IEAGHG Monitoring Network – ‘Monitoring Expertise Showcase for Post-Closure Monitoring’

Publication Overview

This was a little different from usual webinars, whereby the Steering Committee aimed for a more interactive and informal experience for the audience with a scenario-based exercise.
Susan Hovorka (BEG at UTexas) introduced the hypothetical site scenario. She emphasised that the aim of the event was to learn about post-closure monitoring options, with an informal ‘game’ to engage panellists with the audience in thinking about CO₂ storage sites and measurement, monitoring and verification (MMV). This is a hypothetical site with some gaps in the information, in reality the site characteristics would be much better understood for storage projects and months of planning would have been done prior to making any sort of decisions on monitoring programmes. The hypothetical site scenario is described in figure 1, below. This ‘site’ will be injecting for 25 years, into 50 metre thick sandstone at a depth of 1.5km.

Publication Summary

The webinar was concluded by Tim Dixon who thanked the panellists, Steering Committee and audience for their valuable input into the event. Many topics were looked into around the area of post-closure monitoring for CO₂ storage sites, and several key messages were drawn from the discussion:

– There is a wide range of available technologies that can be deployed for post-closure monitoring programmes, all of which have different merits,

– Post-closure monitoring is very site specific,

– Effective and proper post-closure monitoring requires a full and detailed site characterisation, baseline knowledge and a lot of data from the area before a site can be approved,

– It’s important to do both operational and post-closure monitoring,

– Leakage is defined as CO₂ that fluxes across the ground surface and not out of the reservoir; greenhouse gas emissions accounting is concerned with the CO₂ reaching the air or water column,

– More work is needed on deep monitoring methods informing the near surface methods in real time,

– The subsurface is known well but operators need to be prepared for any changes,

– It is likely and recommended that monitoring programmes will use a variety of technologies that complement one another,

– Shallow and surface monitoring may be needed as assurance monitoring,

– Responding to stakeholder concerns is an important facet of monitoring programmes,

– Environmental liability differs in different regions,

– False positives are an important factor to consider when choosing technologies,

– Understanding of post-closure monitoring approaches is still immature,

– Geologic CO₂ storage is safe by design, and is designed to be safe.