The big-spending Blues, who just missed out on Champions League qualification last season, are reported to be ready to bolster their keeping ranks with the highly-rated 17-year-old as first choice Shay Given recovers from the shoulder injury which ruled him out of the end of the campaign.
A deal is said to have been agreed with Colombian club Boyaca Chico, which will see Bonilla spend time on loan in Spain to help adapt to European football. "The only thing that is left to do is my medical tests and sign the contract," Bonilla told Colombian newspaper Futbolred.
"Besides the fact that I may be loaned to another team, this is a very important door that gets opened for my career, so I will have to start to take English lessons very soon.
"This is a very important step forward in my career, everything has been arranged and according to what the president, Eduardo Pimental, has said to me the transfer has been confirmed."
City have yet to decide whether back-up keeper Joe Hart, who was an unused member of England's World Cup squad, will return to Eastlands or go on loan again as he did last season at Birmingham.
James Milner, who did play a part in the Three Lions' poor campaign in South Africa, is another target in a ¦pound;25million move from Aston Villa, while Ivory Coast midfielder Yaya Toure is expected to seal his switch from Barcelona later this week.
Valencia winger David Silva has also been linked with City, who have already signed German international defender Jerome Boateng from Hamburg.