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1.
高演化海相碳酸盐烃源岩地球化学综合判识--以鄂尔多斯盆地为例 总被引：5，自引：0，他引：5
针对中国海相碳酸盐岩烃源岩的成熟度高、有机质丰度低等特殊性,以鄂尔多斯盆地下古生界为例, 通过微量元素富集系数计算、稀土元素的配分模式、元素和碳同位素等的数理统计分析及三维图解等多元综合分析, 结合必要的有机参数, 反演了盆地烃源岩发育环境, 评价碳酸盐岩烃源岩及其分布. 就鄂尔多斯盆地而言, TOC为0.2%是个重要的界限值, 研究表明: 在TOC>0.2%的层段中, Ba富集,δ13Ccarb正偏移, δ13Corg<-28‰, 反映出古生产力、有机质埋藏量较高, 具较好生烃潜力, 稀土元素分异强, 指示沉降速率低, 有机质保存条件好, 利于烃源岩发育.克里摩里组、乌拉力克组具一定规模, 可视为潜在有效烃源岩. 而TOC＜0.2%的层段, Ba含量低, δ13Ccarb多为负值,δ13Corg为-24‰～-28‰,指示有机质埋藏量低,生烃潜力差,稀土元素分异弱,沉降速率较快,多属浅水高能氧化环境,不利于烃源岩发育.利用无机与有机地球化学方法综合评价高演化海相有潜力的碳酸盐岩烃源岩及分布是可行的. 相似文献
2.
江汉盆地烃源岩中甲基化烷基色瞒系列的分布及其与成熟度的关系 总被引：1，自引：0，他引：1
分析研究了江汉盐湖盆地明钾1井古近系潜江组烃源岩的芳烃馏份中甲基化烷基色瞒的分布和相对组成及其变化.研究结果表明甲基化烷基色瞒系列的分布特征与古沉积环境的盐度关系密切,盐湖相形成的潜一至潜三段烃源岩具有甲基和二甲基烷基色瞒的优势,而非盐湖相形成的潜四段烃源岩呈现出以三甲基烷基色瞒为主,且这一分布特征与表征沉积环境盐度变化特定的生物标志物组合如低的姥植比、高伽马蜡烷指数和富含有机硫化物等具有协同变化.二甲基色瞒比值(5,8-二甲基色瞒/7,8-二甲基色瞒)与烃源岩中镜质体反射率Ro和烃源岩埋藏深度间存在良好的相关关系,且这一关系在镜质体反射率Ro小于0.65%的低成熟阶段特别明显,表明该比值是一个在低成熟阶段对有机质热演化程度的变化十分敏感的芳烃成熟度指标. 相似文献
3.
古近系沙河街组是阳信洼陷最重要的生烃层段.其湖盆充填具阶段性和沉积演化的旋回性,形成了由沙四段、沙三段与沙一段组成的复合生烃系统和不同的地球化学特征.利用Rock-Eval生油岩评价仪、色谱-质谱仪等实验分析技术对不同层系样品进行了地球化学特征分析研究,其中生烃潜力指标包括有机碳含量(TOC)、残余生烃潜量(S1 S2)、氢指数IH、氯仿沥青"A";成熟度指标包括热解峰温Tmax、奇偶优势参数OEP、饱和烃轻重比(C21 C22)/(C28 C29)及∑C21-/∑C22 、镜质体反射率Ro、莫烷/藿烷及甾烷生物标志物参数C29ββ(ββ αα)、C29ααα20S(20S 20R);古环境指标包括异构烷烃参数Pr/Ph、Pr/n-C17、Ph/n-C18及伽马蜡烷等.结果表明,沙四段为弱还原-还原性的半深湖沉积,沉积了一套中等厚度、分布局限的烃源岩(TOC平均为1.5%),其较深位置的烃源岩基本进入成熟阶段,多形成成熟油;沙三段属弱还原-还原性的半深湖-深湖环境,其烃源岩中有机质丰度较高(TOC平均为3.5%),大部分烃源岩处于未成熟-低成熟状态,主要形成未熟油;沙一段为湖水咸化、还原性的半深湖相环境,其烃源岩中有机质丰度高(TOC平均为5%左右),但处于未成熟阶段,主要生成生物气. 相似文献
4.
