Molecular Dynamics Simulation of CO2 Storage in Reservoir Pores with a Dead-End

Abstract

The carbon capture, utilization and storage (CCUS) technique is widely applied in order to solve energy shortages and global warming, in which CO2 storage plays an important part. Herein, the CO2 storage in reservoir pores with a dead-end is investigated using a molecular dynamics simulation. The results indicate that, when a CO2 molecule flows through a reservoir pore towards its dead-end, it is readily captured inside said dead-end. When the pressure difference of the CO2 injection increases, the transport speed of the CO2 becomes faster, and the storage efficiency increases. The rate constants for the absorption of the carbon dioxide at 5 MPa, 10 MPa, and 15 MPa are 0.47 m/s, 2.1 m/s, and 3.1 m/s. With the same main channel, a narrower dead-end with less oil molecules would cause a smaller spatial potential resistance, which would lead to a faster CO2 replacement and storage process. The 3 nm main channel with a 1.5 nm dead-end model had the highest absorption rate of 5.3 m/s out of the three sets of models with different dead-ends. When the dead-end’s width was constant, the rate constants for the absorption of carbon dioxide in the 6 nm main channel with a 1.5 nm dead-end model was 1.8 m/s, which was higher than that of the 3 nm–1.5 nm model. This study investigates the mechanism of CO2 storage in reservoir pores with a dead-end at the molecular level and provides a scientific basis for the practical application of CO2 storage.