New Delhi, May 19 (PTI): Oil and Natural Gas Corporation Ltd (ONGC) is likely to see oil and gas production from its largest fields in Mumbai offshore fall by 2012 as natural decline sets in the 20-year-old fields.

Crude oil production from the Mumbai High field is slated to dip to 10.362 million tonnes in 2011-12 from 12.108 million tonnes in 2007-08, a company official said.

Mumbai High, which contributed 45 per cent to ONGC’s 25.94 million tonnes crude oil production in 2007-08, is likely to produce 12.354 million tonnes this year before decline sets in.

ONGC’s total crude oil output this fiscal will be higher at 27.054 million tonnes with the company bringing to production new and marginal fields.

It will rise to 29 million tonnes next fiscal before dipping to 27.36 million tonnes in 2011-12.

Gas production from Bassein and its satellite fields will dip to 5,040 million standard cubic metres (about 13.8 million standard cubic metres per day) in 2011-12 from 10,129 million standard cubic metres (27.5 mmscmd) in 2007-08, he said.

As a result of natural phenomenon, reservoir pressure at the gas field has declined with continuous production for over 20 years.