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措勤盆地林子宗群火山岩地球化学特征 总被引：7，自引：0，他引：7
青藏高原措勤盆地新生代火山活动十分强烈,以古近纪林子宗群火山岩为代表,主要分布在盆地中央隆起带的冈底斯构造岩浆岩带中,在北部坳陷带中仅有零星分布。林子宗群火山岩主要由安山岩、流纹岩、中酸性熔岩和火山碎屑岩组成。岩石化学研究表明属钙碱－高钾钙碱系列;岩石地球化学研究表明,木子宗群火山岩具岛弧火山岩特点,为喜马拉雅板片与冈底斯－念青唐古拉板片碰撞作用的产物。 相似文献
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川东北地区酸性气体中CO2成因与TSR作用影响 总被引：3，自引：0，他引：3
通过对川东北地区52个天然气样品化学组分和稳定碳同位素分析,天然气以烃类气体为主,且甲烷占绝对高含量,重烃气体甚微,干燥系数C1/C1+为0.989～1.0。非烃气体H2S和CO2含量变化较大,当二者含量大于5.0％时,具有较好的正相关性。川东北地区天然气中CO2主要包括碳酸盐岩热分解和TSR作用,其中碳酸盐岩热分解生成的CO2含量一般小于5.0％,13CCO2值小于-2‰,且CO2含量与13CCO2值具有正相关性;而TSR作用生成的CO2含量大于5.0％,13CCO2值多大于-2‰,且CO2含量与13CCO2值具有较弱的负相关性。CH4/CO2比值和（H2S+CO2）/（H2S+CO2+∑C1-3）比值能够较好地反映TSR作用程度;当CH4/CO2比值和（H2S+CO2）/（H2S+CO2+∑C1-3）比值分别小于10和大于0.1时,随着TSR作用增强,CH4/CO2比值减少,而（H2S+CO2）/（H2S+CO2+∑C1-3）比值呈指数增加。同时,遭受TSR作用改造的天然气具有较高CO2含量和重的13CCO2,造成13CCO2值与实验结果不一致性的可能原因是在TSR反应过程中部分CO2与硫酸盐中Mg2+、Fe2+和Ca2+等金属离子以碳酸盐的形式沉淀且残余的重碳同位素组成的CO2与酸性气体腐蚀碳酸盐储层形成的CO2相混合。 相似文献
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WU Xiaoqi LIU Quanyou LIU Guangxiang WANG Ping LI Huaji MENG Qingqiang CHEN Yingbin ZENG Huasheng 《《地质学报》英文版》2017,91(6):2200-2213
The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is mainly composed of methane (88.99%–98.01%), and the dryness coefficient varies between 0.908 and 0.997. The gas generally displays positive alkane carbon and hydrogen isotopic series. The geochemical characteristics and gas-source correlation indicate that the gases stored in the 5~(th) member of the Upper Triassic Xujiahe Formation are coal-type gases which are derived from source rocks in the stratum itself. The gases reservoired in the 4~(th) member of the Xujiahe Formation and Jurassic strata in the Xinchang gas field are also coal-type gases that are derived from source rocks in the 3~(rd) and 4~(th) members of the Xujiahe Formation. The gases reservoired in the 2~(nd) member of the Upper Triassic Xujiahe Formation are mainly coal-type gases with small amounts of oil-type gas that is derived from source rocks in the stratum itself. This is accompanied by a small amount of contribution brought by source rocks in the Upper Triassic Ma'antang and Xiaotangzi formations. The gases reservoired in the 4~(th) member of the Middle Triassic Leikoupo Formation are oil-type gases and are believed to be derived from the secondary cracking of oil which is most likely to be generated from the Upper Permian source rocks. 相似文献
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A low-mature coal (Ro=0.4%, from the Manjia'er depression, Tarim Basin, China) was subjected to closed system pyrolysis, in sealed gold tubes,
under isothermal temperature conditions. The carbon isotopic compositions of the pyrolyst fractions (hydrocarbon, CO2, CO, etc.) at two temperature points (350°C and 550°C) were measured. The results showed that {ie359-1} value is generally
heavier at 350°C than that at 550°C, because the high abundance of CO generated at low temperature would greatly influence
{ie359-2} value, and the retention time of CO in gas chromatograph is close to that of CH4. But CO is formed through chemical reaction of the oxygen-containing functional group −C=O, e.g. lactones, ketones, ether,
etc. at low temperature, while CO2 comes mainly from decarboxylization.
