泌阳凹陷古近系核三段页岩层有机质富集规律
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摘要
泌阳凹陷古近系核三段泥页岩是主要烃源岩,可划分出5套富有机质泥页岩层,页岩层系中有机质在层序地层格架内呈规律性分布。利用常量、微量元素和生物标志化合物等参数分析了5号和3号页岩层内有机质富集及其与沉积环境(气候、盐度、生产力、氧化还原条件)的相关性,并探讨了层序地层格架内有机质富集的主控因素(生产力和保存条件)。研究表明:15号页岩层有机质主要富集于湖扩体系域中下部,3号页岩层有机质主要富集于最大湖泛面附近;2浊流活动对沉积层中有机质含量起稀释作用,导致深凹周缘区有机碳质量分数变化较大且频繁,但深凹中心区变化相对较小;35号和3号页岩层有机碳质量分数变化与氧化还原指标(V/Cr,Pr/Ph)均呈线性相关,其中3号页岩层有机碳质量分数变化还与古生产力指标(Cu、Ni)呈较好的相关性,表明干旱炎热气候下咸化水体的盐度分层有利于形成良好的保存条件,是5号页岩层有机质富集的关键,而温暖潮湿气候下藻类勃发对应的高生产力水平,以及湖盆深处缺氧底水环境决定了3号页岩层有机质的富集。
The shales in He-3Member of Paleogene Hetaoyuan Formation in the Biyang Depression mainly consists of hydrocarbon source rocks,and can be divided into five organic-matter-rich intervals(ORIs),where organic matter(OM)is distributed regularly in the sequence stratigraphic framework.The present work addresses the distribution of major elements,trace elements and biomarker parameters of shales from5 th and 3rd ORIs for discussion of the relationships between the enrichment of organic matter and the changes of climate,salinity,redox condition,productivity,and identification of the mechanism of OM accumulation in the sequence stratigraphic framework.The results show that OM of 5th and 3rd ORI is mainly enriched in the middle and lower of expanding system tract,and near the maximum flooding surface,respectively.The total organic carbon content(TOC)varied widely and frequently in periphery of deep depression due to dilution of organic matter by turbidity flow,and had a slight change in the center of the deepest sag.The linear relationship between TOC and paleoredox coefficient of V/Cr and Pr/Ph is observed in 5th and3 rd ORI.TOC in the 3rd ORI shows a positive correlation well with the paleoproductivity coefficient of Cu and Ni contents.The evidence indicates that stratified water column with high salinity and anoxic conditions under arid climate enhanced OM storage in 5th ORI,and the conjunction of high productivity following phytoplankton bloom coupled with oxygen-depleted bottom water in the relatively deep basin are favorable for OM preservation and accumulation in 3rd ORI.
The shales in He-3Member of Paleogene Hetaoyuan Formation in the Biyang Depression mainly consists of hydrocarbon source rocks,and can be divided into five organic-matter-rich intervals(ORIs),where organic matter(OM)is distributed regularly in the sequence stratigraphic framework.The present work addresses the distribution of major elements,trace elements and biomarker parameters of shales from5 th and 3rd ORIs for discussion of the relationships between the enrichment of organic matter and the changes of climate,salinity,redox condition,productivity,and identification of the mechanism of OM accumulation in the sequence stratigraphic framework.The results show that OM of 5th and 3rd ORI is mainly enriched in the middle and lower of expanding system tract,and near the maximum flooding surface,respectively.The total organic carbon content(TOC)varied widely and frequently in periphery of deep depression due to dilution of organic matter by turbidity flow,and had a slight change in the center of the deepest sag.The linear relationship between TOC and paleoredox coefficient of V/Cr and Pr/Ph is observed in 5th and3 rd ORI.TOC in the 3rd ORI shows a positive correlation well with the paleoproductivity coefficient of Cu and Ni contents.The evidence indicates that stratified water column with high salinity and anoxic conditions under arid climate enhanced OM storage in 5th ORI,and the conjunction of high productivity following phytoplankton bloom coupled with oxygen-depleted bottom water in the relatively deep basin are favorable for OM preservation and accumulation in 3rd ORI.
引文
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[8]李吉君,史颖琳,章新文,等.页岩油富集可采主控因素分析:以泌阳凹陷为例[J].地球科学:中国地质大学学报,2014,39(7):848-857.
[9]王敏,陈祥,严永新,等.南襄盆地泌阳凹陷陆相页岩油地质特征与评价[J].古地理学报,2013,15(5):663-671.
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[11]吕奇奇,罗顺社,罗家群,等.泌阳凹陷南部陡坡带核桃园组岩相古地理及时空演化[J].中国地质,2012,39(1):77-85.
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[14]孙镇城,杨藩,张枝焕,等.中国新生代咸化湖泊沉积环境与油气生成[M].北京:石油工业出版社,1997.
