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Reactive Transport Modelling of CO2 Injection into a Carbonate Formation, Middle East
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, The Third Sustainable Earth Sciences Conference and Exhibition, Oct 2015, Volume 2015, p.1 - 5
Abstract
This study describes injection of CO2 into a carbonate formation in the Middle East, which is considered as potential option for permanently storing CO2. It is predicted that CO2 predominantly migrates into a high permeability layer near the top of the reservoir and reaches a potentially conductive fault at the end of the injection period. Seepage of CO2 may occur along this fault during the post-injection period, causing upward migration of CO2 throughout the formation. The results show that CO2 dissolution and dissociation causes lowering of the pH to 4.7 in the plume, as well as some calcite dissolution. The molality of elemental Ca increases several orders of magnitude, although the amount of calcite dissolution remains limited. This suggests that the geochemical impact is relatively small in case of the closed system studied. The computed porosity changes are relatively larger than those computed for the SACROC carbonate reservoirs, where CO2 was injected for enhanced oil recovery. This is explained by mineral precipitation and possibly by higher initial Ca molalities in the SACROC modelling study.