Petrobras (PBR +0.2%) is experiencing serious problems, as its oil production has stagnated, its employees have been accused of taking bribes, and its debt is surging, according to a NYT profile of the company.Analysts warn that the company could face problems in international bond markets: As U.S. interest rates creep up and as Brazil’s finances come under greater stress, PBR’s top creditors - which include mutual fund giants like Pimco, Fidelity and BlackRock - may view their exposure as too risky and begin to unload their bonds."We are just waiting for this thing to blow up,” says one emerging market investment consultant who worries that a PBR selloff could ignite a broader emerging market pullback.