Introduction

This workshop came about to address a recommendation from the CSLF on offshore CCS. This second workshop built on the conclusions and recommendations from the first workshop in 2016 by continuing the theme of ‘how to do’, and including sessions on how to find storage, monitoring developments, CO₂-EOR potential offshore, and infrastructure options, with presentations from Norway, the UK, the Netherlands, Australia, South Africa and Japan. New to all attendees were presentations on the US Department of Energy (DOE) -supported US projects looking at offshore storage in sedimentary basins in the Gulf of Mexico, the Atlantic and in basalts in the northern Pacific. Conclusions and recommendations were agreed, with a certain focus on infrastructure issues with the aim of engaging with operators of offshore infrastructure to make them aware of the opportunities from CCS and CO₂-EOR.

The workshop concluded with a field trip to look at all the elements of an integrated CCS project: a large CO₂ source at the Air Products capture project in Port Arthur, CO₂ transport options including, ship, barge, rail, Denbury’s Green pipeline and CO₂ hub potential at GT-Omniport, and the geology of a potential storage site offshore, all of these components being in close proximity in this part of south eastern Texas. 

Key messages

• Offshore storage site selection methods are becoming mature.
• A conservative approach to project development favours assessing multiple sinks and multiple sources, so that the elimination of one site does not derail the whole project.
• Case studies from South Africa and Australia indicate the importance of systematic project refinement including down-selecting potential storage sites. 
• Project risk is significantly lowered in cases where dense subsurface data sets are available, injectivity is known, and sinks are in proximity to sources. 
• Monitoring plans are successfully passing through negotiation with regulators. 
• Pragmatism in balancing risk reduction with cost management is illustrated in cases from Peterhead, ROAD, Sleipner and Snohvit.
• AUV environmental monitoring reduces cost and reduces human safety issues.
• Multiple approaches to overburden and water column monitoring are demonstrated.
• CO₂ -EOR continues to be considered as a prospective part of storage, for example in the Norwegian and UK North Sea, the Gulf of Mexico, and basins globally.  Information and analysis continues to increase (see major summary by CSLF CO₂ -EOR task force, due 2017).
• Timing and cost issues arise with re-use of infrastructure offshore.
• Subsea solutions for adding CO₂-EOR to existing platforms are in development. The components exist, but there is still a need to qualify their use with CO_2.
• Many options exist for infrastructure, both new and reused, and the choices will be site specific.