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151.
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153.
Genetic Analogy Between Sediment—Hosted Gold Deposits and Sediment—Hosted Copper Deposits in Southwest China 总被引:1,自引:0,他引:1
The sediment-hosted copper deposits according to the authors‘ study were formed from connate formation water during the post-sedimentary or diagenetic stage while the sediment-hosted disseminated gold deposits are unanimously considered to be of post-sedimentary hydrothermal origin.Therefore,apart from their own individulities.These two types of deposits must share some characters in common.Comparisons are attempted,in this paper,between the sediment-hosted copper deposits in southwest China and the Triassic sediment-hosted disseminated gold deposits in the Yunnan-Guizhou-Guangxi Triangle in terms of geological and geochemical features. 相似文献
154.
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156.
Simulation of multigaussian stochastic fields can be made after a Karhunen-Loéve expansion of a given covariance function.
This method is also called simulation by Empirical Orthogonal Functions. The simulations are made by drawing stochastic coefficients
from a random generator. These numbers are multiplied with eigenfunctions and eigenvalues derived from the predefined covariance
model. The number of eigenfunctions necessary to reproduce the stochastic process within a predefined variance error, turns
out to be a cardinal question. Some ordinary analytical covariance functions are used to evaluate how quickly the series of
eigenfunctions can be truncated. This analysis demonstrates extremely quick convergence to 99.5% of total variance for the
2nd order exponential (‘gaussian’) covariance function, while the opposite is true for the 1st order exponential covariance
function. Due to these convergence characteristics, the Karhunen-Loéve method is most suitable for simulating smooth fields
with ‘gaussian’ shaped covariance functions. Practical applications of Karhunen-Loéve simulations can be improved by spatial
interpolation of the eigenfunctions. In this paper, we suggest interpolation by kriging and limits for reproduction of the
predefined covariance functions are evaluated. 相似文献
157.
鄂尔多斯盆地奥陶系海相碳酸盐岩生烃性能与中部长庆气田气源成因研究 总被引:15,自引:0,他引:15
用激光 -荧光显微镜等有机岩石学方法 ,挑选样品中有明显生、排烃现象的碳酸盐岩 ,再以测定的这类碳酸盐岩的有机碳含量为依据 ,确定本区高成熟碳酸盐气源岩残余有机碳的下限指标用 0 .13%~ 0 .14 %比较合理。根据碳酸盐岩储层孔隙中充填沥青和皮膜状残余沥青的分布和含量 ,论证了陕参 1井等奥陶系碳酸盐岩地层在地质历史中 ,存在若干油气有效储层。采用连续升温 ,步进取样的热模拟实验方法 ,揭示了本区煤与碳酸盐岩干酪根随热演化作用增强 ,烃类气体产物的干燥系数增大 ,δ1 3C1 、δ1 3C2 明显变重的规律 ,并根据样品实验结果推算 ,本区石炭系—二叠系煤最大生气阶段的δ1 3C1 应为 - 2 7‰~ - 2 8‰ ,碳酸盐岩最大生气阶段的δ1 3C1 应为- 31.7‰~ - 33‰。在气源成因判识中 ,根据主生气期阶段对天然气成藏储聚的贡献最大、甲烷碳同位素较重以及长庆气田风化壳气藏天然气δ1 3C1 重值区并不与石炭系—二叠系煤的镜质组反射率高值区匹配的现象等进行气源判识 ,认为长庆奥陶系风化壳气藏 ,具有下古生界海相碳酸盐岩气与上古生界石炭系—二叠系煤成气的混源成因 相似文献
158.
159.
We study the importance of the zones of weakness and the pattern of downgoing flow in steady-state models of subducting lithosphere, which interacts mechanically and thermally with the ambient mantle. The non-linear system of governing equations consists of (i) the momentum equation in stream function formulation and (ii) the steady-state heat transfer equation including conduction and advection of heat and dissipation. A finite element method has been applied to this system. We consider the viscosity to be a non-linear function of both the temperature and the stream function. In steady-state two-dimensional (2D) flow, the stream function isolines follow material trajectories. They are used to follow the top of the subducting slab, which because of its possible increase in water content, is assumed to have a lower viscosity. The zone of weakness has been thus obtained in the self-consistent fashion since the stream function as well as the temperature are the output from our modeling and no a priori assumptions about the shape of the bending lithosphere are taken into account. It was shown that several orders decrease of viscosity in the zone of weakness is required to obtain the dip angle of about 45°. If the decrease of viscosity is not sufficient enough, the subducted slab either sinks almost vertically or does not exhibit a plate-like behavior. We have also demonstrated that shear heating can unrealistically increase at the zone of weakness for fast subductions if decrease of viscosity is underestimated. 相似文献
160.
MI Jingkui XIAO Xianming LIU Dehan & SHEN Jiagui .State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China .Institute of Sedimentary Mineral Resources Department of Civil Engineering Xiangtan Polytechnic University Xiangtan China 《中国科学D辑(英文版)》2004,(6)
~~Determination of paleo-pressure for a natural gas pool formation based on PVT characteristics of fluid inclusions in reservoir rocks——A case study of Upper-Paleozoic deep basin gas trap of the Ordos Basin~~ 相似文献