多属性预测在涠西南凹陷烃源岩研究中的应用 总被引：1，自引：1，他引：0
寻找隐蔽油气藏是目前涠西南凹陷勘探的新领域,优质烃源岩描述是其中一个重要研究课题.涠西南凹陷流沙港组沉积时期为一断陷湖盆,流沙港组二段沉积阶段是湖盆发育的鼎盛时期,中深湖相泥岩或页岩发育,形成了一套良好的区域性烃源岩.油页岩是涠西南凹陷最重要的烃源岩.除油页岩外,流二段还沉积了厚套的中深湖相暗色泥岩,具备非常好的生烃能力.识别和弄清这些暗色泥岩在凹陷中的分布对定量评价涠西南凹陷的生烃潜力具有重要意义.本文尝试将地震多属性预测技术应用于优势烃源岩的研究.首先通过声波时差和电阻率曲线进行多元线性回归,拟合能够体现优势烃源岩特征的有机化学参数总有机碳TOC曲线,利用层位约束消除油页岩对属性优化的干扰作用,最后通过逐步回归的步聪法算法对多地震属性进行优化,找到最佳属性组合,实现TOC数据体的预测,揭示了流二段优质烃源岩的空间展布特征. 相似文献
5.
松辽盆地陆相大规模优质烃源岩沉积环境的地球化学标志 总被引：2，自引：0，他引：2
在松辽盆地晚白垩世青山口组和嫩江组一段选取40块烃源岩样品,利用气相色谱-高分辨飞行时间质谱对烃源岩氯仿抽提物的饱和烃和芳烃化合物开展了定性分析,同时利用气相色谱-质谱对重要生物标志化合物开展了定量检测,目的是寻找陆相大规模优质烃源岩沉积环境的地球化学标志.检测结果显示,烃源岩（Ro〈0.7%）中生物标志物含量或分布的差异,指示不同的沉积环境.青一段烃源岩除萜烷、规则甾烷、4-甲基甾烷含量高外,还具有甲藻甾烷、C31甾烷、芳基类异戊二烯烃含量高的特征,并检测到单质硫和羊毛甾烷等特殊化合物,反映湖泊盐度高、水体分层的泻湖型沉积环境;青二、三段烃源岩各类生物标志化合物的含量较低,反映淡水、浅水的湖泊三角洲沉积环境;嫩一段烃源岩的萜烷、规则甾烷、4-甲基甾烷含量高,但甲藻甾烷、C31甾烷、芳基类异戊二烯烃含量低,反映水体盐度低、分层性差,细菌发育并对有机质改造强烈的淡水-微咸水开放湖泊型沉积环境.综合分析表明,陆相大规模优质烃源岩形成环境的主要地球化学标志是烃源岩C30藿烷含量一般大于1500μg g^-1,伽马蜡烷含量大于190μg g^-1,C27甾烷含量大于200μg g^-1,4-甲基甾烷含量大于100μg g^-1,芳基类异物二烯烃含量大于3μg g^-1,脱羟基维生素E含量大于10μg g^-1. 相似文献
6.
