Iraq has named 35 foreign energy firms who are entitled to apply for contracts to develop the country's potentially lucrative oil and gas industries.
BP, Shell, ExxonMobil, Total, Petronas and China's CNOOC are among those firms seeking deals to extract and pump oil.
Oil sales account for nearly 85% of Iraq's total revenue, but its infrastructure has been damaged by years of sanctions, war and violence.
Daily oil output is now at a four-year high of about 2.3 million barrels.
Improved security in central Iraq has boosted production levels in recent months, although pipelines and oil refineries are still subject to regular attacks.
The US official charged with monitoring how funds are spent in the reconstruction effort in Iraq said in January that the country could reap an extra $15bn from oil sales if it received more investment and clamped down on corruption.
Of the 120 companies which initially expressed interest in the licensing auction, Iraq's oil ministry has shortlisted 35 businesses.
Other prominent firms to make it onto the list include Russia's Lukoil and Norway's Statoil.
Attempts to create a legal framework for how Iraq's oil wealth should be distributed among its different ethnic groups have been beset by problems.
Companies already doing business in the autonomous Kurdish region of Northern Iraq are effectively barred from the auction.