Developing good monitoring methods
If CO2 storage will help to slow down the greenhouse effect in the long run, the stored gas must remain in place in deposit sites for hundreds of years or up to a 1000 years.
Photo: Alligator film /BUG / StatoilHydro
This means that reservoirs with stored CO2 should be monitored for leaks, but the monitoring need probably not last for 1000 years. Indeed, it is very difficult to imagine that a political decision today will be respected after such a long time in the future.
It is essential to monitor the injection phase, which might last 20-30 years, the monitoring must subsequently be continued for at least some decades until we have ensured that the CO2 is permanently and safely deposited. How long it takes, will depend on several factors such as the site specific geological conditions, but time is on our side. This means that the chance of leakage decreases over time as CO2 molecules are dissolved in the original pore fluid (oil or water) and chemically or hydro-mechanically bonded to the reservoir rocks, predicts Eyvind Aker.
Monitoring of CO2 behaviour in aqueous reservoirs onshore, should probably be performed with greater accuracy than the water deposits beneath the seabed. This is mainly because the damage caused by a leak to more shallow lying freshwater aquifers onshore can be more serious than at sea.
It is however important that we manage to develop monitoring methods that are affordable and can cover large areas. Monitoring CO2 in the subsurface would rerpresent a significant cost, which might tempt future decision-makers to save money, believes Aker.
Monitoring the behavior of CO2 in reservoirs is an important part of the work in the Research SUCCESS, which is one of eight research centers for environmentally friendly energy (FME), established by the Norwegian Research Council in February 2009.
The center will play a leading role in the overall development of monitoring technology and methods for CO2 storage. NGI is the activity leader for the part of research work that deals with the monitoring of the reservoir behavior, and whether or not the CO2 is leakproof.
Fakta SUCCESS
SUCCESS: Subsurface CO2 storage - Critical Elements and Superior Strategy
The Norwegian Research Council allocates 10 million a year to SUCCESS, which is led by Christian Michelsen Research (CMR) in Bergen. Director: Arvid Nøttvedt, CMR, NGI's project manager: Eyvind Aker, a senior physicist
In addition to the NGI and CMR, other participating research institutions are IFE, NIVA, Unifob, University of Bergen, University of Oslo and the University Center on Svalbard.