四川盆地的构造、热演化与峨眉山超级地幔柱有密切关系.峨眉山超级地幔柱对四川盆地中二叠统之下的烃源岩热演化有着十分重要的影响.在四川盆地热历史恢复的基础上,研究了峨眉山超级地幔柱对盆地内烃源岩,特别是中二叠统之下的古生界烃源岩热演化的影响.结果表明,中二叠统及下伏烃源岩的热演化受中晚二叠世发生在盆地西南方向的峨眉山超级地幔柱的影响巨大,且具地区差异性.即在靠近峨眉山地幔柱中心的地区,有机质迅速成熟并达到其成熟度的最高值(以H1井为代表),古生界烃源岩迅速进入过成熟,此后未有二次生烃;而远离峨眉山地幔柱的盆地大部分地区,古生界烃源岩在二叠纪以来具有多次生烃过程.中生界烃源岩热演化,主要和前陆盆地阶段的构造过程包括前陆沉积和断裂的逆冲推覆等相关. 在烃源岩有机质成熟度演化史的基础上,从盆地热史和烃源岩热演化的角度指出了下二叠统及之下烃源层在四川盆地不同地区油气勘探中的不同意义. 相似文献
7.
高演化海相碳酸盐烃源岩地球化学综合判识 总被引：11，自引：0，他引：11
针对中国海相碳酸盐岩烃源岩的成熟度高、有机质丰度低等特殊性, 以鄂尔多斯盆地下古生界为例, 通过微量元素富集系数计算、稀土元素的配分模式、元素和碳同位素等的数理统计分析及三维图解等多元综合分析, 结合必要的有机参数, 反演了盆地烃源岩发育环境, 评价碳酸盐岩烃源岩及其分布. 就鄂尔多斯盆地而言, TOC为0.2%是个重要的界限值, 研究表明: 在TOC>0.2%的层段中, Ba富集, δ13Ccarb正偏移, δ13Corg<−28‰, 反映出古生产力、有机质埋藏量较高, 具较好生烃潜力, 稀土元素分异强, 指示沉降速率低, 有机质保存条件好, 利于烃源岩发育. 克里摩里组、乌拉力克组具一定规模, 可视为潜在有效烃源岩. 而TOC＜0.2%的层段, Ba含量低, δ13Ccarb多为负值, δ13Corg为−24‰~−28‰, 指示有机质埋藏量低, 生烃潜力差, 稀土元素分异弱, 沉降速率较快, 多属浅水高能氧化环境, 不利于烃源岩发育. 利用无机与有机地球化学方法综合评价高演化海相有潜力的碳酸盐岩烃源岩及分布是可行的. 相似文献
8.
温度是控制烃源岩有机质生烃的主要因素,构造-热事件下的高温作用对烃源岩的增熟和生烃历程具有显著影响.通过地质分析和磷灰石、锆石裂变径迹、磷灰石U-Th/He低温热年代学数据、火山岩年龄数据分析认为,下扬子中生代存在印支期(T_3-J_2),燕山期(J_3-K_1)构造-热事件,沉积盆地达到最高古热流的时间大约为130~110Ma.古温标镜质体反射率热史反演结果揭示句容地区最高地表古热流达到~94mW·m~(-2),泰兴地区为~78mW·m~(-2),热事件的强度由西至东减弱.基于EASY%Ro模型的生烃史正演结果揭示:寒武系烃源岩在常州地区主生气期为早二叠世晚期至晚三叠世末,在句容、泰兴地区主生气期为晚三叠世-早白垩世.由于T_3-J_(1-2)前陆盆地沉积和早白垩世岩浆活动热事件的双重作用,海相烃源岩有机质在早白垩世末达到最高古地温.虽然K_2-E期间在句容、泰兴和常州部分地区具有一定的沉降幅度,甚至使得部分地区海相烃源岩的埋深超过早期的埋深,但由于K_2以来大地热流降低,海相烃源层地层温度却低于早期的地温,有机质未能普遍进一步增熟生烃,即这些地区不存在大面积的二次生烃. 相似文献
9.
