Oil and Natural Gas Corp (ONGC) today approved an investment of Rs 2,300 crore for re-development of its ageing Heera and South Heera fields at Mumbai offshore in the Arabian Sea.The re-development will enhance production with improved recovery and redistribution of water injection, pattern sweep and pressure maintenance.The project includes development of a marginal field B-134 A through Heera facilities, which would not have become viable for exploitation on stand-alone basis. ONGC, recently received approvals from regulator DG of Hydrocarbons, for redeveloping its Heera oilfield. The estimated incremental gain is estimated at 10.685 million metric tonnes (MMT) of crude oil and 2.265 bn cubic metres (BCM) of natural gas by 2030. ONGC's output has stagnated at about 520,000 barrels per day in recent years and fell to 490,000 barrels per day in the full year to March 2006, after an accident destroyed an offshore oil platform in July 2005.The oil major recently said it plans to spend Rs 60,000 crore during 2007-12 to raise its total production to 140 mn tonne.