Volume 47

Numerical investigation into CO2 sequestration as hydrates and its long-term stability in submarine sediments Yuhang Gu, Zhenyuan Yin, Xuejian Liu, Shuaijun Li

Abstract

Under suitable temperature and pressure conditions, CO2 can combine with water to form solid CO2 hydrates. Hydrate-based CO2 sequestration in subsea sediments is an alternative option to mitigate global warming. In this work, we developed novel simulation codes and simulated CO2 sequestration processes in subsea sediments based on site W19 in the Shenhu area. The results show that CO2 hydrate massively forms after the end of injection and gradually expands into low-permeability cap that can stably exists for 100 years. The hydrate cap greatly restricts upward migration of liquid CO2, forcing it to gradually transform into dissolved phase and hydrate phase, which makes hydrate-based CO2 sequestration feasible. Permeability, salinity, thermal conductivity of the formation and CO2 injection rate all have significant impacts on the sequestration performance, which provides guidance for site selection and optimization of injection scheme.

Keywords CO2 sequestration, CO2 hydrate, feasibility analysis, long-term stability, numerical code, CCUS