焉耆盆地包裹体特征和伊利石测年对油气成藏期次的指示

Indication of Oil-Gas Migration & Accumulation with Fluid Inclusion Characteristics and Illite Dating in Yanqi Basin

焉耆盆地侏罗系储层中流体包裹体主要分布于三工河组和八道湾组，其均一温度多为101～110℃和121～130℃，组分中的正构烷烃碳数呈双峰态，前主峰碳为nC18或C20，后主峰碳为nC26或nC27。这些特征指示盆地在侏罗纪中晚期发生两次成藏作用；而储层中自生伊利石同位素测年同样指示了博湖坳陷北部凹陷油气的两次成藏时期，即中晚侏罗世（142．26～183．15Ma）和白垩纪（75．07～142．26Ma）。南部凹陷和本布图构造带的油气成藏期分别为中侏罗世、中晚侏罗世一早白垩世，同时纵向上在同一构造带内，K—Ar年龄随埋深增加而变大，反映油气自构造低部位向高部位逐渐充注运移和调整。

The fluid inclusions of Jurassic reservoir in Yanqi basin Northwest China mainly distribu ted in Sangonghe Formation and Badaowan Formation, its homogeneous temperature mostly was 101 - 110℃ and 121 - 130℃. The N alkane carbon atomic numbers assumed two kurtosis in its inclusion component, the first main peak carbon was nC18 or nC20, the following main peak carbon was nC26 or nC27, these characteristics instructed that the basin occurred two oil-gas accumulation phases during the midlate Jurassic; But the autogenetic illite isotope dating in its reservoir instructed similarly two oil-gas accumulation phase in the north depression of the Bohu sag, namely the Mid-Late Jurassic （142. 26 - 183.15 Ma） and the Late Cretaceous （75.07 - 142.26 Ma） ,thereinto the oil-gas accumulation phases in the south topographic depression and the Benbutu structure belt respectively were the Mid Jurassic and the Mid - Late Jurassic - Early Cretaceous, the K - Ar dating increased with its burying depth in the identical structure belt on the longitudinal, which reflected that the oil-gas injected, migrated and adjusted gradually from the low structure spot to the high structure spot.