Santos spent the past two years away on-loan before being brought back for this term.
The youngster has impressed when called on and he told the club's website: "This season is my first season at Chelsea, and I’m so happy to be here,’ Andrey opened. ‘The Premier League is so different from Ligue 1, but I have my team-mates, the coach and the staff from Chelsea who are helping me a lot. I like experiencing this challenge.
"The intensity in France is top, but in England it is a different kind. It’s 90 minutes, and if you lose one ball, it can lead to a goal. So, you have other be ready all the time.
"The coach always says to us to be ready because we have a lot of matches in a lot of competitions like the Premier League, the Champions League, the Carabao Cup and soon the FA Cup. So, I think it’s important to be ready so that when the opportunities come, I can give my best."
On going to Newcastle today and facing their Brazilian captain Bruno Guimaraes, Santos continued: "Bruno is a top player.
"I like him because I think we have similar qualities. He scores goals, assists and defends well, and I try to do this too.
"When I was playing for Vasco da Gama, he sent me a message saying he was happy for me because he is a Vasco supporter. So, I think our relationship is really good."