UPDATE 3-Shell, Repsol register for Iraqi oil deals-sources

(Adds Exxon details, paragraphs 8-10)

By Simon Webb

DUBAI, Feb 6 (Reuters) - Oil major Royal Dutch Shell (RDSa.L: Quote, Profile, Research) and Spanish energy company Repsol YPF (REP.MC: Quote, Profile, Research) have both registered to compete for contracts to develop Iraq's huge oil reserves, company sources said on Wednesday.

Big oil firms have been positioning themselves for years to gain access to the world's third-largest reserves, among the cheapest oil to produce in the world.

Iraq has given companies until Feb. 18 to submit documents that will qualify them to compete in tenders for service contracts to help develop its oil infrastructure. The deadline was extended from Jan. 31.

"Shell has submitted its prequalification documents, as per the original deadline," a Shell company source said.

A spokesman for Repsol in Madrid confirmed that Repsol had also submitted its documents.

Shell and Repsol join BP (BP.L: Quote, Profile, Research) on the register. BP chief Executive Tony Hayward said on Tuesday that his company had signed up.

BP has no plans to send personnel into Iraq until the security situation improves, but would be interested in service agreements and cooperation with the country, a BP spokesman said on Wednesday.