塔里木盆地东北地区下寒武统烃源岩发育模式——以塔东1井为例
Development model of the Lower Cambrian source rocks in northeastern Tarim basin:A case study from Well Tadong1
张春宇 1管树巍 2谢晓军 1吴林 3任荣 2熊连桥1
作者信息
- 1. 中海油研究总院有限责任公司 北京 100028
- 2. 中国石油勘探开发研究院 北京 100083
- 3. 中国地质科学院地质力学研究所 北京 100081
- 折叠
摘要
塔里木盆地早寒武世发育了一套富有机质黑色泥岩,是盆内重要烃源岩之一.目前对这套烃源岩在塔西北地区的研究较多,然而塔东北区研究程度相对薄弱.通过对塔东1井下寒武统泥岩进行矿物学和地球化学特征实验研究,基于实验结果分析了寒武系烃源岩形成主控因素,建立了这套烃源岩发育模式,并对比了其与塔里木盆地其他区烃源岩的差异.塔东1井下寒武统发育硅质泥岩和钙质泥岩;Al2O3、TiO2、Zr及总稀土元素含量较低,Lan/Ybn显示重稀土富集特征,表明受陆源碎屑影响较小;Cd/Mo与Co × Mn及TOC与地化图解显示塔东北地区广泛受上升洋流作用影响;样品整体TOC较高,均值达到3.52％,结合P2O5及生物成因硅含量特征,表明下寒武统泥岩具有较高有机质生产力,其中下部生产力极高;U、V及Mo远高于后太古界澳大利亚页岩(PAAS),有机碳与磷的比值(Corg∶P)均值为242,表明该区早寒武世水体处于还原环境.结合区域构造演化,认为塔东北区下寒武统烃源岩受古地貌、海平面、上升洋流等多方面因素影响;塔里木盆地不同地区下寒武统烃源岩主要在沉积相带及受热液影响这两方面存在差异.
Abstract
The Lower Cambrian consists of organic-rich mudstone,which is one of the major source rocks in the Tarim basin.At present,the source rocks in northeastern Tarim basin are poorly studied compared with those in northwestern Tarim basin.Based on the experimental study of mineralogy and geochemical characteristics of Lower Cambrian mudstone in Well Tadong1,the main factors controlling the formation of Cambrian source rocks are analyzed based on the experimental results,the development model of the source rocks is established,and its differences with other source rocks in Tarim basin are compared.The results showed that,the Lower Cambrian in Well Tadong1 consists of siliceous and calcareous mudstone.The concentrations of Al2O3,TiO2,Zr and total rare earth element are low,and Lan/Ybn shows heavy rare earth elements enrichment,indicating that they are less affected by terrestrial debris.Crossplots of Cd/Mo-Co*Mn and TOC-geochemical diagram suggest that the northeastern Tarim basin is affected by widespread upwelling The high TOC content TOC,averaging at 3.52％,as well as the concentration of P2O5 and Sibio,indicating that the Lower Cambrian mudstone has high palaeoproductivity,with extremely high palaeoproductivity in the lower part.The trace mental enrichment of U,V,Mo are much higher than those in post Archean Australian shale(PAAS),and the average ratio of organic carbon to phosphorus(Corg:P)is 242,suggesting anoxic bottom water during the Early Cambrian.In combination with regional tectonic evolution,it is believed that the Lower Cambrian source rocks in the northeastern Tarim basin are influenced by various factors such as palaeotopography,eustacy,and upwelling.The Lower Cambrian source rocks in different areas of the Tarim basin are mainly different in sedimentary facies belt and hydrothermal influence.
关键词
塔里木盆地/下寒武统/烃源岩/地化特征/发育模式/塔东1井Key words
Tarim basin/Lower Cambrian/source rocks/geochemical characteristics/development model/Well Tadong1引用本文复制引用
出版年
2024
NETL
NSTL
万方数据