三塘湖盆地煤成油地球化学特征

依据生物标志物分布和组成特征，可把三塘湖盆地的原油和油显示分成中生界煤成油和上古生界湖相成因原油两大类，中生界煤成油以塘参1井中侏罗统西山窑组的原油为代表。表现为正构烷烃系列具明显的奇碳优势，Pr/Ph值高（＞4．0），四环萜烷／三环萜烷＞1．0，三环萜烷系列中C19和C20相对丰度高于C21和C23，有C31六环藿烷，无伽玛蜡烷，C29甾烷占绝对优势，该原油源于中生界煤系源岩。上古生界湖相成因原油包括塘参3井，条2井和条3井油显示，其主要特征为正构烷烃系列没有明显的奇偶优势，Pr/Ph值低，三环萜烷／四环萜烷（仅检测到C24一个化合物）＞1．0，且C21和C23三环萜烷的相对丰度高于C19和C29,无C31六环藿烷，有较高含量的伽玛蜡烷和β－胡萝卜烷，C27甾烷丰度较高，它们源于该盆地上古生界湖相烃源岩。

GeochemicalCharacteristics of Coal-derived Oil in Santanghu Basin

According to the distribution and assemblage of biomarkers, the crude oil and oil shows from Santanghu basin can be classified into two groups, such as Mesozoic coal-derived oil and oil of upper paleozoic lake facies genesis. The crude oil from Xishanyao formation of Jurassic system in well Tangcan 1 is a representative of Mesozoic coal-derived oi1. It has the characteristics of odd-carbon predominance in normal alkane series,Pr/Ph value is high(>4. 0). In addition,the relative abundance of C24-C26 tetracyclic terpanes is higher than C19-C25 tricyclic terpanes(> 1.0), C19 and C20 components are higher than C21 and C23 in tricyclic terpanes, C31 hexcyclic hopane is identified but gammacerane is not, C29 components are unusually abundant in C27-C29 steranes. The crude oil is originated from a coal-measure source rock. Oil from upper Paleozoic lake facies genesis includes the oil shows from wells of Tangcan 3, Tiao 2 and Tiao 3. They don't have the characteristics of odd carbon predominancein normal alkanes and have lower Pr/Ph value. Besides,the tricyclic terpanes are more abundant than tetracyclic terpanes (only C24 is detected) and the relative abundance of Ca3 and C21 components is higher than tricyclic terpanes, C31 hexcyclic hopane is substituted with abundant gammacerane and β-carotane. The abundance of C27 steranes are comparatively higher,which are originated from the upper Paleozoic lake facies source rocks.