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Effects of salinity on methane gas hydrate system

Science china earth {2. 2007年第11期50卷 1733-1745页

作者： YANG DingHui1 & XU WenYue2.1 Department of Mathematical sciences, Tsinghua university, {2. 100084, china 2.school of earth & Atmospheric sciences, Georgia Institute of Technology, Atlanta, GA 30332. USA Department of Mathematical sciences Tsinghua University Beijing China school of earth & Atmospheric {2. Georgia Institute of Technology Atlanta USA

Using an approximately analytical formation, we extend the steady state model of the pure methane hydrate system to include the salinity based on the dynamic model of the methane hydrate system. The top and bottom boundaries of the methane hydrate stability zone (MHSZ) and the actual methane hy-drate zone (MHZ), and the top of free gas occurrence are determined by using numerical methods and the new steady state model developed in this paper. Numerical results show that the MHZ thickness becomes thinner with increasing the salinity, and the stability is lowered and the base of the MHSZ is shifted toward the seafloor in the presence of salts. As a result, the thickness of actual hydrate occur-rence becomes thinner compared with that of the pure water case. On the other hand, since lower solubility reduces the amount of gas needed to form methane hydrate, the existence of salts in sea-water can actually promote methane gas hydrate formation in the hydrate stability zone. Numerical modeling also demonstrates that for the salt-water case the presence of methane within the field of methane hydrate stability is not sufficient to ensure the occurrence of gas hydrate, which can only form when the methane concentration dissolved in solution with salts exceeds the local methane solubility in salt water and if the methane flux exceeds a critical value corresponding to the rate of diffusive methane transport. In order to maintain gas hydrate or to form methane gas hydrate in marine sedi-ments, a persistent supplied methane probably from biogenic or thermogenic processes, is required to overcome losses due to diffusion and advection.

关键词： methane gas hydrate,solubility,stability of hydrate,salinity,phase equilibrium

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Thermodynamic conditions of framework grain dissolution of clastic rocks and its application in Kela 2.gas field

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Science china earth {2. 2005年第1期48卷 21-31页

作者： LAI Xingyun, YU Bingsong, CHEN Junyuan, CHEN Xiaolin, LIU Jianqing, MEI Mingxiang, JING Weiguang & CHENG Suhua school of earth {2. and mineral resources, china university of Geo{2., beijing 100083, china Key Laboratory of Lithospheric Tectonics, Deep-level Process and Exploration of Ministry of Education, beijing 100083, china china university of Geo{2. School of Earth Sciences and Mineral Resources Beijing China Key Laboratory of Lithospheric Tectonics Deep-level Process and Exploration of Ministry of Education Beijing China

Feldspar and clastic debris are the most important constituent framework grains of sedimentary clastic rocks and their chemical dissolution plays an essential role in the formation and evolution of the secondary pore in the reservoir rocks. On the basis of thermodynamic phase equilibrium, this study investigates the chemical equilibrium relationships between fluid and various plagioclase and K-feldspar in diagenesis of the sediments, particularly, the impact of temperature and fluid compositions (pH, activity of K+, Na+, Ca2. and so on) on precipitation and dissolution equilibria of feldspars. Feldspar is extremely easily dissolved in the acid pore water with a low salinity when temperature decreases. The dissolution of anorthite end-member of plagioclase is related to the Ca content of the mineral and the fluid, higher Ca either in the mineral or in the fluid, easier dissolution of the feldspar. Moreover, the dissolution of albite end-member of plagioclase is related to Na of both the mineral and fluid, lower Na out of both the mineral and fluid, easier dissolution of the mineral. Similarly, lower-K fluid is more powerful to dissolve K-feldspar than the higher. The anorthite component of plagioclase is most easily dissolved in ground water-rock system, the albite is the secondary, and K-feldspar is the most stable. Selective dissolution of plagioclase occurs in diagenesis because of the plagioclase solid solution that is mainly composed of albite and anorthite end-members, Ca-rich part of which is preferentially dissolved by the pore water, in contrast to the Na-rich parts. Based on investigation of reservoir quality, secondary pore, dissolution structures of feldspar, clay minerals and ground water chemistry of the Kela 2.gas field of Kuqa Depression in the Tarim basin of Western china, we discovered that the secondary pore is very well developed in the highest quality section of the reservoir, and the plagioclase of which was obviously selectively dissolved, in c

关键词： dissolution of feldspar, thermodynamic conditions, groundwater pore chemistry, Kela 2 gas field.

