库车坳陷克深大气田白垩系致密砂岩储层古流体地球化学特征研究

采用包裹体岩相学、均一温度、盐度、含油包裹体丰度、储层颗粒荧光定量实验分析方法,对库车坳陷克深大气田白垩系巴什基奇克组储层致密砂岩样品进行测试,剖析克深大气田深层致密砂岩储层古流体地球化学特征与油气充注。结果表明,克深大气田发育两期油气包裹体,分别为发亮蓝色荧光的轻质油包裹体与灰黑色的气态烃包裹体。克深大气田包裹体均一温度分布存在130~140 ℃与150~160 ℃两个主峰值,相应的古盐度值为16%~10%与12%~4%,表明有两期烃类流体充注,其中天然气高强度充注发生在2.5 Ma以来。含油包裹体丰度分布在2.1%~13.4%之间,QGF指数为2.2~9.6,QGF-E强度为20~38 pc,揭示克深大气田形成过程中曾经存在强度较弱的轻质油充注。

Geochemical Characteristics of Paleo-fluid in Tight Sandstone from Cretaceous Reservoir in Keshen Large Gas Field,Kuqa Depression

To study the geochemical characteristics of paleo-fluids and hydrocarbon charging in tight sandstone reserviors of the Keshen large gas field, we analyzed the fluid inclusion petrography, homogenization temperature, salinity, oil inclusion abundance via quantitative fluorescence technique on the Bashenjiqike Formation sandstone in the gas field. The study shows that there were two generations of hydrocarbon inclusions: bright-blue fluorescence oil inclusions and gray-black gas ones. Homogenization temperatures of coeval aqueous inclusions show two peaks at 130-140 ℃ and 150-160 ℃, with corresponding paleo-salinity of 16%-10% and 12%-4%. This indicates two stages of hydrocarbon fluid filling, in which the high-intensity natural gas was charging since 2.5 Ma. The abundance of oil inclusions ranges from 2.1% to 13.4%, QGF index ranges from 2.2 to 9.6, QGF-E intensity are from 20 pc to 38 pc. These results reveal a weak light-oil filling in the formation of the Keshen large gas field.