摘要
查明油页岩的形成背景和高品质油页岩形成机制是开展油页岩原位改造的基础工作.利用有机碳、主微量元素、稀土元素、生物标志物等地球化学方法,对茂名盆地油柑窝组油页岩的沉积环境进行恢复并探讨了有机质聚集机制.结果表明,茂名盆地油柑窝组全段油页岩均富有机质,底部为薄层碳质页岩、砂岩和褐煤层段.Mo含量、Ba/Al、Ba_(bio)和生物标志物特征表明油柑窝组具有很高的初级生产力,油柑窝组存在间断性的“藻类勃发”现象;V/(V+Ni)、Ce_(anom)、Th/U、草莓体黄铁矿颗粒大小和Pr/nC_(17)-Ph/nC_(18)交汇图表明了沉积水体处于缺氧还原环境;Sr/Cu、Rb/Sr和气候指数C指示油柑窝组为温暖湿润的古气候条件;Sr/Ba、Ba/Ga、Ca/(Fe+Ca)、Al_(2)O_(3)/MgO以及伽马蜡烷等特征反映了古湖泊水体为淡水;Zr/Al、Rb/K和MnO含量指示为半深湖-深湖沉积环境.通过各指标与TOC含量之间的相关性分析,认为温暖湿润气候和淡水环境为藻类的繁盛提供了良好的环境,具备很高的初级生产力,直接影响了油页岩的品质和发育特征,具有丰富有机质来源的表层生产力是油页岩形成的首要条件,缺氧还原的半深湖-深湖环境有利于沉积有机质堆积和保存,是有机质聚集的促进因素.综合各因素,提出了茂名盆地油柑窝组优质油页岩有机质的聚集模式.
To identify the formation background of oil shale and the enrichment mechanism of high-quality intervals are the fundamental works for in-situ upgrading of oil shale reservoir.In this paper,geochemical methods,e.g.,TOC,major and trace element,rare earth element and biomarkers,were carried out to restore paleosedimentary environment as well as discuss organic matter accumulation mechanism.The results suggest that oil shale within the entire interval of Youganwo Formation is rich in organic matter,and the bottom is composed of thin carbonaceous shale,sandstone and lignite.Mo content,Ba/Al,Ba_(bio) and biomarkers all reflect that Youganwo Formation has high primary productivity,with intermittent“algal bloom”phenomenon.V/(V+Ni),Ce_(anom),Th/U,pyrite framboids and Pr/nC_(17)-Ph/nC_(18) crossplot indicate that Youganwo Formation was anoxic environment.Sr/Cu,Rb/Sr and climate index C identify that the climate of Youganwo Formation was warm and humid.Sr/Ba,Ba/Ga,Ca/(Fe+Ca),Al_(2)O_(3)/MgO and gammacerane feature suggest that water of ancient lake is fresh.The ancient lake of Youganwo Formation was semi-deep to deep,proved by Zr/Al,Rb/K and MnO content.Through the correlations between paleoenvironmental parameters with TOC content,it is deemed that the warm and humid climate and freshwater environment can provide good conditions for the flourishing of algae,forming high quality productivity,and therefore it determines the quality and development characteristics of Youganwo Formation oil shale.High primary productivity with abundant organic matter sources is the main condition for oil shale formation,and anoxic semi-deep to deep lake environment,as a promoting factor,is conducive to organic matter accumulation and preservation.To sum up,in this paper it proposes the accumulation model of organic matter in high-quality oil shale of Youganwo Formation in the Maoming Basin.
作者
曹涛涛
刘虎
肖娟宜
潘安阳
邓模
Cao Taotao;Liu Hu;Xiao Juanyi;Pan Anyang;Deng Mo(School of Earth Sciences and Spatial Information Engineering,Hunan University of Science and Technology,Xiangtan 411201,China;Sichuan Key Laboratory of Shale Gas Evaluation and Exploration,Chengdu 610091,China;Sichuan Institute of Geological Survey,Chengdu 610072,China;Wuxi Research Institute of Petroleum Geology,Petroleum Exploration&Production Research Institute,SINOPEC,Wuxi 214126,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2024年第4期1367-1384,共18页
Earth Science
基金
国家自然科学基金项目(Nos.41802163,42002136)
湖南省自然科学基金项目(Nos.2021JJ30240,2018JJ3152)
湖南省教育厅优秀青年基金项目(No.21B048)
页岩气资源利用湖南省重点实验室开放基金项目(No.E22218)。
关键词
油页岩
古环境
地球化学
有机质聚集
油柑窝组
茂名盆地
石油地质学
oil shale
paleo environment
geochemistry
organic matter accumulation
Youganwo Formation
Maoming basin
petroleum geology
