The Belgium goalkeeper's contract expires in June 2019 and he has been linked with a move to Real Madrid amongst others but he says he has no intention of moving on.
Courtois also says "irreplaceable" compatriot Eden Hazard is eager to extend his stay at Stamford Bridge as well, the Belgium international's deal runs until 2020.
"I'm happy at Chelsea and a deal is close," Courtois said in the London Evening Standard.
"Has it been a distraction? Not for me. I'm just calm and relaxed because I'm tied to Chelsea.
"Despite the rumours and everything, I am focused on Chelsea and I'm happy here.
"Do Eden and I encourage each other to sign? Yes. He will say 'if you sign, I will sign' and I say the same to him.
"I think we are both happy at Chelsea, we both have a good part to play. We have been champions twice in the four seasons I have been here and can have our peak years together at Chelsea."