Introduction

This report is intended to provide a summary of key learning points from recent IEA Greenhouse Gas R&D Programme (IEA GHG) activities related to the geological storage of CO₂.

The report summarises key learning points from IEA GHG operating Phase 5, which commenced in 2005 and effectively coincided with the publication of the IPCC Special Report on Carbon Dioxide Capture and Storage (IPCC SRCCS). That publication provides a useful reference point for the subsequent knowledge on storage acquired through IEA GHG activities.

IEA GHG activities fall into two main categories: technical studies, selected by programme members and sponsors from proposals drawn up by IEA GHG staff and from other sources; and three international research networks on CO₂ storage, covering the topics of monitoring, risk assessment (RA) and wellbore integrity. A fourth network on the modelling of CO₂ geological storage has been launched in February 2009, following the success of a workshop on that theme, organised jointly by IEA GHG, BRGM, Schlumberger and CO₂GeoNet.

IEA GHG studies are typically undertaken by contractors, selected through a competitive tendering process. IEA GHG studies typically involve desk-based reviews undertaken over a six month period, followed by an independent expert review process. The fact that these studies are selected from a wider list of proposals by IEA GHG members, ensures that the studies focus on topical themes and address or identify knowledge gaps.

Network activities revolve around annual meetings, with venues rotated around the world to avoid regional bias. The meetings are held over 2 to 3 days and agendas, set in advance by organising committees that include IEA GHG staff and independent technical experts drawn from both industry and academia, are designed to maximise the opportunities for discussion and debate. Network meetings are particularly effective at highlighting gaps in knowledge and research; these findings can be used to stimulate further work, including IEA GHG studies or other activities. Examples include a questionnaire-based, IEA GHG study on regulator understanding of CCS risk assessment in 2007 following a risk assessment network meeting, and the creation and maintenance of the IEA GHG Monitoring Selection Tool following discussions in the monitoring network.

Other IEA GHG activities on CO₂ geological storage include participation in practical R&D or demonstration projects, normally to assist with dissemination of results. Another important role for IEA GHG is as co-organisers and ‘guardians’ of the GHGT conference series. Some general learning points from the GHGT9 conference held in Washington DC during November 2008, have been included in this report.

Recommendations

Future research into geological storage of CO₂, including IEA GHG studies and research network activities, should be guided by the knowledge gaps identified by IEA GHG activities and summarised in this report. Current IEA GHG activities are addressing many of these gaps in a number of areas:

• A study on the use of setting and use of coefficients to refine regional storage capacity estimates has been commenced in September 2008. This study will draw on modelling and field experience from around the world and build on the output and findings of the CO2CRC report,

• The key issues of pressurisation and brine displacement for deep saline formations will be discussed in the modelling and risk assessment networks and may be the subject of a future IEA GHG study,

• Wellbore integrity issues are being addressed through a study being undertaken by TNO on behalf of IEA GHG, in addition to the ongoing work of the research network,

• Leakage scenarios will continue to be considered by the risk assessment network,

• Knowledge gaps in storage science, concerning the need for improved understanding of geochemical processes and application of coupled predictive models, will be key topics for discussion in the recently formed IEA GHG modelling network,

• IEA GHG is co-funding a study on site characterisation by DNV that aims to develop qualitative ‘best practice’ procedures, whilst a second proposed study by ARC will consider quantitative criteria,

• A study to be commissioned in 2009 will address the issues surrounding the design of injection schemes for CO₂ geological storage,

• The IEA regulators network is providing an important contribution to the rapid development of regulation in various parts of the world,

• During the GHGT9 conference in Washington, over-pressurisation of aquifers and brine displacement were highlighted as two linked, key issues that could affect the total capacity available for storage in saline aquifers. These are amongst the issues being considered by the new modelling network,

• The monitoring network will continue with the goal of assisting the development of cost-effective monitoring programmes.