The carbon isotopic composition of coal gas from Lanzhou Coal Gas Works was definitely different from that of thermally pyrolysed
products from coal. The {ie359-3} value of coal gas was abnormally heavier than {ie359-4}. At the same time, the reversed
sequence ({ie359-5}) of {ie359-6} and {ie359-7} happened. The bond energy of free ions generally decides the sequence of generation
of hydrocarbon fractions according to the chemical structure, whereas the stability of pyrolysate fractions and their carbon
isotope fractionation are affected by the C−C bond energy.
This study was supported by the National Basic Research (973) Program of China (No. 2001CB209102). 相似文献
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通过对塔里木盆地满加尔凹陷低成熟煤岩在开放在线程序升温体系的热模拟实验,获得煤岩在不同温度点的热分解产物CH4、CO和N2,并对模拟后残留产物进行了镜质体反射率测试,建立了镜质体反射率与对应受热温度之间的关系。煤岩镜质体反射率与热温度之间的二阶关系表达为:Ro=0.0014×T+0.109,r=0.9931(Ro<0.6%);Ro=0.0067×T-1.5855,r=0.9996(Ro>0.6%)。通过上述方程建立CH4/N2值与煤岩镜质体反射率之间的对应关系,并利用CH4/N2值对塔里木盆地库车坳陷天然气热成熟度进行了预测。预测结果与实际地质分析结果相吻合,说明CH4/N2值可以作为塔里木盆地煤成气热成熟度预测指标应用于油气勘探中。 相似文献
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青藏措勤盆地早白垩世多巴组烃源岩评价 总被引：3，自引：0，他引：3
该区早白垩世多巴组烃源岩岩石类型、有机质丰度、有机质类型、有机质热演化程度等方面研究表明,多巴组烃源岩有机质丰度偏低,有机质以腐泥型和腐殖腐泥型为主,有机质的热演化以高成熟为主,总体评价为较差烃源岩．该成果为在措勤盆地进一步开展油气勘探提供可靠的地质资料。 相似文献
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Jinxing Dai Caineng Zou Jian Li Yunyan Ni Guoyi Hu Xiaobao Zhang Quanyou Liu Chun Yang Anping Hu 《International Journal of Coal Geology》2009,80(2):124-134
Coal-derived hydrocarbons from Middle–Lower Jurassic coal-bearing strata in northwestern China are distributed in the Tarim, Junggar, Qaidam, and Turpan-Harmi basins. The former three basins are dominated by coal-derived gas fields, distributed in Cretaceous and Tertiary strata. Turpan-Harmi basin is characterized by coal-derived oil fields which occur in the coal measures. Based on analysis of gas components and carbon isotopic compositions from these basins, three conclusions are drawn in this contribution: 1) Alkane gases with reservoirs of coal measures have no carbon isotopic reversal, whereas alkane gases with reservoirs not of coal measures the extent of carbon isotopic reversal increases with increasing maturity; 2) Coal-derived alkane gases with high δ13C values are found in the Tarim and Qaidam basins (δ13C1: − 19.0 to − 29.9‰; δ13C2: − 18.8 to − 27.1‰), and those with lowest δ13C values occur in the Turpan-Harmi and Junggar basins (δ13C1: − 40.1 to − 44.0‰; δ13C2: − 24.7 to − 27.9‰); and 3) Individual specific carbon isotopic compositions of light hydrocarbons (C5–8) in the coal-derived gases are lower than those in the oil-associated gases. The discovered carbon isotopic reversal of coal-derived gases is caused by isotopic fractionation during migration and secondary alteration. The high and low carbon isotopic values of coal-derived gases in China may have some significance on global natural gas research, especially the low carbon isotope value of methane may provide some information for early thermogenic gases. Coal-derived methane typically has much heavier δ13C than that of oil-associated methane, and this can be used for gas–source rock correlation. The heavy carbon isotope of coal-derived ethane is a common phenomenon in China and it shed lights on the discrimination of gas origin. Since most giant gas fields are of coal-derived origin, comparative studies on coal-derived and oil-associated gases have great significance on future natural gas exploration in the world. 相似文献