[15]Adams T D,Haynes J R,Walker C T.Boron in Holocene illites of the Dovey estuary,Wales,and its relationship to palaeosalinity in cyclothems[J].Sedimentology,1965,4(3):189-195.
[16]陈亮,刘春莲,庄畅,等.三水盆地古近系下部湖相沉积的稀土元素地球化学特征及其古气候意义[J].沉积学报,2009,27(6):1155-1162.
[17]Volkman J K.A review of sterol markers for marine and terrigenous organic matter[J].Organic Geochemistry,1986,9(2):83-99.
[18]Volkman J K,Barrett S M,Blackburn S I,et al.Microalgal biomarkers:A review of recent research developments[J].Organic Geochemistry,1998,29(5):1163-1179.
[19]胡玮,卢宗盛,喻鹏.陆相盆地古生产力研究现状[J].地质科技情报,2010,29(6):15-20.
[20]Mclennan S M,Taylor S R.The continental crust:Its composition and evolution[M].Oxford:Blackwell Scientific Publications,1985:1-301.
[21]刘建锋,朱筱敏,王敏,等.泌阳凹陷核桃园组三段上亚段滑塌浊积扇沉积特征[J].石油与天然气地质,2011,32(5):743-745.
[2]Wignall P B,Maynard J R.The sequence stratigraphy of transgressive black shales[C]∥Katz B J,Pratt L M.Source rocks in a sequence stratigraphic framework.Oklahoma:AAPG Bulletin,1993:35-47.
[3]Passey Q R,Bohacs K M,Esch W L,et al.From oil-prone source rock to gas-producing shale reservoir-geologic and petrophysical characterization of unconventional shale-gas reservoirs[R].[S.l.]:Society of Petroleum Engineers,Report131350,2010:1-29.
[4]Frank M C,Tyson R V.Parasequence-scale organic facies variations through an Early Carboniferous Yoredale cyclothem,Middle Limestone Group,Scremerston,Northumberland[J].Journal of the Geological Society,1995,152(1):41-50.
[5]刘震,吴因业.层序地层框架与油气勘探[M].北京:石油工业出版社,1999.
[6]董田,何生,林社卿.泌阳凹陷核桃园组烃源岩有机地化特征及热演化成熟史[J].石油实验地质,2013,35(2):187-194.
[7]李志明,张隽,余晓露,等.南襄盆地泌阳凹陷烃源岩成熟度厘定及其意义[J].石油实验地质,2013,35(1):76-80.
[8]李吉君,史颖琳,章新文,等.页岩油富集可采主控因素分析:以泌阳凹陷为例[J].地球科学:中国地质大学学报,2014,39(7):848-857.
[9]王敏,陈祥,严永新,等.南襄盆地泌阳凹陷陆相页岩油地质特征与评价[J].古地理学报,2013,15(5):663-671.
[10]张文昭.泌阳凹陷古近系核桃园组三段页岩油储层特征及评价要素[D].北京:中国地质大学,2014.
[11]吕奇奇,罗顺社,罗家群,等.泌阳凹陷南部陡坡带核桃园组岩相古地理及时空演化[J].中国地质,2012,39(1):77-85.
[12]Jones B,Manning D A.Comparison of geochemical indices used for the interpretation of palaeoredox conditions in ancient mudstones[J].Chemical Geology,1994,111(1):111-129.
[13]Didyk B M,Simoneit B,Brassell S T,et al.Organic geochemical indicators of palaeoenvironmental conditions of sedimentation[J].Nature,1978,272:216-222.
[14]孙镇城,杨藩,张枝焕,等.中国新生代咸化湖泊沉积环境与油气生成[M].北京:石油工业出版社,1997.
[15]Adams T D,Haynes J R,Walker C T.Boron in Holocene illites of the Dovey estuary,Wales,and its relationship to palaeosalinity in cyclothems[J].Sedimentology,1965,4(3):189-195.
[16]陈亮,刘春莲,庄畅,等.三水盆地古近系下部湖相沉积的稀土元素地球化学特征及其古气候意义[J].沉积学报,2009,27(6):1155-1162.
[17]Volkman J K.A review of sterol markers for marine and terrigenous organic matter[J].Organic Geochemistry,1986,9(2):83-99.
[18]Volkman J K,Barrett S M,Blackburn S I,et al.Microalgal biomarkers:A review of recent research developments[J].Organic Geochemistry,1998,29(5):1163-1179.
[19]胡玮,卢宗盛,喻鹏.陆相盆地古生产力研究现状[J].地质科技情报,2010,29(6):15-20.
[20]Mclennan S M,Taylor S R.The continental crust:Its composition and evolution[M].Oxford:Blackwell Scientific Publications,1985:1-301.
[21]刘建锋,朱筱敏,王敏,等.泌阳凹陷核桃园组三段上亚段滑塌浊积扇沉积特征[J].石油与天然气地质,2011,32(5):743-745.