正构烷烃单体碳同位素组成差异分析——以塔河油田奥陶系原油为例  

Analysis of Carbon Isotopic Compositional Differences of Individual n-Alkane:Case study of Ordovician crude oil in Tahe oilfield

作　　者：马冬晨[1,2] 王文军 张婷 李立武 王作栋 钱宇 敖添 符印 王丹[1,2] 贾星亮[1,2] MA DongChen;WANG WenJun;ZHANG Ting;LI LiWu;WANG ZuoDong;QIAN Yu;AO Tian;FU Yin;WANG Dan;JIA XingLiang(Experimental Testing Technology Center of SINOPEC Northwest Oilfield Company,Urumqi 830011,China;SINOPEC Key Laboratory of Fracture-cavity Reservoir Enhanced Oil Recovery,Urumqi 830011,China;Northwest Institute of Eco-environmental Resources,Chinese Academy of Sciences,Gansu Provincial Key Laboratory of Oil and Gas Resources Research,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Sichuan University of Light Chemical Industry,Zigong,Sichuan 643000,China)

机构地区：[1]中国石化西北油田分公司实验检测技术中心,乌鲁木齐830011 [2]中国石化缝洞型油藏提高采收率重点实验室,乌鲁木齐830011 [3]中国科学院西北生态环境资源研究院,甘肃省油气资源勘探与评价重点实验室,兰州730000 [4]中国科学院大学,北京100049 [5]四川轻化工大学,四川自贡643000

出　　处：《沉积学报》2024年第4期1411-1421,共11页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42272187)。

摘　　要：【目的】为明确原油正构烷烃单体碳同位素(δ^(13)C_(alkane))组成差异的成因。【方法】研究分析了塔北地区奥陶系共计17个原油样品δ^(13)C_(alkane)组成特征,结合相关有机地球化学参数,从沉积环境、成熟度和生物降解作用三个方面解释了三类原油δ^(13)C_(alkane)值的变化趋势。【结果与结论】根据物性的差异,可将塔北地区原油分为重质、中质和轻质三类。塔北地区奥陶系原油δ^(13)C_(alkane)值介于-37‰~-31‰,呈现出海相原油的特征,表明原油δ^(13)C_(alkane)组成及分布范围受其形成的沉积环境和母质类型控制;从重质原油到中质原油再到轻质原油,成熟度逐渐增大,导致原油δ^(13)C_(alkane)值正偏;相较于中质原油和轻质原油,重质原油低碳数部分δ^(13)C_(alkane)明显变大,表明生物降解程度是重质原油中、低分子量正构烷烃δ^(13)C14~δ^(13)C19值正偏的主要影响因素。[Objective]To clarify the cause of the different compositions of the individual crude n-alkane carbon iso⁃tope(δ^(13)C_(alkane))in the three categories,[Methods]in this study the composition ofδ^(13)C_(alkane) in 17 Ordovician crude oil samples from the northern Tahe oilfield,combined with relevant organic geochemical parameters,were examined for depositional environment,maturity and biodegradation.[Results and conclusions]The differences in physical properties allows the crude oils in Tahe to be categorized as heavy,medium and light crude oils.Theδ^(13)C_(alkane) value is between 37‰and-31‰.It has the properties of marine crude oil,indicating that the composition and distribution ofδ^(13)C_(alkane) are by the depositional environment and the type of parent material.Maturity gradually increases from heavy to medium to light crude oil,in turn leading to heavierδ^(13)C_(alkane) values,which is significantly higher in the lowcarbonnumber part of the heavy crude oil.The heavy crude oil has been more strongly biodegraded than the medium and light crude oil,indicating that the degree of biodegradation is the main factor affecting the positive bias ofδ^(13)C14 toδ^(13)C19 values of the medium-and low molecular weight n-alkanes in heavy crude oil.

关 键 词：正构烷烃单体碳同位素组成 生物标志化合物 成熟度 生物降解 塔河原油 

分 类 号：P618.13[天文地球—矿床学]