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Response of remotely sensed Normalized Difference Water Deviation Index to the 2.06 Drought of eastern Sichuan Basin

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Science china earth {2. 2008年第5期51卷 748-758页

作者： ZHANG WenJiang1, LU QiFeng2. GAO ZhiQiang3 & PENG Jian4 1 school of Water Resource and Hydropower, Sichuan university, Chengdu 610065,{2. 2.National Satellite Meteorological Center,{2. Meteorological Administration, beijing 100081,{2. 3 Institute of Geographic sciences and Natural resources Research, Chinese Academy of sciences, beijing 100101,{2. 4 school of Environmental sciences, Peking university, beijing 100871,{2. school of Water Resource and Hydropower Sichuan University Chengdu China National Statellite Meteorological Center China Meteorological Administration Beijing China Institute of Geographic sciences and Natural resources Research Chinese Academy of Sciences Beijing China school of Environmental sciences Peking University Beijing China

One of the most serious droughts in last century occurred in eastern Sichuan Basin in the summer of 2.06 (hereinafter called the Drought). The response of Moderate Resolution Imaging Spectroradiometer (MODIS, boarding on NASA satellites of Terra and Aqua) to the Drought was analyzed in order to reach one practicable monitoring solution for regional soil moisture. Temporal process and spatial extension of the Drought were firstly estimated with ground meteorological and hydrological observations. Then, for the whole region of Sichuan and Chongqing, the remotely sensed Normalized Difference Water In- dex (NDWI) for the summers of 2.01―2.06 were calculated based on 8-day composite MODIS products, which were further used to construct a new water index (Normalized Difference Water Deviation Index, NDWDI) to examine the sensitivity of remote sensing in the Drought. The study showed that the NDWDI is more sensitive to regional drought than other absolute-soil-moisture-based indices. With the new index, the study extracted the spatial-temporal characteristics of the 2.06 Drought, and explored its developing and withdrawing processes, which agreed with related statistics. Compared with ground method of drought observation, the NDWDI-based remote sensing solution of this paper is more pref- erable and practicable in that the local soil properties of water consumption and supply are implicitly taken into account, and the spatial representativity limit of ground observation is circumvented to a degree as satellite remotely senses the earth surface in a way of two-dimensional pixel matrix. So, the NDWDI-based method can be used to monitor regional soil water stress situation more practically and efficiently.

关键词： Sichuan Basin drought Normalized Difference Water Deviation Index response of remote sensing regional scale

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Ultramafic xenoliths in Mesozoic diorite in west Shandong Province

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Science china earth {2. 2004年第6期47卷 489-499页

作者： CHEN Lihui1,2.& ZHOU Xinhua2.1.The Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,china and school of {2. and Space sciences,Peking university,beijing 100871,china 2.Institute of Geology and Geophysics,Chinese Academy of sciences,beijing 10002.,china Correspondence should be addressed to Chen Lihui(email: lihui_chen@***) The Key Laboratory of Orogenic Belts and Crustal Evolution Ministry of Education China and School of Earth and Space Science Peking University Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

Ultramafic xenoliths are common in Tietonggou intrusion, Laiwu, Shandong Prov-ince. Peridotite xenoliths develop two-stage metasomatism popularly: (i) The early metasoma-tism is characterized by intergranular clinopyroxene and phlogopite; (ii) The later metasomatism is characterized by orthopyroxene veins with a few plagioclases and amphiboles. These ul-tramafic xenoliths are thought to be mostly from the crust-mantle transitional zone on the basis of their combination, mineral chemistry, equilibrium temperature, and metasomatic characteristics. Major elements, rare earth elements, and Sr-Nd isotopic composition of the ultramafic xenoliths indicate that there is a petrogenetic relationship between the silica-enriched xenoliths and their host diorites. We propose that such silica enrichment might be an indicator of melt-rock interac-tions in the Mesozoic lithosphere beneath western Shandong.

