板桥凹陷原油轻烃地球化学特征

黄骅坳陷板桥凹陷原油轻烃整体表现为富链烷烃、贫芳烃和环烷烃含量相对较高的特征。C₇和C₆轻烃参数一致指示原油母源有明显高等植物有机质的输入，母质类型为混合型。庚烷值和异庚烷值较高，原油生成温度在108.7~129.8℃之间，说明原油主要为成熟阶段的产物。Mango参数K₁值大致在1.0附近，符合轻烃稳态催化理论；K₂值较高，源岩具有淡水湖相沉积的特点。碳环优势指数六环优势明显，指示出陆相原油的特点。根据轻烃参数特征可将研究区原油分为:来源于典型混合型有机母源的正常成熟原油、生物降解型原油以及来源于偏腐泥型母质的特殊成因原油3种类型。

Geochemical Characteristics of Light Hydrocarbons in Banqiao Sag

Light hydrocarbons of crude oils in Banqiao Sag are all relatively rich in the alkanes and deficient in aromatic hydrocarbons.The naphthenic hydrocarbon content is relatively high.C₇ and C₆ also show that the crude oil originated from mixed organic matter.Heptane value and isoheptane value are high,the generating temperature is between 108.7℃ and 129.8℃,which indicate oil is the product of mature stage.Mango parameter K₁ is around 1.0,and its distributions are consistent with the chemically stable structure model of light hydrocarbons. K₂ is relatively high,the depositional environment is freshwater lacustrine,the three ring preference 6RP is greater,suggesting the oil belongs to terrestrial oil.According to these parameters,the crude oil can be divided into three classes,mixed organic material normal mature crude oil,biodegraded crude oil and crude oil with special cause which is derived from the partial sapropel organic matter.