松辽盆地高含CO2气藏储层包裹体气体的地球化学特征

对松辽盆地高含CO₂气藏储层包裹体及其气体组分的地球化学特征研究发现,储层中CO₂包裹体不发育,包裹体中CO₂的地球化学特征和气藏中气体的地球化学特征有比较大的差别,包裹体中的CO₂显示有机成因,而气藏中的CO₂显示无机成因;但包裹体中与气藏中的烃类气体的同位素特征却比较一致。造成包裹体上述特征的原因一是无机幔源CO₂的充注速度快,包裹体来不及生长;二是在CO₂充注以前,储层已经被烃类气体所饱和,在储层缺水的地质环境下不适宜包裹体的形成。最后结合地质特征认为,CO₂的充注发生在烃类气体充注以后。

Geochemical behaviors of gases from inclusions in high-CO2 reservoirs,the Songliao Basin

Study on inclusions and geochemical behaviors of gases from these inclusions in high-CO₂ reservoirs in the Songliao Basin shows that CO₂ inclusions are underdeveloped in the reservoirs and the geochemical behaviors of CO₂ from inclusions differ greatly with that from the reservoirs.The CO₂ from inclusions is of organic origin,while that from the reservoirs is of inorganic origin.However,the isotopic characteristics of hydrocarbon gases from gas pools and inclusions show certain consistency.The reasons behind all these include that the mantle-derived CO₂ charged too quickly to allow the growth of inclusions and that the reservoir rock was saturated by hydrocarbon gases before CO₂ charging,forming geological settings unfavorable for inclusion growth due to lack of water needed.Based on the geological settings of the Songliao Basin,it is suggested that CO₂ charging happened later than hydrocarbon gas charging.