关键词： ultramafic xenoliths, crust-mantle transitional zone,metasomatism, Tietonggou intrusion, Laiwu.

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Macro-and microscopic mechanical behaviour of flow of coal samples experimentally deformed at high temperatures and pressures

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Chinese Science Bulletin 2005年第S1期50卷 59-66页

作者： LIU Junlai , YANG Guang & MA Rui State Key Laboratory of Geological Processes and mineral resources,{2. university of Geosciences, beijing 100083,{2. Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education,{2. university of Geosciences, beijing 100083,{2. College of {12. sciences, Jilin university, Changchun 130061,{2. State Key Laboratory of Geological Processes and mineral resources China University of Geosciences Beijing China Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education China University of Geosciences Beijing China College of earth sciences Jilin University Changchun China

Coal samples from Qinshui Basin, Shanxi, china are experimentally deformed at temperatures and confining pressures of 2.0 - 500℃and 2.0 - 500 Mpa, strain rate of 0.5×10-5/s and total strain of 10%. The vitrinite reflectance of the coal samples varies from 3.04 to 1.79. It is shown that the strengths of the deformed samples change obviously with coeval increasing temperatures and pressures (T/P). At the experimental range of T/P, the effects of increasing temperature predominate over that of increasing pressure. Microstructural analysis indicates a brittle to ductile transition under experimental T/P conditions from 2.0 to 300℃, and 2.0 to 300Mpa. Brittle deformation microstruc-tures include macroscopic fracture zones and penetrative fracture associations. Elongation, undulose or irregular extinction, deformation lamellae and dynamic recrystallization of grains are the main ductile deformation microstructures. The variation of deformation mechanisms of the experimentally deformed coal samples is related to both the components of coals and T/P conditions. At low T/P, fractures occur in both inertinite and vitrinite of the samples. At higher T/P, crystalline plastic deformations are observed in the inertinite only.

关键词： coal experimental deformation brittle to ductile transition.

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Study on NDVI-T_s space by combining LAI and evapotranspiration

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Science china earth {2. 2006年第7期49卷 747-754页

作者： HAN Lijuan1,2.3, WANG Pengxin4, YANG Hua1,2.3, LIU Shaomin1,2.3 & WANG Jindi1,2.3 1. Research Center for Remote Sensing and GIS, school of Geography, beijing Normal {2., beijing 100875, china 2. State Key Laboratory of Remote Sensing Science, beijing 100875, china 3. beijing Key Laboratory for Remote Sensing of Environment and Digital Cities, beijing 100875, china 4. Department of Information Management, College of Information and Electronic Engineering, china Agricultural {2.,{12., china Research Center for Remote Sensing and GIS School of Geography Beijing Normal University Beijing China State Key Laboratory of Remote Sensing Science Beijing China beijing Key Laboratory for Remote Sensing of Environment and Digital Cities Beijing China Department of Information Management College of Information and Electronic Engineering China Agricultural University Beijing China

This paper focuses on interpreting the different spatial relationships between NDVI and Ts, a triangular or a trapezoid, and on analyzing transformation conditions, the physical and ecological meanings of the vegetation index-surface temperature space as well. Further, we use the Tempera-ture-Vegetation Dryness Index (TVDI) to explain the existent meaning of a triangular space after NDVI reaches its saturated state by employing the relationships between NDVI, LAI and evapotranspiration. The specific relations between NDVI and Ts are useful for describing, validating and updating land surface models.

关键词： NDVI, land surface temperature, evapotranspiration, leave area index.

