The president of the 20-year-old's current club, Internacional, has confirmed a potential move is at a "very advanced" stage amid reports it will be sealed on Friday.
Giovanni Luigi told terra.com.br: "The situation is very advanced, but not finalised yet.
"Oscar has to get his work permit. He needs to have a certain amount of caps to play in England, but I don't believe that will be a problem."
Oscar will play in the UK at the Olympics, which begin this week, and says he has already undergone a medical at Chelsea.
Reports suggest the Blues will pay a £25million fee for him, some of which will go to the player's former club, Sao Paulo.