Oil and Natural Gas Corp aims to invest 1 trillion rupees ($10.51 billion) over five ‌years ⁠for exploring ⁠its local deepwater and ultradeep water fields, Chairman AK Singh said on Monday.ONGC will drill 87 deepwater and ⁠ultradeep water ‌wells by March 2031, he said ⁠during a news conference.India has huge untapped reserves of oil and gas in deepwater blocks, and there are now technologies available ‌to tap those resources, Singh said.ONGC needs major discoveries to ⁠arrest the decline in its oil and gas output.