It's been a strained courtship between Iraq and oil companies jockeying for its untapped riches _ complicated by jitters about insecurity, lack of a legal rule book to govern investments and Baghdad's tightfisted bargaining that turned last summer's much-hyped bidding round into a failure.

Even as the same security and political concerns remain unresolved, they appear ready to give it another go. For the companies, the prize is too big to ignore: 15 fields that represent the largest cut of Iraq's oil wealth available to outside companies in decades. For Iraq, it means access to technical expertise and hard cash, with oil sales accounting for 95 percent of its budget.

A successful auction this time could set the tone for future deals as Iraq opens up the world's third-largest oil reserves to companies for whom cheap oil is becoming increasingly a thing of the past.

"The volumes," Samuel Ciszuk, an oil expert with London-based consultancy IHS Global Insight, said, summing up simply the incentive for the companies despite the political uncertainties and the security risks.

"It's the huge volumes involved and access to the oil flows."

A total of 44 companies will make their pitch this week, vying for the 15 fields _ the largest of the reserves located in Iraq's relatively calm Shiite-dominated south.

They include giants Exxon Mobil Corp., Britain's BP Group PLC, Chevron, ConocoPhillips and Total SA, as well as a range of state-backed companies from countries such as Russia, Angola, India and Kazakhstan.

While they represent the best _ if not only _ option for Iraq's hope to rebuild an oil sector suffering alternately from decades of neglect, war and sabotage, what remains to be seen is whether these firms are willing to accept less lucrative contract provisions to stake their claim to a piece of the Middle East's last major oil and gas bonanza.

"Iraq has huge oil and gas reserves and all the world companies are interested in having even a small piece of the cake," said Kamel A. al-Harami, an independent oil analyst based in Kuwait and former president of Q8, the retail arm of the Kuwait Petroleum Co.

"I do not think that security fears would play a major role in the decisions of the oil companies."

But extra precautions will certainly be on display after Tuesday's wave of deadly bombings that targeted government offices for the third time since August.

The last bidding round was held at a hotel in the Iraqi-guarded Green Zone. Friday's event was moved to the Oil Ministry building, which is under even tighter protection.