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951.
952.
Genetic Relationship between Natural Gas Dispersal Zone and Uranium Accumulation in the Northern Ordos Basin, China
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The Ordos Basin is well-known for the coexistence of oil, natural gas, coal and uranium. However, there has been little research to discuss the genetic relationship between them. In this paper, a case study of the Zaohuohao area in Dongsheng, Inner Mongolia, China, is conducted to investigate the genetic relationship between the natural gas and the uranium accumulation. Fluid inclusion data from the uranium-bearing sandstone samples indicate that the fluid inclusions formed in a gas-water transition zone. Using the homogeneous temperatures of aqueous inclusions coeval with hydrocarbon-bearing inclusions, combined with the buried history and paleo-temperature data, the gas-water transition zone reached the area at about 110 Ma. On the basis of this, the contents of Uranium (U) and Total Organic Carbon (TOC) of the samples were analyzed, and there was no obvious relation between them. With regard to the available data from both publications and this study, it is found that the U mineralization has a spatiotemporal accordance with the gas-water dispersal zone. Thus, it is believed that the natural gas in the gas-water zone is an effective reducer to the U-bearing ground water abundant in oxygen, which is the main factor to U accumulation. This result can be used as the reference to the U mines predicting and prospecting. 相似文献
953.
954.
MHz-to-kHz electromagnetic (EM) anomalies have been detected worldwide over time intervals ranging from a few days to a few hours prior to near-surface earthquakes (EQs) that have occurred on land with magnitude approximately six or larger. The MHz radiation systematically appears earlier than the kHz. Laboratory experiments on rock samples reveal a similar change in the frequency content during progressive deformation, i.e. the emissions exhibit a frequency shift from MHz to kHz just before failure of the samples. Herein, we attempt to associate these consecutively emerging MHz and kHz modes of the pre-fracture EM emission with successive distinct stages of the fracture preparation process and the associated fracture mechanisms. We base our approach on synergetic principles of physical mesomechanics. A universal principle of physical mesomechanics is that the plastic deformation of a solid is related to its loss of shear stability at the micro-, meso-, and macroscale levels. Global fracture is determined by the mechanism controlling the development of macroscale bands of localized deformation associated with meso- and microscale relaxation processes. The major result we obtain is that the shift from MHz to kHz EM activity may signal the transition of plastic flow localization from the mesoscale to the macroscale, culminating in global fracture. A complexity measure (Approximate Entropy) and a persistency–anti-persistency measure (Hurst exponent) also give evidence of a two stage-model of EQ preparation process: significant complexity decrease and accession of persistency can be confirmed in the strong kHz EM activity that emerges in the tail of the pre-seismic EM activity. Laboratory experiments on rock samples reveal similar symptoms of an imminent global instability. 相似文献
955.
由于自然伽马能谱测井(NGS)的放射性元素U、Th、K的含量与粘土矿物有着密切的关系,所以可利用NGS定性或定量确定油气储层粘土矿物含量。阐述了自然伽马能谱测井资料在确定粘土矿物含量中的地质依据,建立了研究地层粘土矿物含量的计算模型。由研究油田的NGS测井资料计算并对比了粘土矿物的含量,最终得到很好的效果。 相似文献
956.
本研究建立了一个反映植被辐射传输和几何光学特性的混合模型,以模拟半干旱地区天然草地的多波段反射率值。该模型引入一个几何相似性参数,用以描述植株冠层的几何形状对叶/枝角分布、阴影地面比例、冠层和地面各光学分量、冠层反射率和总反射率的影响。模型模拟值与研究区3个不同退化程度羊草草地的实测值较为吻合,而且退化程度越轻的草地,模拟效果也越好。对于中度退化草地,在高度与冠幅之比(chw)不变的情况下,当45°≤太阳天顶角sza≤75°时,不同几何形状植株的总反射率之间无显著差异;当0°≤sza〈45°或75°〈sza≤90°时,锥体与球体和柱体植株的总反射率之间有较显著差异;而球体和柱体植株的总反射率之间始终无显著差异。当chw由小到大变化时,以上结论基本不变。 相似文献
957.
