摘要
准噶尔盆地西北缘原油及烃源岩中生物标志物以高丰度的三环萜烷系列为典型特征,其分布样式的差异一直被当作研究本区原油成因类型及油-源对比的典型指标。通过对烃源岩样品的系统地球化学分析,认为本区风城组源岩(P_1f)主要以三环萜烷(C_(20),C_(21),C_(23))呈"上升型"为特征,泥质岩类与碳酸盐岩类相比C24,C25三环萜烷含量较高;下乌尔禾组(P_2w)源岩和佳木河组(P_1j)源岩样品三环萜均呈"下降型"分布特征。通过对源岩镜下进行观察和加水热模拟实验等方法,分别探讨了沉积环境与母质类型、成熟度及排烃作用对三环萜分布样式的影响,认为P_1f和P_2w源岩中三环萜烷的分布主要受控于沉积环境和母质类型的原生差异。P_1f源岩有机质多源于本地沉积的藻类及细菌,沉积环境属于蒸发、还原的咸化湖沉积;P_2w源岩中外来有机质含量相对较多,沉积环境属于淡水还原环境。P_1j源岩整体热演化程度较高,有机质炭化作用强烈;埋藏成熟演化在有机质处于成熟-高熟阶段内对三环萜烷分布样式影响不大,若达到过熟阶段则会造成低碳数三环萜烷(C_(20),C_(21))含量增加;排烃作用对三环萜烷影响相对较小,不改变其分布样式。
Biomarkers extracted from the crude oil and source rock samples obtained from the northwestern margin of Junggar Basin are characterized by high abundance of tricyclic terpanes（ TTs）. The distribution pattern of TTs has been used to distinguish oil families and to conduct oil-source correlations. Comprehensive geochemical analyses of source rock samples reveal that different distribution patterns of TTs correspond to different sets of source rocks,i. e. the Fengcheng Formation（ P1f） features in ＂Going Up＂of C20,C21 and C23 TTs,with higher amounts of C24 and C25 TTs for mudstones in comparison with carbonate rocks;the Lower Wuerhe Formation（ P2w） and the Jiamuhe Formation（ P1j） are characterized by ＂Going Down＂of C20,C21 and C23 TTs. The influences of sedimentary environment,kerogen type,maturity and hydrocarbon expulsion on distribution of TTs were studied through microscopic observation of thin sections and hydrous pyrolysis simulation. We concluded that the TTs distribution patterns of P1f and P2w are mainly controlled by sedimentary environment and kerogen type. The organic matters of the P1f source rocks were mainly derived from autochthonous algae or bacteria and were deposited in an evaporative reducing salt lake,while allochthonous organic matters were relatively abundant in the P2w and were deposited in a semi-reducing fresh lacustrine environment. The P1 j source rocks are currently over-mature and have experienced intense carbonization. Burial thermal evolution has limited impacts on the distri-bution patterns of TTs during mature and high-mature stage,but can result in the increase of low carbon number terpanes during over-mature stage. Hydrocarbon expulsion has limited influences on the TTs distribution pattern.
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2017年第2期311-322,共12页
Oil & Gas Geology
基金
国家科技重大专项(2016ZX05001005)
中石油新疆油田公司课题(2014-C4023)
