Cairn India will invest $3.8 billion in three blocks out of its 25 discoveries in Rajasthan, more than double the previously approved cost of $1.5 billion.
The development cost of the Mangala, Bhagyam and Aishwariya fields is proposed at $2.9 billion, against previously approved $1.5 billion.
Another $940 million would be invested in laying a heated pipeline from Barmer to the Gujarat coast, said an official of ONGC, which has a 30 per cent stake in the Rajsthan fields.
When the $1.5 billion cost was approved in 2005, the peak production was estimated at 1,25,000 barrels a day, which in the revised figure has gone up to 1,75,000 barrels per day, he said, adding there has been an increase in the cost of equipment, facility, drilling and manpower.