松辽盆地昌德东CO2气藏形成机制及成藏模式

通过对松辽盆地北部昌德东地区CO2气藏中天然气组分、天然气成因、气藏特征、断裂及火山岩相等研究,探讨昌德东地区CO2气藏的形成机制及成藏模式.研究表明,昌德东地区CO2为幔源成因,烃类气为油型气与无机烃类气混合成因;芳深9井-芳深701井区为CO2气藏,芳深6井-芳深7井区属高含CO2气藏,二者是两个互不连通的气藏系统.松辽盆地深层CO2气藏的形成机制可概括为:深部热流底辟体的顶部是CO2的储集库.基底大断裂向下收敛于拆离带并沟通CO2气源,CO2通过基底大断裂和古火山通道向上输导并在适当圈闭中聚集成藏.运聚通道组合类型的差异以及运移过程中天然气的重力分异作用是导致芳深9井-芳深701井区和芳深6井-芳深7井区气藏中CO2含量差异的根本原因.图5表3参32

Formation and pool-forming model of CO2 gas pool in eastern Changde area, Songliao Basin

With the study on gas composition, gas genesis, reservoir characteristics, faults and volcanic lithofacies of CO2 gas pool in eastern Changde area in Songliao Basin, the pool-forming mechanism and model are established. The results show that CO2 gas in the pool is mantle origin, the hydrocarbon gas is mixture of oil-type gas and inorganic hydrocarbon gas; the CO2 gas pool in FS9-FS701 well field and the gas pool with high CO2 content in FS6-FS7 well field are two separate reservoirs unconnected. The forming mechanism of deep CO2 gas pool in Songliao Basin is as follows: the top of deep heat-flow diapris is full of CO2, and large basement fault converges downward to the detachment zone and communicates CO2 gas source, then CO2 migrates upward into proper traps through basement fault and ancient volcanic conduit. It is pointed out that different types of migration and accumulation pathways and the natural gas gravitational differentiation during the migration process are the fundamental reasons for the difference of CO2 content between the two gas pools.