柴达木盆地西南缘乌南油田原油地球化学特征  

Geochemical Characteristics of Crude Oils from Wunan Oilfield,Qaidam Basin

作　　者：张明峰[1] 妥进才[1] 李中平[1] 刘立 郭力军 

机构地区：[1]中国科学院地质与地球物理研究所,中国科学院油气资源研究重点实验室,甘肃兰州730000 [2]甘肃省环境科学设计研究院,甘肃兰州730000 [3]中国石油青海油田分公司勘探开发研究院,甘肃敦煌736202

出　　处：《天然气地球科学》2011年第5期840-847,共8页Natural Gas Geoscience

基　　金：国家自然科学基金(编号:41103022);中科院西部之光人才培养西部博士项目(编号:Y134MF1ZMF),中国科学院油气资源研究重点实验室开放基金(编号:KFJJ2010-08)联合资助

摘　　要：通过对柴达木盆地西南缘乌南油田原油样品饱和烃、芳烃生物标志化合物和单体烃碳同位素的系统分析,阐明了它们的地球化学特征。研究结果表明,样品中正构烷烃系列碳数分布具有双重性模式,Pr/Ph<0.5,呈强植烷优势;具有相对较高含量的三环萜烷和伽马蜡烷,藿烷C35/C34值基本上≤1;芳烃组分主要以萘系列、菲系列为主,三芳甾烷系列化合物含量较高,指示了乌南原油形成于半咸水—咸水湖相较强还原沉积环境,母质来源主要为低等水生生物,藿烷和甾烷成熟度参数反映其主要为低熟原油。原油单体烃碳同位素分布曲线模式整体上较为水平,高碳数略有增高的趋势,也表明了原油以水生生物和细菌为主的偏腐泥型有机质生源特征。By measuring the stable carbon isotopes of satisfied hydrocarbon, aromatics and single hydrocarbons in crude oil collected from the Wunan oilfield in southwest margin of Qaidam basin, we discuss the geochemical features of the crude oil. The results indicate that the n-alkanes present a bimodal distribution pattern （i. e. , odd-to-even and even-to-odd carbon predominance）, associated with low ratios of Pr/Ph （〈 0.5） and C35-Hopane/C34-Hopane （〈1. 0） ,high abundance of tricyclic-terpanes and gammacerane,and occurrence of hopane （C35）. The aromatic hydrocarbons compounds were mainly composed of naphthalene and phenanthrene, and a relatively high amount of triaromatic steroid compounds occurs. These results con- firm that the crude oils in the Wunan oilfield were formed in a mild-salty to salty redution depositional environment, and the parent input matter mainly derived from the lower aquatic organisms. The biomarker parameters of thermal maturity （i. e. hopanes and steranes） suggest a low thermal maturity of the crude oil. Carbon isotope of crude oils （31aC bulk） was relatively heavy,in contrast that the carbon isotope values of single molecule hydrocarbons （~13C n-alkanes） remain unchanged with exception of carbon isotope increase in high carbon number,which also support that the source matter of crude oils were derived from aquatic organisms,as well as the sapropelic organic matter.

关 键 词：柴达木盆地 乌南油田 原油 生物标志化合物 单体烃碳同位素 

分 类 号：TE122.113[石油与天然气工程—油气勘探]