The 18-year-old joined the Blues last summer from his boyhood club Sao Paulo for an undisclosed fee.
"When I came there were three Brazilians already here and when Oscar came there were three as well and I think it was good for him, how it was for me," Piazon told the club's official website.
"It helps you to adapt and to get closer to the people in the club and that is really important. We are always together, in each other's houses, in David's house, in Rami's house, and it is good to be like this."
Piazon has made one senior appearance for the club.