R&D on stabilized CO2 geological storage free from leak risk

提出了一种基于残余气和溶解度捕集的CO_2地质封存技术。首先，我们对750 - 1,000米深度含水层的典型条件下的最大捕获CO_2饱和度进行了实验评估。为了避免CO_2在水中的溶解性和CO_2的可压缩性给实验带来的困难，利用等温膨胀过程中的压力-体积关系估算了捕获气体的饱和度。尽管CO_2密度、粘度和界面张力都有变化，但捕获气饱和度在24.8%~ 28.2%之间。因此，与盖层物理圈闭相比，单位体积的残余气和溶解度圈闭至少可封存38.8%的CO_2。根据该方案估算，日本的储存潜力为71.6GtCO_2，相当于日本53.6年的排放量。通过残余气体和溶解性捕集的储存不仅增加了储存能力，而且提供了位于靠近大排放源的位置。

A CO_2 geological storage technology based on residual gas and solubility trapping is proposed. First, we experimentally evaluated the maximum trapped CO_2 saturation for typical conditions of aquifers at depths from 750 to 1,000m. To avoid the experimental difficulty due to the dissolution of CO_2 in water and the compressibility of CO_2, the trapped gas saturations were estimated from the relationship between pressure and volume under an isothermal expansion process. The trapped gas saturation is in the range from 24.8 to 28.2% despite the variation of CO_2 density, viscosity and interfacial tension. Therefore, at least 38.8% of CO_2 would be stored by residual gas and solubility trapping per unit volume as compared to physical trapping with cap rock. The storage potential of Japan by the proposed scheme is evaluated to be 71.6 Gt CO_2, which corresponds to the emission in Japan for 53.6 years. The storage by residual gas and solubility trapping not only augments the storage capacity but also provides the sites that are located close to the large emission sources.