An evaluation of hydrocarbon deposit tightness in aspect of CO2 sequestration

Depleted hydrocarbon deposits due to large capacity and proven tightness are often considered as prime candidates for CO2 sequestration in geological structures. The tightness of these structures is mainly connected with the existence of water saturated overbunden rocks of very low permeability which form a natural barrier for the migration of hydrocarbons. This paper explains the sealing mechanisms of caprocks resulting from capillary forces at the interface of hydrocarbon – water and carbon dioxide – water contact. Other ways of caprock leakage due to rock fracturing or reactivation of natural faults and fi ssures were also investigated.