The windfall is courtesy the Oil Ministry, which changed the pricing of domestically produced natural gas from rupee to the US dollar last year, industry sources said.
In May last year, the ministry had decided that gas produced by ONGC and Oil India should be priced in US dollars when rates were revised to $3.818 per million British thermal units ($4.2 per mmBtu after including royalty) from Rs 3,200 per thousand cubic metres (equivalent to $1.79 per mmBtu).