The defender joined Die Konigsblauen on a season-long deal in August 2016 but saw his spell cut short by a serious knee injury which has kept him out for the last year.
With his Chelsea future looking bleak, a return to the Bundesliga, where the Ghanaian also played for Augsburg, has been mooted.
Schalke have been mentioned as an option and Heidel says the clubs have spoken and a deal could be on the cards.
He told his club’s official Twitter site: “We’re in talks with Chelsea regarding Baba Rahman. There are still one or two things to clear up on their end.
“We could agree on a deal with the player himself relatively quickly.”
Colchester will hand late fitness tests to Ryan Jackson and Brandon Comley prior to their clash with Yeovil.
Arsenal secured their place in the quarter-finals of the Europa League following their 3-1 defeat of AC Milan at the Emirates Stadium on Thursday.
Danny Welbeck scored twice against AC Milan to toast his England recall by sending Arsenal into the last eight of the Europa League.
Ipswich striker Joe Garner will not play again this season after it emerged he suffered a fractured skull against Sheffield United last week.