以云南鹤庆盆地HQ孔上部15~55 m沉积物中2个不同种属的介形类壳体为研究对象, 通过比较壳体中Sr/Ca, Mg/Ca之间及其与沉积物Sr含量的关系, 得出以下结论: (1) 壳体Sr/Ca, Mg/Ca首先反映的是该介形类生存的微生态环境; (2) 壳体Sr/Ca较Mg/Ca更好地线性响应水环境的变化, 但当体系中有文石结晶沉降时Sr/Ca不再线性响应湖泊水体盐度的变化; (3) 壳体的Sr/Ca完全受控于湖水盐度及水体中自生碳酸盐矿物的结晶过程, 而壳体中的Mg/Ca则受湖水盐度和温度控制, 实际上温度只是壳体生长速率对壳体Mg/Ca控制的外在表现. 建议在以后的古环境重建及室内培养实验时, 更多地关注沉积物组成及其自生矿物结晶对生物壳体微量元素(如Mg/Ca, Sr/Ca)组成的制约. 相似文献
10.
高演化碳酸盐烃源岩的研究对我国南方油气勘探至关重要．为此,选择下扬子巢湖地区发育较完整的茨苔山栖霞组碳酸盐岩地层,开展沉积学、孢粉相和有机地球化学综合研究;在古环境重建基础上,探讨烃源岩的形成及影响因素．结果表明,栖霞组为二叠纪海侵期形成的生物成因碳酸盐缺氧沉积,纵向上,有机和无机组分变化大．烃源岩的形成是海侵和海侵期间频繁发生的充氧事件引发的高生物产率与缺氧环境综合作用的结果．受自稀释和沉积后作用影响,烃源岩呈非均质分布在多个层段中,累计厚度超过40m,并可通过有机、生物和矿物组成特征进行识别．本次研究认为,碳酸盐岩成为烃源岩并非需要较高的粘土含量．沉积学、孢粉相和有机地球化学方法的结合,为我国高演化碳酸盐烃源岩评价和预测提供了一条更为直接和有效的途径． 相似文献
11.
LI GuoShan WANG YongBiao LU ZongSheng LIAO Wei SONG GuoQi WANG XueJun XU XingYou 《中国科学:地球科学(英文版)》2014,57(5):976-987
Gypsum-salt rocks and coccolith calcareous shale are widely deposited in the lower part of the Paleogene Shahejie Formation in the Dongying Sag,Shandong Province.The gypsum-salt rock is believed to be formed during the earlier deposition in salt lake,while the overlying coccolith shale in saline lake with relatively low salinity.By comparing the lake environment and lacustrine microbial communities between ancient and recent lakes,cyanobacteria are regarded as the main representative of productivity during the formation of gypsum-salt strata series,with the annual productivity of 1500-2000 gC m-2 yr-1.Based on the research of ultramicrofossils in the calcareous shale,coccolith is considered as the main contributor to the productivity during the formation of calcareous shale.On the basis of statistic data of sedimentary rates,shale laminations,and coccolith fossils in each lamination,the quantitative value of productivity is calculated,with the annual productivity of 2250-3810gC m-2 yr-1(averagely 3120 gC m-2 yr-1).Statistic data of large amount of pyrite framboids indicate that the lower water column was persistently in sulfidic or anoxic conditions during the deposition of gypsum-salt strata series,but it changed to be dysoxic when the coccolith calcareous shale was deposited.Both of these water conditions are favorable for the preservation of organic matter.It is estimated that the organic carbon burial efficiency of the Lower Paleogene salt lakes and saline lakes of Dongying Depression is about 10%-15%,which is calculated and analyzed using the multi-parameter geobiological model. 相似文献
12.
