Public sector ONGC on Saturday said it has achieved highest reserve accretion of the decade and would invest Rs 3,570.6 crore for maintaining, revamping and enhancing its oil and gas production from existing fields. The board of the company has approved investment proposals aggregating Rs 3,570.6 crore for maintaining, revamping and enhancing oil and gas production from existing fields. The approved outlay includes ONGC's share of cost of development of Cairn operated oil blocks in Rajasthan. At its 178th board meeting, ONGC also approved an investment of Rs 169 crore for various alternate and renewable energy sources projects, company's CMD R S Sharma told reporters here. Describing the performance as satisfactory, Sharma said ONGC achieved reserve replacement ratio of more than one for the fourth consecutive year. During 2007-08, ONGC recorded in aggregate 63.82 million metric tonne of oil equivalent (mmtoe) ultimate reserves in domestic acreages. ONGC's share of reserve accretion from domestic joint ventures was minus (-) 0.34 mmtoe, while that from overseas operations through OVL was 46.73 mmtoe. The company has made seven new oil and gas discoveries in the country in April, Sharma said, adding that they were not very significant. ONGC will invest Rs 1,804 crore in the development of four fields