Chinese offshore operator CNOOC Ltd has started drilling the country’s first well for reinjecting carbon dioxide into the reservoir at its Enping oilfield in South China Sea’s Pearl River Mouth basin.

The Enping 15-1-A11H well is being drilled three kilometres from the Enping 15-1 oilfield, through which CO₂ will be reinjected into a “dome” geological structure.

CNOOC Ltd said the structure is like a “giant bowl” buckled underground, which has strong natural sealing that can cover the CO₂ stably for a long time.

The carbon capture and storage scheme involves facilities including a CO₂ compressor skid, molecular sieves and coolers to capture up to 300,000 tonnes per annum of CO₂ — equivalent to planting 14 million trees, according to CNOOC Ltd. The aim is to capture up to 1.46 million tonnes of CO₂ over the project’s lifespan.

CNOOC Ltd late last year started operations at the Enping oil complex in the South China Sea.

The Enping complex consists of the Enping 15-1, Enping 10-2, Enping 15-2 and Enping 20-4 fields in average water depth of 90 metres, about 190 kilometres southeast of Hong Kong.

The facilities include two drilling production platforms and one unmanned wellhead platform, which accommodates 48 production wells and is equipped with a remote production function for operations during typhoons.

The project is expected to achieve peak production of around 35,500 barrels per day of oil in 2024.

Produced liquids are to be sent to one of the platforms for initial processing before being piped to the Hai Yang Shi You 118 floating production, storage and offloading vessel for further treatment.