The gas field, also named Lingshui 17-2 that sits 1,500 meters below the sea surface in the South China Sea, was producing 10 million cubic metres a day, the report said.
Gas flowing in from 11 production wells are being pumped via a subsea pipeline to onshore receiving points in Hong Kong and south China's Guangdong province, before joining the national gas grid, the report added.
In full production, the field will be able to supply 3 billion cubic meters of gas a year, or roughly 1% of China's gas demand.
With proven reserves of 100 billion cubic meters and wells sunk 4,000 meters below the seabed, the project shored up confidence that China's energy majors possess the technical and operational acumen to fulfill their gas ambitions, Reuters reported in July.
(Reporting by Chen Aizhu; Editing by Shailesh Kuber)