准噶尔盆地玛页1井风城组生物标志化合物及其对古环境和生烃生物的指示  

Lipid biomarkers of the Fengcheng Formation from the Maye 1 borehole in the Junggar Basin and its indication of paleoenvironment and hydrocarbon-generating organisms

作　　者：谢媛 张华[1] XIE Yuan;ZHANG Hua(Key Laboratory of Palaeobiology and Petroleum Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing 210008,Jiangsu,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院南京地质古生物研究所古生物学与油气地层应用重点实验室,江苏南京210008 [2]中国科学院大学,北京100049

出　　处：《地球化学》2024年第3期370-385,共16页Geochimica

基　　金：中国科学院战略性先导科技专项(B类)(XDB26000000);中国石油新疆油田分公司技术服务项目(2020-C4011)联合资助。

摘　　要：新疆准噶尔盆地西北缘玛湖凹陷风城组是盆地内最重要的烃源岩之一,目前发现的周缘油田大多与这一套烃源岩有关。然而,玛湖凹陷风城组烃源岩的有机质大多被改造成无定形体,尤其是大量藻类原始生物结构都已被破坏而无法鉴定,导致其生烃生物尚不明确。生物标志化合物可以为探索风城组烃源岩生烃生物及古环境背景提供一定的指示信息。本研究选取玛湖凹陷西北缘第一口对风城组全取心的玛页1井岩心利用气相色谱–质谱(GC-MS)技术,通过对正构烷烃、类异戊二烯烃、藿烷及甾烷等进行分析,探索风城组沉积时期的生物组成及古环境特征。结果表明,玛页1井风城组烃源岩碳优势指数(CPI)与奇偶优势(OEP)均在1附近,不具有明显奇偶优势;Ts/(Ts+Tm)、C_(29)20S/(20S+20R)甾烷及重排甾烷/规则甾烷等指示的成熟度略有不同,但总体处于低成熟–成熟阶段;遭受了低–中等程度的生物降解,各层段生物降解程度差异不明显;姥鲛烷/植烷(Pr/Ph)值为0.44~0.82,呈现出明显的植烷优势;高伽马蜡烷丰度和Pr/n-C_(17)与Ph/n-C_(18)的关系,指示风城组沉积于具有明显水体分层且盐度较高的还原–强还原环境中。正构烷烃的碳数分布广,呈低碳数占优势的单峰型;三环萜烷丰富,藿烷以C_(29)和C_(30)为主,升藿烷呈C_(31)>C_(32)>C_(33)>C_(34)>C_(35)正常降序分布;C27~C_(29)规则甾烷呈现C_(28)和C_(29)占优势的特征;甾烷含量普遍高于藿烷含量;β-胡萝卜烷含量高,2-甲基藿烷指数低,说明生烃生物以耐盐藻类为主。The Fengcheng Formation in the Mahu Sag of the Junggar Basin,Northwest Xinjiang,is one of the most important source rocks in the basin,and most of the surrounding oilfields are related to this set of source rocks.However,most of the organic matter in the Fengcheng Formation in the Mahu Sag has been degraded into amorphous forms,the original biological structures of algae in particular have been destroyed and cannot be identified,so the specific hydrocarbon-generating organisms are still not clear.Biomarker compounds can provide information on the biological and paleoenvironmental background of the source rocks in the Fengcheng Formation.To explore the biological assemblage and the palaeoenvironmental features of the Fengcheng Formation,samples of the Fengcheng Formation from the Maye 1 borehole were analyzed for the saturated hydrocarbons including normal alkanes,isoprenoids,hopanes,and steranes by using gas chromatography-mass spectrometry(GC-MS).Both carbon preference index(CPI)and odd-even predominance(OEP)values are around 1,showing that the source rocks do not have odd-even carbon dominance.The maturity parameters from biomarkers,especially the ratios of Ts/(Ts+Tm)and C_(29)20S/(20S+20R)steranes suggest that the maturity of organic matter is in the low maturity-maturity stage.The source rocks of the Fengcheng Formation experienced low to medium biodegradation,and there is no noticeable difference in biodegradation degree among the three members of the Fengcheng Formation.The pristane/phytane ratios range from 0.44 to 0.82,and the substantial phytane prevalence indicates that the Fengcheng source rocks were deposited in a reducing environment.The high gammacerane index and the relationship between Pr/n-C_(17) and Ph/n-C_(18) indicate that the Fengcheng Formation was deposited in a stratified water environment.The high contents of tricyclic terpanes and low contents of Ts and 2-methylhopane also are important features of the Fengcheng Formation.Meanwhile,the C_(29) and C_(30) hopanes are usually more abundant

关 键 词：玛湖凹陷 玛页1井 风城组 饱和烃 生物标志化合物 

分 类 号：P593[天文地球—地球化学]