辽河滩海地区原油地球化学特征及成因类型

Geochemical behaviors and genetic types of crude oil in tidal zone and shallow water area of Liaohe oilfield

辽河滩海地区为辽河油田油气生产的重要后备接替区,该区原油包括正常油、稠油和超稠油。稠油和超稠油主要分布于浅层,与生物降解、氧化作用有关。根据原油的沉积环境、母质类型和成熟度特征,将原油划分为4类:Ⅰ类为伽马蜡烷含量相对较高、姥/植比相对较低和"V"字形规则甾炕分布的成熟原油,分布在笔架岭油田和月海油田中浅层;Ⅱ类成熟度偏高,低伽马蜡烷和"L"形规则甾烷分布,分布于月海油田相对深层的沙河街组三段;Ⅲ类具有高三环萜烷、高伽马蜡烷和"L"形规则甾烷分布的特征,为海南11和葵花16东营组三段原油,处于滩海东部生烃凹陷两侧;Ⅳ类以较低成熟度、低伽马蜡炕和高姥/植比区别于前3类原油,分布在葵花岛油田东营组。4种成因类型的原油指示辽河滩海地区存在多套有效烃源岩,月海油田深层和滩海东部葵花岛油田东营组仍具有广阔的勘探前景。

Tidal zone and shallow water area of Liaohe oilfield are important regions for production replacement. The crude oil types in the study area includes normal oil,heavy oil and super-heavy oil,of which the later two are mostly distributed in th shallow layers and are related to biodegradation and oxidation.According to sedimentary environment,organic matter types and maturity,the crude oils are grouped into 4 types.TypeⅠis mature oil with relatively high content of gammacerane,low Pr/Ph and ＇V＇ normal sterane,and occurs in the middle to shallow reservoirs of Bijialing and Yuehai oilfields;TypeⅡis high mature oil with low content of gammacerane and ＇ L＇ normal sterane,and occurs in the relatively deep third member of Shahejie Fm in Yuehai oilfield;TypeⅢfeatures in high contents of tricyclic terpane,and gammacerane and ＇ L＇ normal sterane,and occurs in the 3rd member of Dongying Fm of Hainan-11 and Kuihua-16 oilfields on both sides of the hydrocarbon kitchen; TypeⅣis relatively low mature oil with low content of gammacerane but high Pr/Ph,and occurs in the Dongying Fm of Kuihuadao oilfield.The four genetic types of crude oil indicate that there are several favorable source rocks developed in the tidal zone and shallow water area of Liaohe oilfield,and the deep layer of Yuehai oilfield and the Dongying Fm of Kuihuadao oilfield still have great petroleum potential.