The deal will go ahead provided the 23-year-old, capped 16 times caps and who played in the World Cup finals, passes a medical.
"Benfica has reached agreement in principle with Chelsea for the transfer of Ramires for a fee of 22 million euros," read the Benfica statement.
"The agreement will be finalised once the player undergoes medical examinations."
Ramires joined Benfica at the beginning of last season from Brazilian side Cruzeiro on a three year contract.
The transfer has a complication in that Benfica have a 50 percent stake in the player with the other 50 percent owned by a British-based businessman.
To tie-up the deal Chelsea would have to come to an agreement to comply with Premier League regulations that outlaw the third-party ownership of players.
Source: AFP Global Edition