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Numerical study of the auroral particle transport in the polar upper atmosphere

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Science china(Technological sciences) 2008年第10期51卷 1759-1771页

作者： CAI HongTao1,2. MA ShuYing1,2.& PU ZuYin3 1 school of Electronic Information, Wuhan university, Wuhan 430079,{2. 2.Key Laboratory of Geospace Environment and Geodesy, Ministry of Education of PRC, Wuhan 430079,{2. 3 school of earth and Space sciences, Peking university, beijing 100871,{2. school of Electronic Information Wuhan University Wuhan China Key Laboratory of Geospace Environment and Geodesy Ministry of Education of PRC Wuhan China school of earth and Space {2. Peking University Beijing China

Starting from the Boltzmann equation and with some reasonable assumptions, a one-dimensional transport equation of charged energetic particles is derived by taking account of major interactions with neutral species in the upper atmosphere, including the processes of elastic scattering, the excitation, the ionization and the secondary electron production. The transport equation is numerically solved, for a simplified atmosphere consisting only of nitrogen molecules (N2., to obtain the variations of incident electron fluxes as a function of altitude, energy and pitch angle. The model results can describe fairly the transport characteristics of pre-cipitating auroral electron spectra in the polar upper atmosphere; meanwhile the N2.ionization rates calculated from the modeled differential flux spectra also exhibit good agreements with existing empirical models in terms of several key parameters. Taking the energy flux spectra of precipitating electrons observed by FAST satellite flying over EISCAT site on May 15, 1997 as model inputs, the model-calculated ionization rate profile of neutral atmosphere consists reasonably with that recon-structed from electron density measurements by the radar.

关键词： aurora particle precipitation polar upper atmosphere electron transport equation numerical simulation

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Hydrocarbon Reservoir Model of Glutenite in the Fourth Member of Shahejie Formation in Northern Dongying Depression

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地学前缘 2009年第S1期16卷 136-137页

作者： Hui Liu~(1,2.,Yingchang Cao~3,Yanzhong Wang~3 1.State Key Laboratory of Geological Processes and mineral resources,{2. university of Geosciences,beijing 100083, china. 2.school of Energy resources,{2. university of Geosciences(beijing),beijing 100083,{2. 3.Faculty of Geo-resources and Information,{2. university of Petroleum,Dongying 2.7061,{2.

The glutenite in the fourth member of Shahejie Formation(Es^4) in northern Dongying depression straightforwardly penetrated into the muddy bathyal -abyss *** conditions of reservoir is very superior:(1) the high quality thick bedded oil source rock is developed very well in the Lijin sag and Minfeng sag of the study area,and it has the higher capability of generating hydrocarbon;(2. the

关键词： glutenite hydrocarbon reservoir formation northern Dongying depression fourth member of Shahejie Formation

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3D Integrated Geological Modeling in Tongshan Copper Deposit,Heilongjiang Province,china

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地学前缘 2009年第S1期16卷 282-283页

作者： Gongwen Wang,Limei Wang,Ge Cui,Chengyin Tan,Shanyan Jin school of earth {2. and resources,china university of Geo{2.(beijing),beijing 100083,china.

In this paper,3D-GIS reconstruction and interpolation approach,additional virtual borehole technology and BP network technology are used to explore the concealed ore *** virtual borehole has same function as reality b... 详细信息

关键词： 3D geological modeling virtual borehole BP network mineral exploration Tongshan copper deposit

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Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

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Science china earth {2. 2008年第5期51卷 654-664页

作者： HU Guang1,2. JIN ZhangDong1 & ZHANG Fei3 1 State Key Laboratory of Loess and Quaternary Geology, Institute of earth Environment, Chinese Academy of sciences, Xi’an 710075,{2. 2.Graduate university of the Chinese Academy of sciences, beijing 100049,{2. 3 College of resources and Environmental Science, Nanjing Agricultural university, Nanjing 2.0095,{2. State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China Graduate university of the Chinese Academy of sciences Beijing China College of resources and Environmental Science Nanjing Agricultural University Nanjing China

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan Province, southwest china. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; (2. the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

关键词： ostracod shell molar Sr/Ca ratio molar Mg/Ca ratio environmental response Heqing Basin

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