The geobiological formation process of the marine source rocks in the Middle Permian Chihsia Formation of South China 总被引：2，自引：0，他引：2
The Chihsia Formation is one of the four sets of regional marine hydrocarbon source rocks from South China.In the past two decades,detailed geochemical and sedimentological studies have been carried out to investigate its origination,which have demonstrated that the high primary productivity plays a primary role in the deposition of sediments enriched in the organic matter.However,the mechanism of this high productivity and the path of the deposition and burial of the organic matter have always been a mystery.Based on the previous studies on the Shangsi Section in Guangyuan City,Sichuan Province,we proposed that the development of the equatorial upwelling due to the sea level rise is responsible for the relatively high productivity in the Chihsia Formation.The sea waters with high nutrient were transported by the sub-surface currents along the equator.High organic carbon flux was deposited on the deeper shelf,and then decomposed by bacteria,leading to the occurrence of anaerobic respiration.The metabolism of the microorganisms consumed the dissolved oxygen in waters,which was in favor of the preservation of the organic matter.This suggested geobiological model integrating with paleoclimatology,paleoceanography and geomicrobiology will help us to understand the causes of this particular sedimentary sequence. 相似文献
13.
Luo JingLan Li Jian Yang BingHu Dai YaQuan Li Bo Han YongLin Wang HaiHong Du JinLiang 《中国科学D辑(英文版)》2007,50(2):75-90
Study indicates that the major paleocurrent and source direction for the Chang 8 Member of the Yangchang Formation, Upper Triassic in the Xifeng area of the southwestern Ordos Basin derived from the southwest direction with the southeast source as the subordinate one. While the Chang 6 Member was influenced not only by the same source as that of the Chang 8 Member from the southwest and the southeast direction, but also affected by the northeast and the east provenance around the Ordos Basin, based upon measurement of paleocurrents on outcrops located in the periphery Ordos Basin, analysis of framework grains and heavy minerals in sandstones of the Chang 6 and Chang 8 Members and their spatial distribution in the study area, combined with characteristics of trace elements and rare-earth elements of mudstones and of a small amount of sandstones in the Xifeng area and outcrops in margin of the Ordos Basin. The Yuole-Xuanma-Gucheng-Heshui-Ningxia region located in the northeastern and the eastern Xifeng area was the mixed source area where the southwest, southeast, northeast and the east sources were convergent till the Chang 6 Member was deposited. The rare earth elements of the Chang 6 and Chang 8 Members are characterized by slight light rare earth-elements (LREE) enrichment and are slightly depleted in heavy rare earth-elements (HREE) with weak to moderate negative abnormal Eu, resulting in a right inclined REE pattern, which implies that the source rocks are closely related with better differential crust material. Analysis on geochemical characteristics of the mudstones and sandstones, features of parent rocks in provenance terranes and tectonic settings shows that source rocks for the Chang 8 Member mainly came from metamorphic and sedimentary rocks in transitional continental and basement uplift terranes with a small amount of rocks including metamorphic, sedimentary and igneous rocks coming from mixed recycle orogenic belt located in the southwest margin of the Ordos basin. Rocks in the crystalline basement and the overlying sedimentary cover in a basement uplift setting in the northeast periphery of the basin also contributed a part of the sources for the Chang 6 Member, in addition to the sources deriving from transitional continental and basement uplift terranes in the southwest margin of the basin. Parent rocks of the provenance terrane in the northeast margin of the Ordos Basin are characterized by having more felsic rocks. 相似文献
14.
SHAN XuanLong LI JiYan CHEN ShuMin RAN QingChang CHEN GuiBiao LIU Chao 《中国科学:地球科学(英文版)》2013,56(11):1926-1933
This paper reports the analysis on cores and rock slices,data on seismic and logging activities,characteristics of core samples,and the paleogeographic background of the Yingcheng Formation of the Xujiaweizi faulted depression in the Songliao Basin.The results show that some of the volcanic rocks were formed during subaquatic eruptions.These subaqueous volcanic rocks are further characterized by the interbedded black mudstone and tuffite,the presence of double-layer perlite enclosing aphyric or sparsely phyric rhyolite,the presence of a bentonite layer,and the coefficient of oxidation(Fe2O3/FeO).The types of rocks are volcanic breccia,lava breccias,perlite,rhyolite,tuff and sedimentary tuff.The subaquatic eruptions are distributed mainly in Wangjiatun,Shengping,Xuxi,Xuzhong,and Xudong.The XS-1 area is the most typical.The organic abundance of overburden mud rocks within the volcanic rocks of the Yingcheng Formation indicates that these rocks represent high-quality source rocks.The analysis also shows that continental subaquatic volcanic eruptions provide a rich supply of minerals and energies for the lake basin and increase the organic matter content in the water.Moreover,the water differentiation provides a good reducing environment for the conservation of organic matter,and is beneficial for the formation of high-quality source rocks.Finally,we propose a hypothesis to describe the mode of subaquatic eruptions and the formation of high-quality source rocks. 相似文献
15.
