Both were ruled out by club medical staff on Tuesday afternoon.
Wells injured his calf in the first quarter against Essendon and will miss one week.
Grima came off late in the game with hamstring tendonitis and could miss up to two weeks.
Meanwhile Leigh Adams will have a shoulder reconstruction on Friday.
Brad Scott and the North match committee will regain the services of Jack Ziebell and Lindsay Thomas for the Saturday night clash.
