CAJ | 학술논문

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。
대시체목분지서부각유전적151개원유진행료분자지구화학분석，병선취가마사완/C30곽완、승곽완지수、치완C27/C29화삼배첩완/C30Hop사개삼수작위변량진행SAS취류분석。결합상규이유산점도법，시서원유가이분위3개유족7개아족：유족Ⅰ이강수체분층、강환원배경위특정，주요분포우서단적칠개천、홍류천지구，해유족가이분위량개아족，유아족②상비우유아족①구유경고적치완 C27/C29비치；유족Ⅱ주요분포우사자구、화토구、약진화남익산유천자지구，재칠개천、홍류천등지구야유분포，이상대교강적수체분층、환원배경위특정；유족Ⅲ주요분포우동(남)부적절극리극、오남、록초탄、함수천、약서화약진Ⅱ호등지구，이수체분층변차、교환원배경위특정，해유족가이분위3개아족，기중유아족⑤칙구유이상저적삼배첩완/C30Hop 비치，유아족⑥구유이상고적치완 C27/C29비치，유아족⑦칙구유이상고적삼배첩완/C30Hop 비치。유족공간분포특정수하간시구조원암유궤상재공간상적변화제약，하간시구조원암발육시기，자서향동지층침적속솔증대，수체적분층변차、환원성강저，도치륙원수입적증가이급유궤질보존조건변차。
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 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.