Self sealing of leaks in subsea CO2 reservoirs

The overall purpose of the project is to increase the confidence in long term storage of CO2 in offshore reservoirs. In the project, the problems associated with the reservoir integrity with respect to leakage back to the seawater and ultimately the atmo sphere, are to be investigated. In several publications, the possibility for self plugging of leaks from CO2 from an offshore reservoir through the escaping CO2 forming hydrates in the pores of the overlying cap rock/ seabed sediment have been investigate d. At sufficiently deep locations and cold enough seabed water temperatures, conditions may prevail that allow forming of stable enough hydrates in the sediment pores. The project has the following objectives a) The primary objective of the application is to investigate experimentally under which conditions CO2 escaping from a leak in an offshore CO2 reservoir can (partially) seal the leak by forming hydrates in the overlying cap rock /seabed sediment. Answers to the following questions are intended t o be answered in the scope of the project: a. water depth, seabed temperature and conditions of the overlying cap rock/seabed sediment allow forming and binding of released CO2 as hydrates in to the cap rock or seabed sediment pores, consequently pluggin g potential leaks? b. What are the mechanical properties of the resulting hydrate?sediment structure? c. Estimation of residual leakage rates? d. Risk estimation of the leak reappearing? b) The secondary objective of the project is to investigate adding chemicals in the vicinity of the leak in order to enhance the plugging effect and/or stability of the resulting hydrate plug. Answers to the following questions should be included in the scope of the project: a. Can chemicals be added to the reservoir s tream during filling that aids ?self sealing? capabilities? b. Are there other reactions with CO2 that can be used for sealing of leaks c. Can chemicals be injected to aid this/other measures