态环境保护提供科学依据。研究结果表明,十年间研究区景观空间格局发生了明显变化,草地、未利用地、旱地、果园和水田面积净减,森林、建设用地、灌木林和水域面积增加,退耕还林已初见成效。  相似文献   

Open source, spatial analysis, and activity-travel behaviour research: capabilities of the aspace package   总被引：2，自引：0，他引：2  

Ron N. Buliung  Tarmo K. Remmel 《Journal of Geographical Systems》2008,10(2):191-216

This paper reports on recent experience with the development of aspace, an Open Source (OS) library for the geographic visualization and analysis of activity-travel behaviour. The paper begins with an overview of recent progress with respect to the convergence of Open Source technology, spatial analysis, and travel behaviour research. The remainder of the paper focuses on aspace; a collection of functions that, when combined with data describing the geographical location of daily activities, can be used to visualize and describe spatial properties of individual and household activity spaces. These properties include: size, orientation, shape, and the geographical dispersion of activity locations contained within the activity space. Several planar geometries are used to transform measurable spatial properties into intuitive objects for visualizing spatial patterns of activity participation. Experiments are conducted, using data from the first wave of the 2003 Toronto Travel Activity Panel Survey, to demonstrate the potential application of aspace for basic and applied policy-based research into activity-travel behaviour. The toolkit is distributed as a downloadable ‘package’ from the Open Source R Project for Statistical Computing.   相似文献   

长江流域沿江镉异常源追踪与定量评估的方法技术研究:以长江流域安徽段为例   总被引：5，自引：1，他引：4  

赵传冬  陈富荣  陈兴仁  赵和苍  夏威岚  聂海峰  孔牧  刘飞  杨柯 《地学前缘》2008,15(5):179

长江全流域性的Cd异常是被中国正在进行的多目标地球化学调查发现的重大生态环境问题。以长江流域安徽段为研究对象,对沿江镉异常源追踪与定量评估的方法技术进行了系统研究。通过对安徽段长江干流及其主要支流悬浮物中元素含量的测量查明:悬浮物是流域内重金属元素大跨度迁移的主要载体;Cd在悬浮物中的富集程度远远大于其他重金属元素,这或许正是Cd可以形成沿江流域性异常的主要原因;长江干流悬浮物中重金属元素含量的变化明显受到沿江支流的影响。安徽段长江干流及其主要支流重金属元素输出通量定量计算结果表明:秋蒲河是安徽段重金属元素输出通量最大的支流,每年在安徽段长江两岸土壤中沉积下约4.45t的Cd。利用悬浮物加密测量、1∶5万土壤测量和岩石测量对顺安河流域Cd异常源追踪结果显示:内生金属矿床特别是铅锌矿是悬浮物中Cd的最大的供应源。采用河漫滩沉积物分层采样技术和同位素测年技术,初步恢复了研究区Cd等重金属元素沉积和污染的地球化学历史,对研究区Cd等重金属元素异常的未来演变趋势进行了预警预测。  相似文献   

UKF算法及其在GPS卫星轨道短期预报中的应用     

郑作亚  陈永奇  卢秀山 《武汉大学学报(信息科学版)》2008,33(3):249-252

分析了GPS卫星预报星历,在比较分析EKF和UKF优缺点的基础上,将UKF引入GPS卫星轨道预报研究中.数值模拟和结果分析表明,UKF方法预报更稳定,能有效地提高轨道预报精度和稳定性.  相似文献   

青藏高原北部新生代陆相盆地石油地质条件及勘探前景          下载免费PDF全文

孙瑕  伊海生  林金辉  周恳恳  李军鹏  黄华谷 《沉积与特提斯地质》2008,28(4):7-13

青藏高原北部陆相盆地中烃源岩发育层位包括始新统风火山组、渐新统雅西措组和中新统五道梁组。古近系雅西措组烃源岩,特别是灰岩属于中好烃源岩范畴,有机质类型较好,且烃源岩主体处于成熟阶段,是藏北高原新生代陆相盆地主力烃源岩的发育层位。陆相盆地储集岩较发育,储层较丰富,发育层位包括风火山组和雅西措组,其中雅西措组是储层主力分布层位。对测区分析数据表明：通天河盆地具备一定规模的生油岩厚度,而且有机质丰度为沱沱河地区最高,表明其勘探前景较好。  相似文献   

大民屯凹陷烃源岩有机质丰度的恢复   总被引：2，自引：0，他引：2       下载免费PDF全文

逯向阳 《沉积与特提斯地质》2008,28(4):14-17

烃源岩有机质丰度的恢复具有重要的现实和理论意义。笔者在对比多种方法的基础上,对大民屯凹陷的烃源岩的有机质丰度进行了恢复。  相似文献