Chinese firms CNOOC and CNPC, Royal Dutch Shell and France\'s Total joined Brazilian state operator Petrobras in a joint bid to win Monday\'s auction to develop the huge Libra oilfield. The four energy giants won 35-year concessions, with Petrobras taking a 40 percent stake. Shell and Total both earned a 20 percent stake, with CNOOC and CNPC securing 10 percent each.