金刚烷类化合物与库车坳陷克拉2构造凝析油的形成机理研究

借助于色谱和色谱—质谱分析技术，对库车坳陷克拉2构造和牙哈构造带原油中轻烃、链烷烃、多环芳烃、甾萜烷生物标志化合物和金刚烷类化合物进行了系统分析。结果表明：克拉2构造凝析油的轻烃和全烃组成中特别富含芳烃化合物，甾烷、萜烷中明显富含低分子量化合物如三环萜烷系列、孕甾烷和升孕甾烷，这一特征明显不同于牙哈构造带来源相似的原油和凝析油，显示其形成机理的特殊性。此外，克拉2构造凝析油和牙哈构造带原油中普遍存在烷基单金刚烷系列和烷基双金刚烷系列，但只有克拉2构造凝析油中检测出烷基三金刚烷系列。定量结果表明克拉2构造凝析油中金刚烷类化合物的浓度较牙哈构造带原油高约一个数量级，这些特征表明克拉2构造凝析油的成熟度明显高于牙哈构造带原油。依据甲基单金刚烷指数MAI和甲基双金刚烷指数MDI与镜质体反射率RO间的对应关系，发现克拉2构造凝析油对应的RO值约为1.9%，热裂解程度大于97%，属于典型的热裂解原油，这与富含芳烃的特征吻合；而牙哈构造带原油对应的RO值约为1.2%～1.4%，且不同构造单元原油的热裂解程度变化较大，介于20%～80%之间，这与后期高成熟油气侵入程度有关。

Study on diamondoids and genetic mechanism of condensates from the Kela 2 structure in the Kuche Depression

By aid of gas chromatography and gas chromatography-mass spectrometer，light hydrocarbons，chain alkanes，polycyclic aromatic hydrocarbons，biomarkers such as steranes and terpanes，and diamondoids in crude oils from the Kela 2 structure and Yaha structural belts in the Kuqa Depression were analyzed. The results show that various aromatic hydrocarbons are abnormally abundant in C_6-8 light hydrocarbons and whole oils;C_19-26tricyclic terpanes in m/z 191 mass chromatogram,and pregnane,homopregnane in m/z 217 mass chromatogram are relatively high in crude oils from the Kela 2 structure,but these biomarkers in similar crude oils from the Yaha structural belts are obviously low,suggesting that crude oils from the Kela 2 structure may have an unusual genetic mechanism. Moreover,alkyl adamantanes and alkyl diamantanes are detected in crude oils from the Kela 2 structure and Yaha structural belts,but alkyl trimantanes are only present in condensates from the Kela 2 structure,and the concentrations of various diamondoids in condensates from the Kela 2 structure are more an order of magnitude than those in crude oils from the Yaha structural belts,showing that maturity of condensates from the Kela 2 structure is much more than those of crude oils from the Yaha structural belts. Based on the relationship between MAI,MDI and RO values,RO values are about 1.9% in condensates from the Kela 2 structure,and their cracking extent may be more than 97%,showing that those condensates are typical cracking oils;RO values are about 1.2%-1.4% in crude oils from the Yaha structural belts,cracking extent of crude oils from different structure units varies from 20% to 80%,depending on filling extent of high-mature oils and gas in late period.