柴达木盆地西部第三系油气晚期成藏特征

柴达木盆地西部第三系盐湖相烃源岩成熟期为晚第三纪,成烃期相对较晚;盆地西部大部分构造圈闭是在晚第三纪末—第四纪形成,只有少数构造圈闭是在早第三纪末期形成,总体上讲构造圈闭形成比较晚;流体包裹体均一化温度测定结果表明,盆地西部油气藏存在两次充注,第一次是在晚第三纪早期,第二次是在晚第三纪末期,充注期次相对比较晚;对成藏期次综合分析后确定盆地西部油气成藏时期比较晚,为柴达木盆地油气藏形成的一大特点.

Characteristics of the late hydrocarbon accumulation of the Tertiary in the western Caidamu Basin

The mature phase of the hydrocarbon source rock of the salt lake facies of the Tertiary in the western Caidamu is in late Tertiary,and it is later than other basins.The most of the structural traps were formed in the period from early Tertiary to Quanternary,and a few of them are formed in the final stage of early Tertiary.On the whole,the formation of all the structural traps is later.The analysis result of the homogenization temperature of the fluid inclusions shows that there are two petroleum injections to the hydrocarbon reservoir in the west of Caidamu Basin.The first occurs in early period of late Tertiary,and the second occurs in the final stage of late Tertiary,which are all later on the whole.Therefore,the later hydrocarbon accumulation is a key character of the reservoir in the western Caidamu Basin.