Abstract: Geological storage of carbon dioxide (CO2) into deep saline aquifers is a leading-edge technology of greenhouse gas emissions reduction. The paper investigates China's first full-chain carbon capture and storage (CCS) project, i.e. Shenhua CCS demonstration project. Combining actual operation condition, the site of demonstration project in Ordos Basin is selected for the study. The relevant parameters are extracted to establish the geological model that is used to simulate multilayer injection of CO2 into deep saline aquifers. In order to analyze migration and distribution of CO2 while and after injection, the relationship between injection capacity and storage mechanisms of CO2 is investigated in detail. Additionally, it is also investigated on changes of formation pressure, CO2 phase, CO2 mole fraction and pH value. The numerical simulation shows that when CO2 is injected into deep saline aquifers, it is almost sequestered into the top of the reservoir. When the injection capacity is stronger, CO2 is injected into more layer formations, and the injection volume of CO2 is relatively bigger. The injected CO2 bears a very complicated phase state in deep saline aquifers. It is mixed with a free gas, trapped and dissolved phases. Simultaneously, when an injection rate is different, main phase types of injected CO2 into deep saline aquifers are different and they change with time. The change pattern of pH values is also different because of strength of seepage effect caused by different injection rates. All exploratory studies are aiming at building a good foundation to optimize future schemes of the demonstration project.

Key words: CO2 geological storage, deep saline aquifer, migration and distribution, numerical simulation, Shenhua CCS