乍得Bongor强反转裂谷盆地高酸值原油成因  

Origin of high acidity oils in the intensively inversed rift basin,Bongor Basin

作　　者：程顶胜[1] 窦立荣 肖坤叶[1] 万仑坤[1] 刘宝全 

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国石油天然气勘探开发公司,北京100034 [3]大庆方兴油田开发有限责任公司,大庆163000

出　　处：《岩石学报》2014年第3期789-800,共12页Acta Petrologica Sinica

基　　金：国家油气重大专项项目(2011ZX0502901);中国石油天然气集团公司科技专项项目(2013D0902)联合资助

摘　　要：乍得Bongor盆地是受中非剪切带影响发育起来的中、新生代陆内强反转裂谷盆地,反转和走滑构造是盆地最显著的构造特征。所发现的原油主要为中质油(重度为20°～34°API),其次为重质油(重度小于20°API),普遍高含沥青质、高含蜡、高酸值、低含硫。为了探讨高酸值原油的成因,作者选择了该盆地15个不同酸值的原油样品,尝试应用高分辨率质谱分析原油有机酸的组成。分析结果表明,高酸值原油的有机酸主要由环烷酸组成;环烷酸碳原子数分布范围较宽,且以一环、二环、三环环烷酸为主。生物降解作用是形成高酸值原油的主要原因,而构造反转造成盆地抬升,则加速了生物降解作用的发生。Bongor Basin is a Meso-Cenozoic interior intensively inversed rift basin under the influence of the Central African Shear Zone （CASZ）, which is essentially characterized by inversion and strike-slip structures. Crude oils produced from the basin display unusual high total acid number values （TAN, up to 8.3mgKOH/g oil） with high wax content and asphaltene. In order to probe the formation mechanism of high acid a total of 15 oils with different TANs were characterized for organic acids composition by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Results indicated that the organic acids are mainly naphthenic acid, dominating with mono-cyclic, bi-cyclic, tri-cyclic naphthenic acids. The formation of high TAN oils was attributed to biodegradation which has been promoted by the strong uplift and inversion stage in Late Cretaceous.

关 键 词：高酸值原油 高分辨率质谱 生物降解作用 反转裂谷盆地 Bongor盆地 乍得 

分 类 号：P542[天文地球—构造地质学] P618.13[天文地球—地质学]