在松辽盆地南部深层有机成因烃类气藏的勘探中，多处发现了高纯度的无机成因CO2气藏（以往多数学者认为是幔源成因），给烃类气藏的勘探优选带来很大的困惑。本项目拟在前期对CO2 气藏和烃类气藏成藏时间、期次和序次等成藏特征多年研究的基础上，通过火山岩脱气实验和CO2 对烃类气的驱替试验，重点解决两个问题：1）核查以火山岩脱气方式释放出的CO2 量对形成高纯CO2 气藏的贡献，论证无机CO2 的成因类型；2）探讨后期产生的CO2 气藏对早期形成的烃类气藏排替、置换过程，重点查明两类气的耦合差异成藏机理。最终为研究松辽盆地深层受后期CO2 影响、改造的烃类气藏成藏机理、控制因素、分布规律和有利勘探区优选等科学问题提供依据，提高烃类气藏勘探的成功率。

High-purity carbon dioxide natural gas reservoir has been discovered in the exploration of deep organic origin of hydrocarbon gas in the south of Songliao basin (mantle origin is considered previously), which leads to great confusion in exploration and optimization of hydrocarbon gas reservoir. Based on years of research of reservoir forming time, stage and sequence of CO2 gas reservoir and hydrocarbon gas reservoirs, by study of volcanic degassing experiments and displacement tests of hydrocarbon gas reservoirs by CO2, two major problems were solved: 1) Verifying the contribution of CO2 emanated from Volcanic degassing to high-purity CO2, and demonstrate the genesis of inorganic CO2；2) discussing displacement and replacement process of CO2 gas reservoir generated at a later stage to hydrocarbon gas reservoirs generated at an earlier stage, especially the coupling difference and hydrocarbon accumulation mechanism. Based on the properties above, it is benefit for further study of effect of CO2 at later stage in Songliao basin. Furthermore, hydrocarbon gas accumulation mechanism, controlling factors and distribution law are expected to be improved. At the same time, it is conducive to determine the location of favorable exploration areas. The ultimate goal is to increase the success rate of hydrocarbon gas reservoir exploration.