利用全方位P波属性进行裂缝检测的地震方法 总被引:2,自引:0,他引:2
胜利油田存在着一种特殊的裂隙性油气藏,即泥岩裂隙油气藏。由于该类裂隙储层的孔隙度很小,岩石物性参数变化不灵敏,并表现出很强的各向异性,因此,其勘探难度很大。到目前为止,国内外还没有一套成熟的地质、物探、测井及钻井等资料综合分析的裂隙方位、分布、密度的识别方法。本文在研究国外裂缝检测方法的基础上,提出了波阻抗随方位变化(IPVA)的新方法,结合罗家地区的泥岩裂隙地震地质特征,研究了利用多方位 P 波资料检测定向垂直裂缝的地震采集、处理和识别方法,对不同共中心点 CMP 位置的全方位 P 波资料在速度随方位变化(VVA)及振幅随方位角变化(RVA)研究的基础上,进行波阻抗随方位变化(IPVA)的研究,用于识别裂缝的分布、走向及密度。经罗家地区实际资料的应用,见到了初步的效果,证明该方法是潜力较大的高角度裂隙的定量检测方法。 相似文献
958.
Antonino D’Andrea Salvatore Cafiso Antonio Condorelli 《Pure and Applied Geophysics》2005,162(4):767-782
The recent earthquakes in California and Japan have shown the fundamental role that the road infrastructure plays in emergencies. In fact, only the maintenance of a sufficient level of efficiency can help to quickly reach the affected areas and thus avoid further serious consequences. The necessity of guaranteeing the functionality of the transport network during seismic events therefore requires seismic risk planning extended also to the road infrastructures in order to support the management of post-earthquake emergencies. Analogously it is fundamentally important to have analysis instruments of the road system able to preventatively evaluate the effects of earthquakes in order to identify possible emergencies, therefore preparing a program of intervention to reduce seismic risk on road networks. This paper proposes a methodology for the evaluation of seismic risk of road infrastructures according to the following points:Study of seismic hazard of the site for the definition of a seismic scenario using attenuation models in relation to historical seismology and the geological and tectonic characteristics of the territory;Analysis of the direct exposure connected to the probability of the presence of road users on the different parts of the network directly exposed to the seismic event;Analysis of the indirect exposure relative to the distribution of the population and the infrastructures for which post-earthquake accessibility must be guaranteed;Evaluation of the functional vulnerability in relation to the potential replaceability of damaged stretches considering network configuration and geometrical characteristics;Evaluation of structural vulnerability of the stretch correlated to the characteristics (structural, mechanical, technological, etc.) of the different components (bridges, embankments, trenches, tunnels) that make up the stretches obtained by the use of correctly elaborated tables for each component.The determination of global risk indexes of the single stretches and of the network, evaluated by means of a relationship between the ascertained parameters derived from the investigation of the previous points, provides the necessary information for the definition of mitigation measures to reduce the risk and for management planning before and after disaster. The proposed methodology, which has already been applied to a restricted area, is currently being applied to the province of Catania (Sicily, Italy), which is one of the geographical regions of highest seismic risk in Europe, and its future extension to all of eastern Sicily is foreseeable. 相似文献
959.
漠滨金矿的可见金中,有一种呈聚集式乳滴状结构的自然金集合体。本文就其形成机理进行了探讨。这种结构显示的自然金的运动趋势和历史,为原生粗粒金的形成提供了一种可以探讨的途径。 相似文献
960.
Ethanol Production Using Corn,Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower 总被引:23,自引:0,他引:23
Energy outputs from ethanol produced using corn, switchgrass, and wood biomass were each less than the respective fossil energy inputs. The same was true for producing biodiesel using soybeans and sunflower, however, the energy cost for producing soybean biodiesel was only slightly negative compared with ethanol production. Findings in terms of energy outputs compared with the energy inputs were: • Ethanol production using corn grain required 29% more fossil energy than the ethanol fuel produced. • Ethanol production using switchgrass required 50% more fossil energy than the ethanol fuel produced. • Ethanol production using wood biomass required 57% more fossil energy than the ethanol fuel produced. • Biodiesel production using soybean required 27% more fossil energy than the biodiesel fuel produced (Note, the energy yield from soy oil per hectare is far lower than the ethanol yield from corn). • Biodiesel production using sunflower required 118% more fossil energy than the biodiesel fuel produced. 相似文献