二连盆地赛汉塔拉凹陷腾二段低熟油地球化学特征和油源对比

赛汉塔拉凹陷位于二连盆地腾格尔坳陷西部,是二连盆地低熟油分布区.采用有机地球化学和生物标志物分析方法,对赛汉塔拉凹陷下白垩统腾二段低熟原油和油砂样品进行了地球化学特征和油源对比研究.赛汉塔拉凹陷腾二段低熟油具有饱和烃含量相对较低、非烃和沥青质含量相对较高的族组成特征,正构烷烃分布以前峰型为主,主峰碳为C21或C23,P...

Geochemical Characteristics and Source Correlation of Low-mature Oil from the Tengeer Formation(2nd Member)in the Saihantala Sag,Erlian Basin

The Saihantala Sag is located in the western Tengeer depression of Erlian Basin,and contains low-mature oil in the Erlian Basin.The geochemical characteristics and oil source correlation of the low-mature crude oil and oil sandstone samples from the Lower Cretaceous Tengeer Formation(2nd member)in the Saihantala Sag were studied,by using organic geochemical and biomarker analyses.The low-mature oil from the Tengeer Formation(2nd member)is characterized by having relatively low content of saturated hydrocarbon,and relatively high content of non-hydrocarbon and asphaltene.The distribution of n-alkanes is of pre-peak type,and the main peak carbon is C₂₁,C₂₃.The Pr/Ph is low(0.29 to 0.58),Pr/nC₁₇is relatively low(0.29 to 0.59),Ph/nC₁₈is relatively high(0.57 to 1.37),and C₂₉20S/(20S+20R)of sterane is 0.27 to 0.40,C₂₉ββ/(αα+ββ)of sterane is 0.29 to 0.39,the gammacerane index is mainly 0.31 to 1.34,and the tricyclic terpane content is low,which reflects that the sedimentary environment of crude oil is a brackish-saline reducing one with mainly algae source input.According to the study of oil source correlation,there are two sources of the low-mature oils from the Tengeer Formation(2nd member)in the Saihantala Sag:(1)from the underlying Tengeer Formation(1st member)source rock and hydrocarbon generation at the early mature stage in salt-water environment;(2)from the self-generation and self-storage of the lowly-mature Tengeer Formation(2nd member)source rock in the depression center.