准噶尔盆地腹部莫索湾地区油气成藏条件与成藏模式

准噶尔盆地腹部莫索湾地区是一个为二叠系生油凹陷所围绕的继承性隆起区，南面又面临侏罗系的生烃区，具有充足的油气来源。该区拥有四大套储盖组合：以石炭系火山岩体为储集层，其上的风化壳为盖层；以二叠系夏子街组为储集层，下乌尔禾组为盖层；以上乌尔禾组和中下三叠统为储集层，上三叠统为盖层；侏罗系自储自盖。该区圈闭以构造圈闭为主，形成早、容积大。因此该区具有优越的油气成藏条件。对该区地层压力结构的研究表明，该区存在上下两个流体压力封存箱：下封存箱包括二叠系和三叠系，形成于三叠纪末或侏罗纪早期；上封存箱主要包括侏罗系下部，形成于白垩纪晚期。该区存在的3次成藏事件与封存箱的演化有重要关系。三叠纪和早侏罗世是下封存箱的箱内成藏期，源于风城组的油气在二叠系和三叠系形成原生油气藏；中晚侏罗世和白垩纪是下封存箱的箱外成藏期，源于二叠系的油气在下封存箱外的侏罗系形成油气藏；第三纪至今，对于上、下封存箱都是箱内成藏期，上封存箱形成侏罗系自生自储气藏，下封存箱则形成源于二叠系的油气藏。莫索湾地区常压带、上封存箱和下封存箱都具有广阔的勘探前景。图5参2（张年富摘）

Fluid compartment and hydrocarbon accumulation in Mosuowan area in central part of Junggar basin

Mosuowan area, located in the central part of Junggar basin, is a continuously developed uplift surrounded by Permian hydrocarbon generation depression and with Jurassic generation center to the south. This area with its sufficient hydrocarbon source, favorable reservoir beds in the Carboniferous, Permian, Triassic and Jurassic strata, and large,early formed structural traps is one of the most favorble areas for hydrocarbon accumulation in the basin. Investigation on the formation pressure structure showed that there are two fluid compartments in the sedimentary column of this area. The lower compartment is in Permian and Triassic and formed in late Triassic or early Jurassic, the upper compartment is in the lower part of Jurassic and formed in late Cretaceous. The formation and evolution of fluid compartments in this area had significant influence on hydrocarbon accumulation. Hydrocarbon from Permian source rocks accumulated mainly in the lower compartment during late Triassic and eary Jurassic time. The breakthrough of seal during middle and late Jurassic led to the forming of hydrocarbon accumulation inJurassic outside the lower compartment. After the forming of upper compartment and the closure of seal break in late Cretacoous, the two compartments became no hydraulic communication and hydrocarbon accumulation only took place separately within two compartments.