柴达木盆地西部油族划分及成因研究  

The oil families and their genesis in the western Qaidam Basin

作　　者：王强[1] 王飞宇[1,2] 陈琰[3] 冯伟平[1] 袁莉[3] 

机构地区：[1]中国石油大学地球科学学院,北京102249 [2]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [3]中国石油青海油田公司,甘肃敦煌736202

出　　处：《地球化学》2014年第2期122-130,共9页Geochimica

基　　金：国家油气专项(2011ZX05007-001);中石油柴达木盆地专项(2012-ZG-001)

摘　　要：对柴达木盆地西部各油田的151个原油进行了分子地球化学分析,并选取伽马蜡烷/C30藿烷、升藿烷指数、甾烷C27/C29和三环萜烷/C30Hop四个参数作为变量进行SAS聚类分析。结合常规二维散点图法,柴西原油可以分为3个油族7个亚族:油族Ⅰ以强水体分层、强还原环境为特征,主要分布于西端的七个泉、红柳泉地区,该油族可以分为两个亚族,油亚族②相比于油亚族①具有更高的甾烷C27/C29比值;油族Ⅱ主要分布于狮子沟、花土沟、跃进和南翼山油泉子地区,在七个泉、红柳泉等地区也有分布,以相对较强的水体分层、还原环境为特征;油族Ⅲ主要分布于东(南)部的切克里克、乌南、绿草滩、咸水泉、跃西和跃进Ⅱ号等地区,以水体分层变差、较还原环境为特征,该油族可以分为3个亚族,其中油亚族⑤则具有异常低的三环萜烷/C30Hop比值,油亚族⑥具有异常高的甾烷C27/C29比值,油亚族⑦则具有异常高的三环萜烷/C30Hop比值。油族空间分布特征受下干柴沟组源岩有机相在空间上的变化制约,下干柴沟组源岩发育时期,自西向东地层沉积速率增大,水体的分层变差、还原性降低,导致陆源输入的增加以及有机质保存条件变差。Based on the molecular geochemical analysis of 151 crude oils in the western Qaidam basin, a SAS （Statistical Analysis System） cluster analysis was carried out by selecting four variables （i.e. ratios of gammacerane/C30hopane, sterane C27/C29, and tricyclic terpanes/C30hopane, and homohopane index. Combined with 2-D scatter plot, the oils in the western Qaidam basin can be divided into three oil families and seven oil subfamilies. Oil-family I, including two oil subfamilies, is characterized by strong water column stratification and strong reducing environment, and mainly distributes in Qigequan-Hongliuquan. Oil subfamily②has higher ratios of sterane C27/C29 than Oil-subfamily ①. Oil-familyⅡ is characterized by relatively strong water column stratification and reducing environment, mainly distributes in Shizigou , Huatugou, Yuejin, Youquanzi, Nanyishan and Youquanzi, and small amount appears in Qigequan-Hongliuquan; Oil-family Ⅲ, including three oil subfamilies, is characterized by relatively weak water column stratification and reducing environment, mainly distributes in Qiekelike, Wuan, Lvcaotan, Xianshuiquan, Yuexi, Yuejin-Ⅱ, in which the oil subfamily ⑤ has unusually low tricyclic terpanes/C30Hop, oil subfamily⑥has unusually high sterane C27/C29, and oil subfamily⑦has unusually high tricyclic terpanes/C30Hop. The spatial distribution of oil families is controlled by the spatial＆amp;nbsp;variation in organic facies of source rock. For example, during the deposition of E3 Formation, the depositional environment displays a change trend of increasing sedimentation rate, worse water column stratification and decreasing reducibility from west to east, which lead to the increasing terrestrial input and deteriorated preservation conditions of organic matter from west to east.

关 键 词：油族划分 沉积有机相 地球化学 生物标志物 柴达木盆地 

分 类 号：P593[天文地球—地球化学]