Gabon signs offshore oil contracts with six companies

(Adds context in paras 2-3, background on negotiations)

LIBREVILLE, Aug 8 (Reuters) - Gabon's oil ministry said on Friday it had signed seven oil contracts with six companies as part of an offshore licensing round expected to attract at least $1.1 billion in investment to the sector.

The Central African country hopes that this tender, its tenth, will help it reverse a chronic decline in output due to maturing onshore fields. The former OPEC member currently pumps about 230,000 barrels per day, down from a peak of close to 400,000 bpd in the 1990s.

Drilling deep offshore the Gulf of Guinea is expensive but potentially very rewarding for oil firms, given the similar geology to oil-rich Brazil, where billions of barrels of oil have been discovered.

The companies that have signed contracts are: Impact, Repsol , Marathon, Noble Energy (NYSE: NBL - news) , Petronas and Woodside.

The deals end over nine months of arduous negotiations in which the list bidders has changed several times.

Two companies - U.S. oil major Exxon Mobil and British oil explorer Ophir - invited in late July to enter a final round of negotiations did not feature on the ministry's final list. Australia's Woodside was not invited to the final round, yet was named as a winner. (Reporting by Gerauds Obangome; Writing by Emma Farge; Editing by Erica Billingham)