Oil and Natural Gas Corporation (ONGC) has made a significant oil discovery to the west of its prime Mumbai High fields in the Arabian sea, a senior official said. The discovery in well WO-24-3 is estimated to hold an in-place reserve of about 20 million tonnes, he said.

Mumbai High, India's biggest oil field, currently produces 205,000 barrels of oil per day (just over 10 million tonnes per annum) and the new find would add to that production in less than two years time.

"In all, nine objects or zones were tested and all of them were found to be hydrocarbon bearing. The last object tested flowed 3,300 barrels of oil," he said. Oil and Natural Gas Corporation is carrying out a further appraisal of the discovery and has intimated upstream regulator the Directorate General of Hydrocarbons (DGH).

"This is a mid-sized discovery but a significant one," the official said. The new find, which comes almost 50 years after Oil and Natural Gas Corporation began production in Mumbai High, will help the company maintain production levels from the basin for a longer time than currently estimated.

Mumbai High is ONGC's flagship oil producing assets. It along with other small fields along the western offshore produce 16 million tonnes per annum of oil, which is 44 per cent of India's total crude oil production of 36 million tonne.

ONGC produced 25.5 million tonnes of oil in 2016-17, which will reach 28-29 million tonnes by 2019-20, the official said. He added that the company has successfully reversed the flagging output at its western offshore fields as it strategically struck "low-hanging fruits''. This included completing three sub-sea wells at the Mumbai High field and using innovative technology.