库车坳陷迪北气藏侏罗系储层古流体特征与油气充注史

Characteristics of paleo-fluid and hydrocarbon charge history of Jurassic reservoir in Dibei gas field,Kuqa depression

采用流体包裹体岩相学、显微测温及储层颗粒荧光定量等方法,对库车坳陷迪北气藏侏罗系储层古流体特征与油气充注史进行了研究。结果表明,迪北气藏侏罗系储层发育两期烃类包裹体:第Ⅰ期为黄绿色的液态烃包裹体,为早期原油的充注;第Ⅱ期为发蓝白色荧光的气液包裹体与无荧光的气态烃包裹体,显示晚期天然气充注。盐水包裹体均一温度呈双峰型分布特征,也指示两期油气充注。储层颗粒荧光定量分析表明,迪北气藏侏罗系储层中的油可能为不同源或不同成熟度原油的混合。结合迪北气藏沉积埋藏史研究得出,迪北气藏经历了两期油气充注:第一期为18~16 Ma期间的油充注;第二期为5~3 Ma期间的天然气充注。西域组沉积期以来构造运动强烈,气藏经历改造在构造低部位成藏。

Petrography microthermometry of fluid inclusion,quantitative grain fluorescence(QGF)and quantitative grain fluorescence on extract(QGF-E)are used to study the paleo-fluid characteristics and hydrocarbon charging history of Jurassic reservoir in Dibei gas field,Kuqa depression,Tarim Basin.The results show that the Jurassic reservoirs in Dibei gas field develop inclusions with two stages:the first stage is liquid inclusion with yellow-green color,which indicats the filling of early oil;the second stage is gas-liquid inclusion with blue-white fluorescence color and gas inclusions with non-fluorescence color,which indicats that the late gas was charged.The homogenization temperature of inclusions indicats the two stages of hydrocarbon charging.QGF and QGF-E show that the oil in the Jurassic reservoir of the Dibei gas field may be a mixture of different origins or different maturity.Combined with the sedimentary history of Dibei gas field,it is suggested that the Dibei gas field has experienced two stages of oil and gas charging.The first is the filling of oil between 18~16 Ma.Gas charging period in the second stage is 5~3 Ma.Since the Xiyu period,the tectonic movement has been strong and the gas field accumulate at low parts.