An empty bullet shell is seen outside the entrance of the al-Ghani oil field, belonging to Libya's Harouge Oil Operations company, near the city of Waddan in the central Al-Jufrah province on March 23, 2013. Libya plans to invite bids from foreign firms for oil concessions by the end of 2013 as Tripoli wants to increase its OPEC output quota despite conflict with armed militias, strikes and allegations of corruption.