BG India, a unit of the British giant, "achieved first oil production from the Mukta-B (MB), a 4 legged Wellhead Unmanned Platform in the offshore Bombay basin", it said in a statement.
It however did not give details of the production rate.
The British firm holds 30 per cent interest in the Panna- Mukta oil and gas fields. State-owned Oil and Natural Gas Corp (ONGC) has 40 per cent stake while Reliance Industries holds the rest 30 per cent.
BG India President and Managing Director Shaleen Sharma said: "This is a significant milestone for BG India and the culmination of an integrated team effort by all functions and contract parties."
Incremental development of the existing fields via well intervention and infill drilling campaigns, as well as evaluating new projects and further development opportunities, is being planned, the statement said.