松辽盆地长岭断陷老英台—达尔罕凸起CO2分布特征及成因分析

松辽盆地长岭断陷老英台凸起区广泛分布CO₂气层或与烃类气体伴生的CO₂,其含量和组成非均质性明显,不同井区或同一井区不同层位气层中CO₂的相对含量及同位素组成均可能存在明显差别,表明其成因十分复杂。揭示研究区CO₂的成因机理,不仅具有理论意义,对研究区天然气勘探也具有重要的现实意义。根据CO₂组成、同位素分布特征,结合伴生烃类气体分析,可知研究区深层CO₂既有无机成因,也有有机成因,或者两者混合成因。其中,CO₂含量相对较高的营城组气层中的CO₂主要为无机成因气,而CO₂含量较低的登娄库组气层中的CO₂为有机成因或有机—无机混合成因。登娄库组有机成因CO₂与烃类气为同期成藏;营城组CO₂有与烃类气同期形成的,但大规模的无机成因的CO₂为新近纪之后晚期成藏的。 

Distribution characteristics and genesis of CO2 in the Laoyingtai-Daerhan Uplift, the Changling Fault Sag, the Songliao Basin

CO₂ gas or CO₂ accompanied with hydrocarbon gas is widely distributed in the Laoyingtai Uplift of the Changling Fault Sag,the Songliao Basin.Contents and compositions of CO₂ are different.Relative contents of CO₂ and isotopic compositions may be obviously different between different wells or different gas formations in the same well,indicating complicate genesis.Studies of genetic mechanism of CO₂ are important not only in theory,but also for natural gas exploration in the region.Based on CO₂ composition and isotopic distribution features,combined with hydrocarbon gas studies,CO₂ deep in the study area is both organic and inorganic origin,or mixed.CO₂ in the Yingcheng Formation which contains much CO₂ is mainly inorganic origin.CO₂ in the Denglouku Formation which contains little CO₂ is organic origin or mixed.Organic origin CO₂ in the Denglouku Formation accumulates at the same time with hydrocarbon gas.Part of CO₂ in the Yingcheng Formation accumulates at the same time with hydrocarbon gas;however,large accumulations of inorganic origin CO₂ take place after Neogene.