BAGHDAD, Aug. 14 (UPI) -- International oil firms are taking steps to ready for bids on Iraq's vast oil reserves, hopes pinned on Iraq's Parliament approving a law governing the oil.

Last week Chevron and Total agreed to cooperate on Iraq bids, hoping to get a piece of a large pot of crude. Iraq has 115 billion barrels of proven reserves, most of which are not being pumped now. The country is underexplored and experts say modern exploration could prove reserves are double current counts.

Lukoil, the major Russian firm, is trying to win back a contract signed and then dissolved During Saddam Hussein's regime, teaming up with Russian state-owned firms and asking the government to help its case.

ConocoPhillips, which owns 20 percent of Lukoil, is also helping out.

Royal Dutch Shell and BHP Billiton (NYSE:BHP), of Australia, are researching the Missan area of Iraq, Business Intelligence Middle East reports. Shell and Mitsubishi are eyeing plans for Iraq's vast natural gas deposits as well.

The China National Petroleum Corp. already received a pledge from Iraq's oil minister to renegotiate a contract signed under Saddam for the al-Ahdab oil field. Any deals that were valid at the time of the regime's fall will be upheld, though they need to be brought in line with a future federal oil law.

That law is stuck in negotiations between political factions. They can't agree on how much power the central, federal and local governments each should have in exploration, development and production of the oil. Also at issue is a key decision as to what extent foreign companies will be allowed to invest in the sector.