CNOOC Ltd, which acts as operator for Southeast Sumatra, said the 55 million standard cubic feet per day (mmscf/d) was from four production wells.

Phase one development facilities included a processing platform, three underwater pipelines and one underwater cable in about 30m of water about 120km off West Java.

Hong Kong-listed CNOOC Ltd said most of the natural gas would be supplied to power plants owned by PT Perusahaan Listrik Negara (PLN), the government-owned electricity company of Indonesia.

Gas delivery from phase two was expected to start in early 2007.

CNOOC Ltd executive vice-president Liu Jian said the successful start of phase one showed CNOOC could safeluy and effectively develop overseas oil and gas fields.

CNOOC Ltd holds a 65.5% interest in the production sharing contracts in Southeast Sumatra, as well as acting as operator. Its partners include Inpex Sumatra, KNOC Sumatra, Orchard Energy Sumatra BV, Fortuna Resources (Sunda), Talisman UK (Southeast Sumatra) and Talisman Resources (Bahamas).

CNOOC Ltd is a 70.64% subsidiary of China National Offshore Oil Corporation, China's largest offshore oil and gas producer.