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Quanyou LIU Peng LI Zhijun JIN Yuewu SUN Guang HU Dongya ZHU Zhenkai HUANG Xinping LIANG Rui ZHANG Jiayi LIU 《中国科学:地球科学(英文版)》2022,65(1):118-138
Lacustrine shale is an important target for the exploration of unconventional oil and gas in China beyond marine shale gas.However,the formation environment of lacustrine shale differs from that of marine shale,resulting in a different reservoir composition,organic matter,oil and gas content,and hydrocarbon mobility.In this study,the Chang 7 shale of the Yanchang Formation in the Ordos Basin was used to analyze the effect of volcanic activity on the paleoproductivity and preservation conditions during the formation of lacustrine shale.The results show that algae and bacteria were developed before the eruption.After the eruption,the number of bacteria declined,but the increased prosperity of algae reflects that the volcanic activity enhanced ancient productivity.The sulfate generated by volcanic activity promotes bacterial sulfate reduction,and the produced H2S leads to a strong reducing environment in the waterbody,which is conducive to the preservation of organic matter.Organic geochemical analysis shows that the black shale in the shale strata has a high total organic carbon(TOC)content and strong hydrocarbon generation potential,whereas the tuff has a low TOC content and can scarcely generate hydrocarbons,indicating that the tuff deposited by volcanic activity cannot be considered as effective source rock.In terms of storage space,shale is mainly laminar and dispersed,and it includes organic and inorganic pores.The development of organic pores is affected by thermal maturity,whereas inorganic pores mainly occur between detrital particles and crystals.Tuff is mainly supported by heterogeneous matrix and associated with alteration.Its pores include inter-and intragranular mineral pores.The development of tight sandstone pores is affected by compaction,cementation,and dissolution,which mainly consist of intra-and intergranular pores.The Chang 7 lacustrine shale generally contains oil,but different lithologies have different oil drainage efficiencies.Sandstone and shale exhibit the best and worst oil drainage efficiency,respectively.It is mainly affected by the pore size distribution,fluid properties,and rock wettability.Therefore,the development of shale oil should mainly focus on lacustrine shale formations with interbeds.The mutual dissolution of organic matter and hydrocarbons in the shale section leads to the poor mobility and difficult development of hydrocarbons. 相似文献
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旅游流流量位序-规模分布变化及其机理——以四川省为例 总被引：8，自引：0，他引：8
以四川省为实证区,借助齐夫(Zipf)定律,证明了国内旅游流和入境旅游流的流量位序—规模分布均满足齐夫法则。在此基础上进一步分析了1996~2005年各年旅游流流量位序—规模双对数坐标图上无标度区范围、标度分段特征和各标度区内部流量密度分布的变化规律。结果表明,无论是国内还是入境旅游流,其流量规模分布结构的无标度区范围都呈逐年扩大趋势,但其空间分形结构和分布形态变化却有较大差异,其中国内旅游流的分形结构由最初的局部分形演化为单分形,再由单分形退化为双分形结构;空间分布形态则由帕雷托(Pareto)分布模式向对数正态分布模式转变。入境旅游流的分形结构没有出现双分形退化,其空间分布形态也基本保持不变,仍呈帕雷托分布模式。两种旅游流规模分布不同步变化的主要原因可能是交通条件改善和新旅游景区(点)开发对国内旅游者和入境旅游者的目的地选择行为的影响不一致造成的。 相似文献