Ensuring good injection techniques

When a suitable CO2 storage site is discovered, the gas must be injected in the safest and most efficient manner.

Illustration: Hydro 

This is a technology we must learn before the "moon landing" can begin. Injecting CO2 into underground reservoirs will take place by means of wells and pipelines that are similar to those used for the extraction of oil and gas, but there are still a whole series of new problems to be solved. We must understand how the injection can take place, and we must know what is happening in the reservoir with the injected gas, says Elin Skurtveit.

NGI is participating in the research project Inject CO2, which is supported by CLIMIT program in RCN. The project focuses on the processes that are related to the injection phase. The injection of large amounts of CO2 will result in both a pressure build up and geochemical reactions in the reservoir. It is important to have control over these processes.

It is important to control the injection pressure in order to avoid mechanical damage of the cap rock, but at the same time, the pressure must be sufficiently high for the gas to spread into the reservoir, explains Aker.

The project will also try to establish the best injection techniques. The best strategy may not be to pump a steady stream of CO2 into the reservoir. It may be better to use pulse injection, mix the gas with water before injection or even produce water from the reservoir, adds Skurtveit.

There is a need for better understanding of how CO2 reacts when it comes into contact with the original pore fluid in the formation during injection. Research has shown that this may affect the reservoir pressure over large areas.
  
 
Facts CO2 Inject
 

The participating research institutions are NGI, University of Oslo, and Institute for Energy Technology and Department of Physics, University of Bergen.

Project CO2 Inject: IFE, Dr.  NGI's project leader: Dr. Eyvind Aker