Oil prices failed to break out on Friday, as traders showed themselves cautious, voicing concerns about global economic growth.  Oil prices have been flat for several days, weighed down by concerns about the health of the global economy, plus the potential return of supply from Libya. “Growing economic concerns, falling stock markets and emerging doubts that the trade conflict between the US and China will be resolved are putting oil prices under pressure,” Commerzbank wrote in a note on Friday. Russia throws a lifeline to Venezuela . U.S. sanctions on Venezuela threaten to shut in a major portion of the country’s oil production. Not only do sanctions bar Venezuelan oil from flowing to the U.S., but crucially, it also prohibits U.S. diluents from […]