Santos WA PVG Pty Ltd (Santos), on behalf of the Coniston-Van Gogh Production Joint Venture titleholders (Santos WA PVG Pty Ltd [52.501% ownership] and INPEX Alpha Ltd [47.499% ownership]) operates the Van Gogh, Coniston and Novara fields located in WA-35-L which recovers oil in production licence area WA-35-L using the Ningaloo Vision floating production, storage and offloading (FPSO) vessel.
Production rates are declining and end of field life is currently estimated to be H1 2025. As a result, Santos has commenced decommissioning planning activities.
The operational area is located approximately 45 km north-northwest off the Cape Range Peninsula in Western Australia. Water depths range from 340 m to 400 m.
Santos now submits the Ningaloo Vision Cessation of Production and Floating Asset Removal (COPFAR) EP to cover activities listed below:
- disconnection of the FPSO from the disconnectable turret mooring (DTM) and its permanent sail away for its decommissioning
- the ongoing presence of all infrastructure on title until end state decommissioning
- floating asset removal (DTM, risers and removal of mooring lines if deemed safe and practicable to do so
- implementation of inspection, monitoring, maintenance, repair (IMMR) activities until all wells are plugged and abandoned and subsea infrastructure is decommissioned
- Additional flushing of a portion of production flowlines
- Removal of a 910m section of the Coniston Novara Production Flowline B.
Typical IMMR activities carried out may include:
• equipment inspections
• maintenance/repair/replacement of equipment as needed
• cathodic potential measurements;
• clearing debris (e.g. calcareous marine growth) using high pressure water jetter and/or flapper tool;
• Close Visual Inspection (CVI) and measurements of critical components; and
• seabed burial and environmental surveys (including using geophysical type equipment. E.g. side scan sonar)
The floating asset and damaged section of production flowline B removal activities covered in this EP are planned to commence in Q4 2025/Q1 2026.
Waste from removal of equipment will be managed through application of the waste management hierarchy. Santos will seek opportunities to reuse and recycle materials where possible.
Activities have estimated durations and timings as outlined below.
- FPSO disconnection and sail away – Planned for H2 2025 over approximately 2 – 5 days
- FAR and flowline removal – planned to occur within 12 months of FPSO sail away
- IMMR can occur any time of the year and campaigns are expected to take around 30 days.
Activities would be continuous over a 24-hour period and could be conducted over multiple and concurrent campaigns during these time frames. Timing and duration is subject to change due to project schedule requirements, vessel availability, unforeseen circumstances and weather.
Activities may be supported by one, or a combination of the following marine ‘vessels’:
- Tugs including Anchor Handling Tugs;
- Barges;
- Crew transfer;
- Heavy Lift;
- Tow vessel and
- Dive Support and rescue.
IMMR activities are expected to be conducted with one vessel with minimum one ROV and/or an unmanned autonomous vessel. Helicopters may be used to transfer crew and assist in emergency.
