The ONGC Videsh (OVL), Indian Oil Corporation (IOC) and Oil India (OIL) combine, which has made a huge natural gas discovery in Iran with in-place reserves being estimated at around 10 trillion cubic feet, will get 35% rate of return on the expenditure it made during the exploration phase.OVL had earlier discovered oil in Iran's Farsi offshore block that lies 90-km off Bushehr port. "We have now made a natural gas discovery in the fourth and final commitment well on the block," a top company official said here.The company has 40% stake in the 3,500 sq km block. IOC has a similar stake while OIL holds the remaining 20% stake in the block.Under the contract with the Iranian government, OVL cannot take oil and gas found in the block to India. "We have a service contract under which we are paid a pre-fixed return on the investment we make," the official said.OVL will now present a development plan to the Iranian authorities for bringing to production the oil and gas finds in the block. The rate of return for the development phase is yet to be finalised.