Iran could mark its return to the global energy stage when, perhaps by the end of the year, it starts $185 billion worth of new projects, OPEC said.

The Organization of Petroleum Exporting Countries said in a monthly newsletter it's expecting Iran to bring new projects online as sanctions pressure eases. Iran, which is a member of OPEC, has been preparing for the day when sanctions are released and international oil companies again express interest in investing in the country.

"Iran has drawn up a list of some 50 oil and gas projects worth $185 billion which it intends to start developing once longstanding economic sanctions against the country are lifted, most likely later this year, or early in 2016," the 12-member group said.

Iran, the five permanent members of the U.N. Security Council, plus Germany, reached a breakthrough agreement in July that curtails nuclear research activity in exchange for economic concessions. OPEC said members of the European Union have already approved the deal, a key step toward lifting European sanctions.

Iran may need significant foreign investments as sanctions kept most major companies out of the country. European energy companies from Royal Dutch Shell to Italy's Eni already have sent representatives to Tehran in recent weeks to test the investment climate.

The government said there's been little domestic capital invested in the national oil sector under sanctions.

Crude oil production from Iran in July was around 3.1 million barrels per day, compared with a pre-sanctions level of around 3.6 million bpd. Crude oil exports, meanwhile, are limited to around 1 million barrels per day and to six nations under the terms of existing sanctions.

Iran in December presents new contract terms at an investment conference in London.

The July nuclear agreement has yet to be approved by the U.S. Congress.