东濮凹陷CO2气资源潜力评价

东濮凹陷在下古生界奥陶系风化壳与下古近系Es₃¹地层发现了高含CO₂气层，通过气源对比分析，古近系Es₃¹的有机气体来源下第三系碎屑岩地层生成的油型气，CO₂则来源于石炭-二叠系的煤在二次生烃中伴生CO₂气与海相碳酸盐岩高温分解的无机CO₂混合形成的；对东濮凹陷两类CO₂气源岩高温模拟实验可知，石炭-二叠系煤生气能力是奥陶系灰岩的9倍，煤生成的气体70%~80%为甲烷，含少量的CO₂，而灰岩90%以上为CO₂气，煤是东濮凹陷最重要的气源岩；通过计算认为：东濮凹陷CO₂气的资源量为980×10⁸m³，相当于常规天然气资源量的1/4，具有较大的资源潜力。

ASSESSMENT OF CO2 RESOURCES POTENTIAL IN DONGPU SAG

Gas layers with high CO2 content have been recognized in the Lower Paleozoic Ordovician weathering crust and in the Paleogene Es31 in Dongpu sag. Gas source correlation shows that the organic gas in the Paleogene Es31 is petroliferous gas generated by the Paleogene clastic rocks, while the CO2 is a mixture of the associated CO2 generated during secondary hydrocarbon generation of Permo Carboniferous coal, and the inorganic CO2 sourced from high temperature decomposition of marine carbonates. High temperature simulation of the two types of CO2 gas source rocks in Dongpu sag shows that the gas generating capacity of the Permo Carboniferous coal is 9 times larger than that of the Ordovician limestone. The gas generated by coal contains 70-80% methane but small amount of CO2; while the gas generated by the Ordovician limestone contains over 90% CO2. Thus coal is the most important gas source rocks in Dongpu sag. The CO2 resources in Dongpu sag is estimated to be at 980×108m3, which accounts for one fourth of the conventional natural gas resources, thus the resource potential of CO2 is relatively large in the study area.