Late Cretaceous paleoenvironment and lake level fluctuation in the Songliao Basin,northeastern China
Study of Late Cretaceous lacustrine sedimentary strata in the eastern Songliao Basin, China revealed that the paleoclimate was relatively arid and hot during sedimentation of the upper Santonian of the Yaojia Formation, but became relatively humid and warm during deposition of the lower Campanian Nenjiang Formation. The upper Yaojia Formation was deposited in a freshwater lake environment, while the lower Nenjiang Formation was deposited in a slightly brackish to brackish environment. The average total organic carbon content in the upper Yaojia Formation is 0.15%, while the hydrogen index is 36 mgHC/gTOC, implying poor source rock for oil generation and the organic matter comprised of a mixture of woody and herbaceous organic matter. In contrast, the hydrogen index of oil shale and black shale of the lower Nenjiang Formation is 619 mgHC/gTOC, and total organic carbon content on average is 3.37%, indicating a mixed algae and herbaceous source of kerogen and an increase in aquatic bioproductivity. The black shale and oil shale have low Pristane/Phytane and C29 5α,14α,17α(H) ? stigmastane 20R/(20R + 20S) ratios, with maximum concentration of n‐alkanes at n‐C23, implying an anoxic depositional environment with algae, bacteria and higher plants providing most of the organic matter. Relatively abundant gammacerane and a higher Sr/Ba ratio in the oil shales suggest the presence of brackish water and development of salinity stratification in the lake. During sedimentation of the upper Yaojia through the lower Nenjiang Formations, the level of Songliao lake increased and a deep‐lake environment was formed with bottom waters being oxygen depleted. Concomitantly, as the lake deepened bottom conditions were changing from oxic to anoxic, and the input of organic matter changed from predominantly higher plants to a mixture of bacteria, algae and higher plants providing favorable conditions for oil source rock accumulation. 相似文献
16.
ZHAO Wenzhi WANG Zhaoyun HE Haiqing ZHANG Mingjie WANG Hongjun WANG Yunpeng & QIN Yong . Research Institute of Petroleum Exploration & Development PetroChina Beijing China . PetroChina Exploration & Production Beijing China . Department of Geology Lanzhou University Lanzhou China . Guangzhou Geochemical Institute Chinese Academy of Sciences Guangzhou China . China University of Mining Technology Xuzhou China 《中国科学D辑(英文版)》2005,48(4):441-453
It has been proven in exploration practice that thecarbonates in China not only can generate hydrocar-bons, but also form commercial reservoirs. The car-bonates are different from clastic rocks in view of theirdeposition environment as well as their sedimentaryand diagenetic processes. Therefore, the evaluationcriteria and hydrocarbon generation mechanism forcarbonates can not be the same as that for clasticrocks, and it is important to establish a special hydro-carbon generation mechanism and… 相似文献
17.
