Most vein minerals deposited in fractures of the Jialingjiang Formation from Libixia section, Hechan area include a large amount of saddle dolomite and accompanying celestite, calcite and fluorite. This study analyzed...Most vein minerals deposited in fractures of the Jialingjiang Formation from Libixia section, Hechan area include a large amount of saddle dolomite and accompanying celestite, calcite and fluorite. This study analyzed the nature, source, evolution of the fluids by plane-light petrography, fluid-inclusion methods, cathodoluminescence images, and stable isotopic compositions. The homogenization temperatures of two-phase aqueous fluid inclusions in dolomite range between 100 and 270℃. Combined with the jlSO data, it is suggested that the fluid responsible for the precipitation of fracture fillings have δ18O values between 10%o and 18‰ （relative to SMOW）. The saddle dolomite and the accompanying minerals were the result of activity of dense brines at elevated temperatures. Moreover, analysis shows that the fluid was derived from a mixture of marine-derived brine and deeper circulating flow. This fluid was enriched in Sr during diagenesis and formed celestite in fracture and for regional mineralization. Dissolution of saddle dolomite was attributed to the cooling of Mg/Ca-decreased fluids, which may relate to a leaching of gypsum to celestite in surrounding carbonates.展开更多
The sequence of the densification and hydrocarbon charging of the Xu2 reservoir in the Anyue–Hechuan area of Central Sichuan Basin is discussed.The diagenetic sequence is considered a time line to determine the histo...The sequence of the densification and hydrocarbon charging of the Xu2 reservoir in the Anyue–Hechuan area of Central Sichuan Basin is discussed.The diagenetic sequence is considered a time line to determine the historical relationship between the densification process and the hydrocarbon charging of the Xu2 reservoir in the study area:Early diagenetic stage B(the first stage of hydrocarbon charging,which was about 200–160 Ma ago,with a porosity of about 20%,consolidated and not tight)→middle diagenetic stage A(the second stage of hydrocarbon charging,which was about 140–120 Ma ago,with a porosity of 10%–20%and relatively tight)→middle diagenetic stage B(the third stage of hydrocarbon charging,which was about 20–5 Ma ago,with a porosity of 6%–10%and tight;However,fractures have developed).The study results prove that large-scale hydrocarbon charging and accumulation completed before the densification of the Xu2 reservoir,showing that the Upper Triassic Xujiahe Fm unconventional tight reservoir in the Sichuan Basin is prospective for exploration.展开更多
合川地区上三叠统须家河组须二段储层中蕴藏着丰富的天然气资源,但由于地层埋深过大,压实、压溶作用强烈,各种填隙物阻塞储层孔隙及喉道等因素的影响,该地区的须二段储层已经非常致密,对其中的天然气进行开采难度比较大、所需成本比较...合川地区上三叠统须家河组须二段储层中蕴藏着丰富的天然气资源,但由于地层埋深过大,压实、压溶作用强烈,各种填隙物阻塞储层孔隙及喉道等因素的影响,该地区的须二段储层已经非常致密,对其中的天然气进行开采难度比较大、所需成本比较高。然而勘探开发与实验室研究皆发现,研究区须二段普遍致密的砂岩储层中仍然存在着一部分可以提供高产气流的优质储层。在当前全球油价低靡的能源环境下,对这部分储层展开研究意义重大。鉴于此,通过岩心观察、铸体薄片镜下鉴定、扫描电镜等实验分析手段对该地区须二段孔隙度大于9%、渗透率大于0.09 m D的优质储层储集空间特征进行了研究;根据研究结果将优质储层分为了原生孔隙型、次生孔隙型、混合孔隙型和裂缝—孔隙型4种类型,并分析了每一类型优质储层形成的主控因素。展开更多
The relationship between species diversity and ecosystem function is a hot topic in ecology and environics.This paper investi-gates the evolution of diversity of the late Middle Permian brachiopods community in Hechua...The relationship between species diversity and ecosystem function is a hot topic in ecology and environics.This paper investi-gates the evolution of diversity of the late Middle Permian brachiopods community in Hechuan,Chongqing,China,and dis-cusses the relationship between species diversity and community productivity in terms of the geohistorical development.This paper shows that the species diversity is externalized by several indexes,and the relationship between diversity and productiv-ity is too complex to be described by a single assumption.The relationship between species diversity and community produc-tivity is restricted by environment and community evolution.When the community succeeds normally,the relationship be-tween species richness index,species diversity index,and species evenness index to productivity is in linear dependence rela-tion to each other,which is met with the third assumption.But,when the environment interference surpasses the bearing capa-bility of the community,not only the community succession will be terminated and be replaced by another one,but also the relationship between species richness index,species diversity index,and species evenness index to productivity is also in-versed to negative correlation by the interference from environment.Only the relationship between ecological dominance and productivity is in linear dependence relation to each other and approximately met with the third assumption.It is illustrated that the assumption that the productivity is in linear dependence relation with diversity should be established on the presupposition that the community succession is normal.展开更多
