Brazilian state-run oil company Petroleo Brasileiro SA’s long history of failed spending and output plans may be the biggest obstacle to its efforts to convince investors it will reduce its massive debt. The company’s $90 billion cut on Monday from planned investment over five years and 30 percent reduction to its 2020 oil and natural gas output forecast mark the first major retrenchment by Petrobras, as it is known, since the discovery of giant offshore oil reserves south of Rio de Janeiro was announced in late 2007.