Following very successful conferences in recent years, the EAGE held their 3^rd Conference on Carbon Capture and Storage Potential in Perth, Western Australia on 12-13^th August. With more than 130 delegates from 56 organisations and 10 countries, opportunities to share knowledge and discuss recent developments in the CCS industry were plentiful. ERCE Principal Development Geologist Kathe Trigg attended the event, and here are a few of the highlights from her time there:

1. Chevron announced that the Gorgon CCS Project, which began operation in August 2019, has recently reached the big milestone of 10 Million Tonnes injected. Great news from what is still the largest commercial CO2 injection project globally, and one that struggled in early years to meet the high expectations of the project. Annual injection is currently ~1.6MTA, and the team is confident that that rate will increase with upgrades to pressure management wells that are currently in progress.

2. Woodside Energy Geophysicist James Deeks highlighted the challenges in using 4D seismic data as part of the MMV plan for Woodside’s Angel CCS project. Angel is a depleted gas field, and the team has found that conventional 4D seismic is unlikely to be able to detect the movement of CO2 in the likely range of pore space saturation (< 3%). Instead, the team is investigating the potential use of timelapse gravity modelling. This technique is showing significant promise, and it’s definitely a technology to keep an eye on.

3. Technology is also advancing in the ways in which Storage Capacity is being calculated for CCS projects. Previously the realm of static and dynamic models with some 1D or 2D geomechanical analysis, most Operators discussed their move towards Coupled Mechanical Earth Models (MEM) as the preferred methodology for calculating the storage potential of a depleted reservoir or saline aquifer. The majority of projects are using 2 parameter coupled MEMs, those being Geomechanical – Dynamic models. However, some companies are even going as far as having 3 parameter coupled MEMs, with Geochemical – Geomechanical – Dynamic coupling becoming increasingly common. As part of this discussion, many practitioners discussed the de-coupling of the thermal plume and the saturation (or pressure) plume. According to one speaker, in a specific project the thermal plume is about half the lateral extent of the saturation plume, but that the faults were reactivated far more easily by temperature changes than by changes in pressure. Detailed 4D subsurface analysis is required to fully understand the impacts of CO2 injection – to a greater detail than was presented previously.   

4. Mark Trupp, previously involved with Chevron’s Gorgon CCS project (now at Mitsui), and Rob Root (Gorgon Asset Development Manager at Chevron) discussed the need to be able to pivot quickly when faced with insights from early reservoir performance of a CCS project. In hindsight, it may have been prudent for the Gorgon Project to begin injection with more conservative rates, rather than expect 4MTPA at start-up. The ability to slowly ramp up to increased rates while identifying and rectifying any issues is now seen as a must, both for the effective management of the project internally and the perception of the project externally. Mitsui will be implementing that lesson learnt when they begin injection in their Cygnus Hub project.  

5. With few Operating CCS projects globally, learning and knowledge sharing of actual implementation is in its infancy. It was therefore refreshing and exciting to hear from the South Australian government that they will be publishing Santos’ MMV plan for their Moomba CCS project, which is due to begin production shortly. The South Australian government will then report annually against the public MMV plan, allowing the energy industry and the Australian community-at-large to understand in near-real time how the project is performing. Hopefully, this will aid in knowledge sharing within the industry and increased positive perception amongst the wider community that CCS is a successful way to aid Net Zero targets and aspirations.

6. Sophie Thompson and Jai Louis, both working on the Angel CCS project for Woodside Energy, discussed a series of lessons learnt on the project. An interesting one that could be considered a small, but that has been found to have a large impact is a change to traditional subsurface terms when discussing CO2 movement. In conventional oil and gas projects, subsurface professionals tend to talk about reservoir quality in terms on Net-to-Gross (NTG), Porosity and Permeability. However, using these terms when discussing the movement of CO2 can lead to confusion. Lower NTG values can lead to higher stored volumes of CO2 than higher NTG values, due to the increase in residual and solubility trapping in a slower moving plume, which may result from a lower NTG. This can be hard to grasp when talking only in terms of NTG. Similarly, changes in pressure and temperature can lead to differences in CO2 density, and therefore the lateral area of the storage site. Moving from the traditional oil and gas terms to more helpful CCS terms such as “slow or fast plume movement” or “large or small plume footprint” can help communicate uncertainties more clearly and allow all parties to understand the true impact of the uncertainty.

Overall, the quality of presentations was high, with many interesting case studies presented from Japan, South Korea, Malaysia and Australia. The 4^th EAGE Conference on Carbon Capture and Storage Potential is definitely one to mark on the calendar.