基金supported by the National Natural Science Foundation of China(grants no.41272130 and 41172099)support provided by Key Laboratory for Sedimentary Basin and Oil and Gas Resources of MLR(grant no.zdsys2014003)
文摘Most vein minerals deposited in fractures of the Jialingjiang Formation from Libixia section, Hechan area include a large amount of saddle dolomite and accompanying celestite, calcite and fluorite. This study analyzed the nature, source, evolution of the fluids by plane-light petrography, fluid-inclusion methods, cathodoluminescence images, and stable isotopic compositions. The homogenization temperatures of two-phase aqueous fluid inclusions in dolomite range between 100 and 270℃. Combined with the jlSO data, it is suggested that the fluid responsible for the precipitation of fracture fillings have δ18O values between 10%o and 18‰ （relative to SMOW）. The saddle dolomite and the accompanying minerals were the result of activity of dense brines at elevated temperatures. Moreover, analysis shows that the fluid was derived from a mixture of marine-derived brine and deeper circulating flow. This fluid was enriched in Sr during diagenesis and formed celestite in fracture and for regional mineralization. Dissolution of saddle dolomite was attributed to the cooling of Mg/Ca-decreased fluids, which may relate to a leaching of gypsum to celestite in surrounding carbonates.
基金Project(41372141) supported by the National Natural Science Foundation of ChinaProject(2008ZX05001–05–01) supported by Special and Significant Project of National Science and Technology,China
文摘The sequence of the densification and hydrocarbon charging of the Xu2 reservoir in the Anyue–Hechuan area of Central Sichuan Basin is discussed.The diagenetic sequence is considered a time line to determine the historical relationship between the densification process and the hydrocarbon charging of the Xu2 reservoir in the study area:Early diagenetic stage B(the first stage of hydrocarbon charging,which was about 200–160 Ma ago,with a porosity of about 20%,consolidated and not tight)→middle diagenetic stage A(the second stage of hydrocarbon charging,which was about 140–120 Ma ago,with a porosity of 10%–20%and relatively tight)→middle diagenetic stage B(the third stage of hydrocarbon charging,which was about 20–5 Ma ago,with a porosity of 6%–10%and tight;However,fractures have developed).The study results prove that large-scale hydrocarbon charging and accumulation completed before the densification of the Xu2 reservoir,showing that the Upper Triassic Xujiahe Fm unconventional tight reservoir in the Sichuan Basin is prospective for exploration.
文摘合川地区上三叠统须家河组须二段储层中蕴藏着丰富的天然气资源,但由于地层埋深过大,压实、压溶作用强烈,各种填隙物阻塞储层孔隙及喉道等因素的影响,该地区的须二段储层已经非常致密,对其中的天然气进行开采难度比较大、所需成本比较高。然而勘探开发与实验室研究皆发现,研究区须二段普遍致密的砂岩储层中仍然存在着一部分可以提供高产气流的优质储层。在当前全球油价低靡的能源环境下,对这部分储层展开研究意义重大。鉴于此,通过岩心观察、铸体薄片镜下鉴定、扫描电镜等实验分析手段对该地区须二段孔隙度大于9%、渗透率大于0.09 m D的优质储层储集空间特征进行了研究;根据研究结果将优质储层分为了原生孔隙型、次生孔隙型、混合孔隙型和裂缝—孔隙型4种类型,并分析了每一类型优质储层形成的主控因素。
基金supported by State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology,CAS) (Grant No.123115)the Fundamental Research Funds for the Central Universities"(Grant No.2010LKDZ01)
文摘The relationship between species diversity and ecosystem function is a hot topic in ecology and environics.This paper investi-gates the evolution of diversity of the late Middle Permian brachiopods community in Hechuan,Chongqing,China,and dis-cusses the relationship between species diversity and community productivity in terms of the geohistorical development.This paper shows that the species diversity is externalized by several indexes,and the relationship between diversity and productiv-ity is too complex to be described by a single assumption.The relationship between species diversity and community produc-tivity is restricted by environment and community evolution.When the community succeeds normally,the relationship be-tween species richness index,species diversity index,and species evenness index to productivity is in linear dependence rela-tion to each other,which is met with the third assumption.But,when the environment interference surpasses the bearing capa-bility of the community,not only the community succession will be terminated and be replaced by another one,but also the relationship between species richness index,species diversity index,and species evenness index to productivity is also in-versed to negative correlation by the interference from environment.Only the relationship between ecological dominance and productivity is in linear dependence relation to each other and approximately met with the third assumption.It is illustrated that the assumption that the productivity is in linear dependence relation with diversity should be established on the presupposition that the community succession is normal.
