CO2 injection for IOR and storage: opportunities and challenges for the North Sea

CO2 injection for improved oil recovery (IOR) has been extensively investigated and is commercially pursued in many onshore fields around the world. Concerns over greenhouse gas emissions are leading to the investigation and realisation of its potential as a carbon storage method in recent years. With right reservoir conditions, injection of CO2 into oil reservoirs can result in incremental oil recovery and permanent storage of CO2 in geological formation. The North Sea has been considered as a good CO2 storage site for Europe. It has been accepted that there is little major technical challenges for CO2 IOR projects, but there are economic constrictions if high cost anthropogenic CO2 (such as from power plants) is used for IOR and storage, especially for offshore operations. A high oil price and the introduction of the carbon emission credits may have a positive effect on promoting CO2 storage projects in the North Sea. In this paper, a general review of CO2 IOR in the North Sea is given, considering the current field experience, CO2 IOR and storage potentials, technical and economic barriers. Case studies for CO2 IOR applications in a few North Sea fields are presented. Apart from economic concerns, technically, there are some challenges that need to be addressed for North Sea operations, these include insufficient reservoir characterisation, large well spacing, the lifespan of the offshore infrastructures and extra cost for adapting platform and equipment to handle CO2.