A consortium led by oil giant PetroChina has formally signed a 20-year deal with Iraq to develop the Halfaya oil field, as China boosts its presence in the crude-rich region.

PetroChina, France’s Total, Malaysia’s Petronas and Iraq’s South Oil will develop the field in southern Iraq, which has proven reserves of about 4.1 billion barrels, the Chinese company said in a statement late Wednesday.

The companies plan to boost output at Halfaya to 535,000 barrels a day from the current 3,100 barrels, PetroChina said.

PetroChina, the listed arm of China’s top oil and gas producer, state-owned China National Petroleum Corp, will hold a 37.5 percent stake in the joint operation.

Total and Petronas will each hold an 18.75 percent stake and South Oil will have a 25 percent share.

According to an agreement initialled in December, the companies will receive fees of 1.40 dollars per barrel extracted from the site.

Iraq auctioned Halfaya to the consortium on December 11, the first day of a two-day oil field auction that dramatically increased the country’s projected crude production to 12 million barrels per day within seven years.

The Halfaya deal marks the latest contract signed by PetroChina in Iraq.

Last year, the Chinese firm sealed a deal, along with Britain’s BP, to ramp up production at Iraq’s biggest oil field, Rumaila, and in 2008 it signed a contract to develop the Al-Ahdab oil field, .

China has been investing billions of dollars around the world to secure access to oil and other raw materials needed to fuel its fast-growing economy.