关键词: 碳捕集与封存, CO2地质封存, 咸水层

Abstract: A full-chain carbon capture and storage (CCS) demonstration project was implemented in 2010 by injecting 105 tons of super-critical CO2 per annum down into the brine-saturated low-permeability sandstone and carbonate aquifers at depths of more than 1 620 m in the northeastern Ordos Basin, China. Based on the site-specific geology and the observational data, a numerical injection model is developed based on TOUGH2-MP/ECO2N to simulate the on-going injection process and hence evaluate the injection-induced behavior of the multiphase flow system in the reservoirs. The pressure build-up and the dynamics of the CO2 saturation plume are assessed. The results show that the model developed can reproduce well the performance of the storage reservoir. The CO2 plume spreads outward symmetrically in the horizontal plane. The Liujiagou sandstone aquifer is the most favorable reservoir for CO2 storage at this site. After 3 years of consecutive injection of CO2, the CO2 plume front in the Liujiagou unit is located at about 550 m in 3 years after the commencement of the injection. The pore pressure buildup due to injection is slightly less than 15 MPa. The plume in the Liujiagou unit is expected to migrate to around 700 m away from the injection well after 53 years of post-injection. The major storage reservoir is at the depth interval 1690-1699 m, which contributes over 80% of the storage capacity of the entire reservoir system. The contribution of the reservoirs to the total storage capacity descreases with the depth downward. The leakage of CO2 into the seals is negligible (<0.05%) during the 53 years of simulation period.

Key words: carbon capture and storage (CCS), CO2 geological storage, saline aquifer