RMNER Network Meeting

Publication Overview

The three day meeting included themes on risk assessment methodologies, risk communication and mitigation strategies as well as environmental research. There was an emphasis on potential impacts of CO₂ in marine environments, natural variability and the unscheduled release of CO₂ from pipelines. Coverage also included formation fluid release, overburden features, international initiatives and environmental impact assessments notably the Peterhead – Goldeneye project. 

Publication Summary

• Risk assessment for CO₂ storage sites has matured significantly, as compared with five years ago. Wellbores still represent the most-likely pathway for unwanted fluid migration in most storage scenarios.
• Very substantial work on pipeline safety has been achieved. Pipelines have the potential to cause big acute impacts or small leaks.
• Field experiments indicate that, in the event of CO₂ leakage to the surface, terrestrial environmental impacts are likely to be low.
• The discharge from offshore storage sites needs to be kept in proportion. 1Mm3 of hypersaline brine is discharged daily by Saudi desalination plants.
• Fluid discharges from the oil industry and natural seeps need to be distinguished from leaks. Natural seeps also occur in Australia, the USA and Europe.
• Environmental assessment in the marine environment can leverage great scientific understanding, datasets and techniques.
• Environmental impacts of CO₂ leakage at the seaflore are localised and fast recovery is evident in shallow, coastal areas with tidal flushing. The complexity of natural variations in marine environment is a significant factor when attempting to establish a baseline and monitoring programmes
• Chimney characterisation is better understood. Pockmarks often represent palaeo fluid channels. The absolute value of sub-surface permeability, and relative differences inside and outside a chimney structure, is poorly constrained.
• CCS in comparison with other industries is being held to higher standards.
• Reference risks cases should include cases with probabilities.
• The potential impacts of scaled-up impact need to be placed into context i.e. risk per mega tonne of mitigation should be a parameter.
• New sensors are under development and will need to be tested and reviewed. Identified Further Work and Opportunities
• A serious full-scale experimental investigation of wellbore leakage (on the COOLTRANS model).
• Structure research on impacts to be better connected to risks, and vice-versa. Reference to risk cases would be helpful.
• There is a need for a consistent narrative about relative risks (climate, other environmental impacts vs CCS). In this context, there needs to be a clear understanding what baselines are, and how they will be applied (for leakage signal detection over background variability, or for measurement of impact, or both).
• Scaling up to large deployment needs more attention.
• Wellbore risk and remediation needs more detailed investigation.
• Unlike onshore pipeline failure, where entire projects (e.g. COOLTRANS, CO₂PIPEHAZ, CO₂QUEST) have now achieved considerable understanding through comparison of simulations and experiments, offshore CO₂ pipeline failure has not been studied and is not well understood. An opportunity exists to rectify the current knowledge gap.
• Formation water leakage – monitoring, impacts, EIAs, of analogous releases would be beneficial (eg produced water from oil and gas operations).
• Empirical research on the characterisation of brines, their potential impact on natural systems and modelling of their dispersion in marine environments needs further research.
• Sensors for formation fluid leaks are being developed and will need to be field tested. A review of new sensors and their potential benefit to early detection is recommended.
• Effects of leakage on soil fertility are not yet known.
• Development and testing of new ratio-based techniques (aka process-based) offshore to distinguish leakage from natural activities. Recommendations
• Address the further work above.
• More R&D attention on the performance of alternative mitigation and other corrective measures?
• Net Environmental Benefit Analysis (NEBA) for CCS in event of leaks? A NEBA is a methodology for comparing and ranking the net environmental benefit associated with multiple mitigation alternatives to an environmental incident such as a CO₂ leak.
• Further research is required to quantify the impact on the CCS chain and marine environment of an offshore CO₂ pipeline failure.