烃源岩的定量地震刻画对于勘探开发区块的优选、盆地油气资源量的估算都具有重要意义.陆相沉积环境下的浅湖或半深湖相的烃源岩横向变化快,其空间展布需要依靠钻井约束下的反射地震进行刻画,但是其地震弹性特征与岩性和有机质含量的映射关系呈现高度非线性化,因而很难利用传统基于地震岩石物理模型驱动的烃源岩地震预测方法进行有效刻画.本文以低勘探区的东海盆地长江坳陷为例,提出了一种在数据驱动的机器学习框架下,综合利用地质约束、钻井录井、测井、地球化学和叠前地震数据进行烃源岩的定量地震刻画的工作流程.其核心思想是利用随机森林集成学习算法对小样本数据表现优异的特征,以井位处的测井弹性数据(纵波速度和密度)、岩性、地球化学标定的总有机碳含量(TOC)为样本标签数据,在地质导向约束下通过随机森林算法生成学习网络,并将该网络与叠前地震反演结果相结合,采取先预测泥岩再预测总有机碳含量的“两步走”策略,完成对烃源岩空间分布及其非均质性的定量地震刻画,并对预测结果的不确定性进行评价.测试结果显示,随机森林算法相较于其他的机器学习算法能够更准确的识别陆相沉积地层的泥岩,并比传统的利用阻抗转化方法获得更可靠的总有机碳含量预测结果. 相似文献
18.
Distribution and geological significance of 17α(H)-diahopanes from different hydrocarbon source rocks of Yanchang Formation in Ordos Basin 总被引：2，自引：0，他引：2
Based on GC-MS testing data of many saturated hydrocarbon samples, 17α(H)-C30 diahopanes (C30
*) are extensively distributed in the lacustrine hydrocarbon source rocks of the Yanchang Formation in Ordos Basin, but show
remarkable differences in relative abundance among various source rocks. Generally, Chang 7 high-quality source rock (oil
shale) developed in deep lake anoxic environment shows lower C30
* content, whereas Chang 6–9 dark mudstone developed in shallow to semi-deep lake, sub-oxidizing environment shows relatively
high to high C30
* value. Particularly, Chang 7 and Chang 9 black mudstones in Zhidan region in the northeast of the lake basin show extremely
high C30
* value. A comparative analysis was made based on lithology, organic types and various geochemical parameters indicative of
redox environment, and the results indicate that environmental factors such as redox settings and lithology are key factors
that control the C30
* relative abundance, while organic types and maturity may be minor factors. High to extremely high C30
* values are indicative of sub-oxidizing environment of fresh-brackish water and shallow to semi-deep lake. Therefore, research
on C30
* relative content and distribution in lacustrine hydrocarbon source rocks in the Yanchang Formation, especially on the difference
in C30
* between Chang 7 high-quality source rocks (oil shale) and Chang 6–91 source rocks (dark mudstone), will provide an important approach for classification of Mesozoic lacustrine crudes and detailed
oil-source correlation in the basin.
Supported by National Natural Science Foundation of China (Grant No. 40773028) 相似文献
19.
As revealed from recent drilling and organic geochemical testing and research, a series of lacustrine high-grade hydrocarbon source rocks was discovered in the upper section of the Chang 9 oil reservoir member of upper Triassic in Ordos Basin. The hydrocarbon source rocks show average TOC content as high as 5.03%, average bitumen "A" content as high as 0.8603%, and good quality organic precursors, which are of the sapropelic type mainly derived from lower aquatic plants and have reached the thermal evolution stage featured by oil-producing climax. Generally the lacustrine high-grade hydrocarbon source rocks were developed in local depressions of a lake basin, and the Chang 91 member was particularly formed in a depositional environment characterized by fresh water to weakly saline water, weakly oxidizing to weakly reducing setting and semi-deep lake facies, as was demonstrated by a variety of organic to inorganic geochemical parameters. As a result, high productivity constitutes the principal controlling force for generation of this series of high-grade hydrocarbon source rocks. Deposition of thinly-bedded and laminated tuffs as well as positive Eu anomaly corroborate the possible occurrence of anoxic geological event closely related to contemporaneous volcanic eruption, which would play a key part in development of the Chang 91 member of high-grade hydrocarbon source rocks. 相似文献