In this paper, we propose the framework of risk assessment system for CCS, carbon capture and storage, especially for enhanced recovery of gas, oil and gas hydrates. Based on the protocol proposed by US and European institutions, the framework of enhanced CCS has been modified to improve the functions of geological-based performance assessment. We have developed our original risk assessment system for CCS, regarding the geological features of specific storage sites. Some results on numerical simulation of CO2 migration and the estimation of the leakage of CO2 in pathways are presented and discussed for the further development. In addition, the stimulation of gas hydrates using CO2 would be possible CCS methods at offshore area. The original method of CO2-CH4 substitution in the production of gas hydrates is also introduced in the present study.