海拉尔盆地乌尔逊—贝尔凹陷白垩系原油地球化学特征及油源对比

对海拉尔盆地乌尔逊凹陷和贝尔凹陷共21个原油和油砂样品进行GC、GC-MS和非烃含氮化合物测试分析,根据饱和烃、轻烃和甾萜类生物标志化合物的分析资料,全面剖析了海拉尔盆地乌尔逊-贝尔凹陷白垩系原油的地球化学特征,并通过油源对比确定了其主力烃源层。研究结果表明,海拉尔盆地贝尔凹陷和乌尔逊凹陷原油存在2种成因类型:第一类油饱和烃C₁₇—C₂₃具正构烷烃优势,呈单峰型分布,Pr/Ph>1(1~2.88),C₂₇—C₂₉甾烷呈"V"型分布,伽马蜡烷含量较低,表征淡水湖相沉积环境;第二类油具有饱和烃低碳正构烷烃优势,Pr/Ph<1,孕甾烷、C₂₇重排甾烷含量较低,伽马蜡烷不发育,表征煤系地层原油。油源对比揭示,原油来自2套不同沉积环境的源岩,展示了海拉尔盆地良好的烃源条件。 

GEOCHEMICAL CHARACTERISTICS OF THE CRETACEOUS OIL AND CORRELATION OF OIL TO SOURCE ROCK IN WUERXUN AND BEIER DEPRESSIONS,THE HAILAER BASIN

Based on the GC,GC-MS and nonhydrocarbon nitric chemical compound analytical data of 21 samples of crude oil and hydrocarbon-bearing rocks,the geochemical characteristics of the Cretaceous oil in Wuerxun and Beier depressions in Hailaer Basin were studied,and the main source rock for the oil was determined by oil-source rock correlation.The studied results reveal that there are two kinds of crude oil in Wuerxun and Beier depressions.One kind shows a dominance of n-alkanes in C₁₇-C₂₃ and distribution in unimodality.Its Pr/Ph is higher than 1(1～2.88).The"V"shaped distribution of C₂₇-C₂₉ steranes and low gammacerane indicate a fresh water lacustrine source rock.The other one shows a dominance of n-alkanes in light hydrocarbons and low C₂₇ sterane.Its Pr/Ph is less than 1 and it lacks gammacerane.This kind of oil mostly stemmed from the coal measure strata.According to the results of oil-source rock correlation,the crude oils in Wuerxun and Beier depressions stemmed from two kinds of depositional setting.It indicates that there are good conditions of source rock in Hailaer Basin.