India's Oil and Natural Gas Corp expects crude output to rise 15 per cent to 600,000 barrels per day in 2006-07 but production from its ageing fields will fall rapidly in subsequent years, a company official said.

The company is spending Rs 8,200 crore (Rs 82 billion) for enhanced oil recovery projects to boost output in the next four years, but higher production can be sustained only with new discoveries, he said.

It has estimated that by 2015, its output would be half its current production of 520,000 bpd but ONGC hopes to find more fields in India and acquire equity oil abroad.

"Production from our existing fields will decline after 2006-07 but we expect more discoveries especially in deep water blocks," the official, who did not want to be identified, told Reuters.

He said the company was assessing the commercial viability of some recent discoveries, including a field that has an estimated 30 million tonnes or 222 million barrels of oil reserves.

The state-run firm is also aggressively scouting for equity oil abroad to meet the energy needs of India, which imports 70 per cent of its crude oil requirement.

ONGC recently bought a 25 per cent stake in Sudan's 250,000-bpd Greater Nile Project.

It already has a 20 per cent stake in Russia's Sakhalin-1 project as well as a 45 per cent stake in a gas field in Vietnam.

India's petroleum secretary B K Chaturvedi said last month that India should spend $1 billion a year for at least a decade to secure oil and gas reserves abroad.