松辽盆地北部深层天然气系统成藏史研究

ACCUMULATION HISTORY OF MATURAL GAS SYSTEMS IN THE NORTHERN DEPTH OF SONGLIAO BASIN

松辽盆地北部深层烃源岩有机质类型以 型为主 ,烃源岩成熟度达到了湿气 -干气阶段 ,为一个相对独立的天然气系统。对烃源岩的埋藏史、热史、生烃史的正演模拟和由包裹体均一温度确定的天然气运聚时间 ,与充注期次逆演相结合的研究表明 ,徐家围子断陷天然气成藏时间主要自早白垩世泉头期到白垩纪晚期 ,天然气系统的关键时刻为晚白垩世中晚期 (72Ma) ;莺山断陷的成藏时间早于徐家围子断陷 ,天然气系统关键时刻为晚白垩世早期 (90 Ma)。两个断陷均为一次性充注成藏 。

The source rocks in the northern depth of Songliao Basin make a feature of Type Ⅲ organic matter and high maturation of wet/dry gas generation . According to burial, thermal and hydrocarbon generation modelling, as well as analysis of gas accumulating history by organic fluid inclusions, the paper indicates that the critical times of the Xujiaweizi and Yingshan fault depression gas systems are 72 Ma and 90 Ma, respectively, both being charged with gas in one phase. It suggests that the two gas systems are representatives that have undergone a long period of preservation since late Cretaceous.