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.Type Ⅰ is 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;Type Ⅱ is 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;Type Ⅲ features 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;Type Ⅳ is relatively low mature oil with low content of gammacerane but high Pr/Ph

and occurs in the Dong-ying 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.