[H-SC07] 地球温暖化防⽌と地学（CO2地中貯留・有効利⽤、地球⼯学）

[HSC07-P07] ナノ空隙でのCO₂/H₂O/白雲母系の動的接触角に関する分子動力学的検討

*志賀 正茂^1,2、徂徠 正夫¹、愛知 正温²、本田 博巳² (1.産業技術総合研究所、2.東京大学)

キーワード：CO2地中貯留、濡れ性、分子動力学

CO₂ Geological Storage (CGS) is one of the most promising technologies to reduce the amount of CO₂ emissions into the atmosphere. Enhanced oil recovery in addition to the sequestration in the geological formation has been actively studied, and these are considered to be a significant strategy for sustainable energy development. In order to conduct the project safely, it is necessary to predict and understand the sealing performance of the caprock. This is evaluated by the threshold value of the capillary pressure. This pressure is formulated as Young Laplace equation; the capillary pressure is proportional to 2Γcosθ/a. (Γ: interfacial tension between CO₂ and brine, θ: contact angle, a: radius of the pore throat) Water-receding contact angle, which is represents the wetting behaviors in the drainage process, should be evaluated. Therefore, there have been a lot of experimental measurements of the dynamic contact angle. However, there is no data in the nano scale, which is the actual scale of the caprock in the CGS site. CO₂ and H₂O confined in the nano pore throat is likely to behave in a different manner. This is because the effect of the surface forces working on the fluid phases from the mineral surface is much larger than those in the macroscopic systems.

Considering the importance of studying the wettability in nano scale and its difficulty in direct measurements, we calculated the contact angle by using molecular dynamics simulation. We obtained both advancing and receding contact angles. Moreover, we studied the shape of the interface both at meniscus and film regions, which have crucial roles in wettability alteration.