Workers at Brazil's Oil & Gas giant Petróleo Brasileiro S.A. (NYSE:PBR), aka Petrobras, have announced a nationwide strike starting December 15, terming the company's latest counteroffer for a labor agreement as "disrespectful”. Petrobras workers have been pushing for changes to the employee compensation structure, claiming there’s a deficit in the retirement fund. However, Reuters cited an unnamed source as saying that contingencies have been put in place, with the strike unlikely to affect operations or production. …