The 21-year-old arrived at Stamford Bridge 18 months ago from Barcelona and it was thought at the time that Chelsea had snapped up a star of the future.
However despite a bright start to his Chelsea career under former boss Andre Villas-Boas, things have not gone to plan since and he has struggled for opportunities after Roberto Di Matteo took charge.
Romeu has been linked with a loan move to the Championship with Bolton known to be keen but a return to La Liga looks the most likely option with both Espanyol and Valencia keen.
The player's agent had opened talks with Valencia over a move and they looked favourites to do a deal before Espanyol entered the running.
Romeu would prefer to return to the Barcelona club and a deal could be hammered out before the transfer window re-opens in January.