塔里木盆地库车坳陷在侏罗系时期发育有湖相-沼泽相环境、白垩系则发育扇三角洲-滨浅湖相沉积环境。目前在库车坳陷大宛齐地区已发现煤成油与湖相油，但目前对该地区混源油中三环萜烷的分布特征研究尚不充分，通过对大宛齐油田原油中三环萜烷的分布模式及其地球化学意义进行了系统研究。由于大宛齐油田原油相对轻质，首先将原油分离出饱和烃与芳香烃组分，随后对饱和烃进行络合处理以除去正构烷烃，继而进行色谱-质谱分析，最后以煤成油与湖相油为端元油对混源油的混合比例进行定量研究。结果表明大宛齐油田不同类型原油具有以下特征：煤成油中三环萜烷分布为C₁₉TT > C₂₀TT > C₂₁TT > C₂₃TT >C₂₄TT > C₂₅TT，具有较大的C₂₄TeT/C₂₆TT比值，C₂₈TT、C₂₉TT含量极低；湖相油中三环萜烷分布为C₁₉TT < C₂₀TT < C₂₁TT < C₂₃TT >C₂₄TT > C₂₅TT，具有较小的C₂₄TeT/C₂₆TT比值，含一定含量的C₂₈TT、C₂₉TT；混源油中三环萜烷分布为C₁₉TT > C₂₀TT > C₂₁TT <C₂₃TT > C₂₄TT > C₂₅TT，具有中等C₂₄TeT/C₂₆TT比值，含有一定含量的C₂₈TT、C₂₉TT，其分布模式与前两种原油均有相似之处，但其他地球化学参数介于两种典型原油之间，表明该类原油为煤成油与湖相油的混合产物。通过建立混源油混合程度的定量模型，确定混源油中煤成油的贡献率主要介于55% ~ 90%。本研究结果不仅能为塔里木盆地大宛齐油田油源对比及混源油贡献比例的定量确定提供了模型，同时也为该地区不同类型原油的勘探开发提供了重要的地球化学依据。

The Kuqa Depression of the Tarim Basin developed lacustrine-swamp depositional environments during the Jurassic period and fan delta-shore-shallow lacustrine environments during the Cretaceous period. While both coal-derived and lacustrine oils have been discovered in the Dawanqi area of the Kuqa Depression, previous studies lack a comprehensive understanding of tricyclic terpane distribution patterns in mixed-source oils from this region. Due to the relatively light nature of the crude oils from Dawanqi Oilfield, the oil samples were first separated into saturated and aromatic hydrocarbon fractions. The saturated hydrocarbons were then treated by complexation to remove n-alkanes, followed by GC-MS analysis. Finally, quantitative assessment of mixing ratios in the mixed oils was conducted using coal-derived and lacustrine oils as end-members. Results reveal distinct characteristics among different oil types: coal-derived oils show a tricyclic terpane distribution of C₁₉TT > C₂₀TT > C₂₁TT > C₂₃TT > C₂₄TT > C₂₅TT, with high C₂₄TeT/C₂₆TT ratios and very low C₂₈TT and C₂₉TT contents; lacustrine oils exhibit C₁₉TT < C₂₀TT < C₂₁TT < C₂₃TT > C₂₄TT > C₂₅TT distribution, with low C₂₄TeT/C₂₆TT ratios and moderate C₂₈TT and C₂₉TT contents, mixed-source oils display C₁₉TT > C₂₀TT > C₂₁TT <C₂₃TT > C₂₄TT > C₂₅TT distribution, with intermediate C₂₄TeT/C₂₆TT ratios and moderate C₂₈TT and C₂₉TT contents. While the mixed-source oils share distribution patterns with both end-members, their other geochemical parameters fall between those of the two typical crude oils, indicating their mixed origin. Quantitative modeling of mixing degrees suggests that coal-derived oil contributes approximately 55% ~ 90% to the mixed-source oils. This study not only provides a model for oil-source correlation and quantitative determination of contribution ratios in mixed-source oils from the Dawanqi Oilfield but also offers valuable geochemical insights for the exploration and development of different oil types in this region.