Australia’s Triangle Energy and Pilot Energy — the Cliff Head joint venture — are preparing to start front-end engineering and design work for what could become Australia’s first offshore carbon capture and storage (CCS) project.

The Cliff Head CCS scheme is being touted as having best-estimate contingent carbon dioxide storage potential of 9.7 million tonnes, which would facilitate the injection of 665,000 tonnes per annum of CO2 over 15 years.

Start-up of the CCS scheme at the mature shallow-water oilfield offshore Western Australia is being targeted by 2025, Upstream has reported.

Over the past six months, the joint venture’s technical teams, along with CO2Tech — its carbon storage subsurface adviser — have carried out a full technical assessment of the storage potential across the WA-31-L tenement area.

This work expanded key technical models to cover the entire WA-31-L and contiguous area — expanding into Pilot’s 100%-held WA-481-P exploration licence.

Revised development plan

The expanded technical data set resulted in a 50% increase in the CCS project’s best-estimate contingent storage to 9.7 million tonnes.

This upgraded resource has resulted in a revised CCS development plan with a new CO2 injection well to be drilled downdip from the Cliff Head oilfield instead of converting five existing wells, with the existing wells being retained for pressure maintenance and monitoring.

While the capital cost of the simplified development plan is under review, it is expected to fall within the previous guidance of A$110 million (US$73.46 million) for 665,000 tpa injection capacity with up to a further A$60 million to expand injection capacity to 1.1 million tpa.

At the envisaged initial injection rate of 500,000 tpa of CO2, that would equate to the planting of 57 million trees, Pilot earlier said.

Meanwhile, technical analysis indicates the potential CO2 storage capacity at Cliff Head is up to 50 million tonnes, before the CO2 plume reaches a tenement [block] boundary.

On Wednesday, the joint venture confirmed it has applied to the National Offshore Petroleum Titles Authority (NOPTA) to declare “an identified greenhouse gas storage formation” across its block WA-31-L — the initial regulatory approval for the Cliff Head offshore CCS project.

Following this declaration, the joint venture said it would complete all steps to enable the final investment decision for the Cliff Head CCS project, including all regulatory submissions — the partners will need to apply for a CO2 injection licence.

Other key steps towards taking a final investment decision include lining up the engineering, procurement and construction management contractor; performing detailed FEED work and project costings; and securing capital.

Triangle has a 78.75% interest in the Cliff Head joint venture, with Pilot holding the remaining 21.25%.

However, NOPTA’s approval for the declaration over WA-31-L will trigger restructuring of the partnership, which will see Pilot holding a 60% direct operating stake in both the Cliff Head joint venture (the existing oil project) and Cliff Head CCS, with Triangle holding a direct 40% participating interest in both projects.