Abstract:

       The CO2 storage in oil reservoirs is one of the most effective ways of reducing the greenhouse gas emission, which is
based on the mechanisms of structural and stratigraphic trapping, residual gas trapping, dissolution trapping and mineral trapping.The universal pyramid method is introduced to assess the CO2 storage capacity for the oil reservoirs. Subei basin has many oil reservoirs with low permeability and water content. Dongtai sag is better than Yancheng-Funing sag on the CO2 storage potential.Gaoyou depression and Jinhu depression have the greatest potential of CO2 storage among the secondary geological units. A series of the small tectonic units in this area are more suitable for CO2 storage, and beneficial to the preservation of late stage. Subei basin has obviously vertical dichotomy on the sealing ability of CO2 storage. The lower cap rocks of upper Cretaceous system and Paleocene series have better sealing capabily than the upper cap rocks of the Eocene epoch. Based on analyzing the mechanism of CO2 storage in oil reservoirs and combining with geological and structural conditions of Subei basin, we estimated that the theoretical storage capacities of CO2 is 1.5054×108 t and the effective storage capacities of CO2 is 0.0828×108 t ~ 0.4421×108 t, which shows the great potential of CO2 storage in Subei basin, Jiangsu Province.

Key words: geological storage, carbon dioxide storage enhanced oil recovery (CO2-EOR), storage mechanism, capacity
evaluation, Subei basin