塔河油田溶洞充填物的元素地球化学特征及环境意义  

Element Geochemistry Characteristics of Karstic Cave Deposit in Tahe Oilfield and Its Environmental Significance

作　　者：刘显凤[1,2,3] 蔡忠贤[2,3] 

机构地区：[1]中国地质大学研究生院,武汉430074 [2]中国地质大学资源学院,武汉430074 [3]中国地质大学构造与油气资源教育部重点实验室,武汉430074

出　　处：《地质科技情报》2009年第3期53-57,共5页Geological Science and Technology Information

基　　金：国家重点基础研究发展规划"973"项目(2005CB422105)

摘　　要：塔河油田位于塔里木盆地塔北隆起阿克库勒凸起的西南部,加里东-海西期强烈抬升导致的大气淡水岩溶作用、早石炭世发生的广泛海侵以及二叠纪大规模的火山活动,对奥陶系岩溶储层产生了不同程度的改造。对塔河地区的地质演化特征以及塔河油田地区溶洞砂泥质充填物镓、铷、锶、钡等微量元素和稀土元素的研究表明,大部分样品表现出淡水岩溶特征,仅T615井等4口井的溶洞充填物却表现出海水成因特征,充填物的元素地球化学特征表现出与早期大气淡水岩溶作用的叠加效应;此外,还有少量样品具有能反映热液作用特征的Eu正异常,说明该区碳酸盐岩地层也受热水溶蚀作用的影响。通过溶洞方解石和溶洞方解石胶结物碳、氧同位素值分布特征的分析也证实了塔河地区除了发育大气淡水岩溶作用外,还存在海水-淡水混合水溶蚀作用和热液溶蚀作用。Tahe Oilfield lies in southwest margin of Akekur Salient in north Tarim basin. Meteoric water karstification because of intensive uplift during Caledonian-Hercynian period, extensive transgression in early Carboniferous and large scale magma and volcano events in Permian would influence the Ordovician carbonate formation. Based on the features of geology evolvement, a study is made of arenaceous and pelit- ic karstic cave deposit on its trace elements such as Ga, Rb, etc, and REE characteristics in the main Tahe Oilfield. The results indicate that most samples show characteristic of fresh water corrosion, while sam- ples of the four wells such as T615 reveal the influence of seawater. It can be inferred that the seawater-fresh water mixing corrosion is not intense in this area, and that the characteristics of element geochemis- try of karstic filling indicate the overlay on the earlier fresh water corrosion. The analysis refelcts that positive europium anomaly of some samples may be relative to the hydrothermal fluids in Permian. Also the analysis of the carbon and oxygen isotopes suggests the occurrence of freshwater-seawater mixed corrosion and magma hydrothermal fluid corrosion in the oilfield except for fresh water corrosion.

关 键 词：塔河油田 砂泥质充填物 岩溶方解石 微量元素 稀土元素 碳氧同位素 岩溶环境 

分 类 号：P595[天文地球—地球化学]