The 32-year-old Spaniard has been at the club's Rockliffe Park training headquarters for much of this week as he attempts to tie up a deal after being released by Osasuna.
Karanka is confident matters will be concluded on Friday in order for Abella to line up in the Sky Bet Championship at Elland Road, and is already turning his attention to formalising a season-long loan deal for Chelsea striker Patrick Bamford.
He told the Northern Echo: "Damia's signing should be done in time for Saturday, and if everything is done, I think he will have his chance.
"I would like to do a couple of changes again. The deal is practically done, it is just the last details we are going through now.
"Bamford is one of the names we are working on. The club knows the players who I want, and they are working on bringing them on their way."
The Spaniard is confident the players he has at his disposal will score goals, but his aim is to ally that with a miserly approach at the back to lay the foundations for success.
Karanka told the Northern Echo: "The defence is very important because, in Spain, we say you have to build a house from the floor.
"The most important thing to win games is not to be conceding goals. If you have a squad with players with quality, you are always going to score goals.
"With the players we have here, I know we can score, so if you don't concede many goals either, you should be successful."