All three players participated in this week's full-squad minicamp on a tryout basis.
To make room on their roster, the Bears waived a pair of undrafted rookies, defensive lineman Thomas Schaffer and tackle Gunnar Vogel.
Pennel has appeared in 91 NFL games with 16 starts over seven seasons with the Packers (2014-16), Jets (2017-18) and Chiefs (2019-20). The 6-4, 332-pounder has registered 155 tackles, 2.0 sacks and 8.0 tackles-for-loss. Last season he played in 14 games with one start for Kansas City, recording 29 tackles.
Butt was selected by the Broncos in the fifth round of the 2017 draft out of Michigan. He was being projected as a second-round selection before sustaining a torn ACL in his final college game with the Wolverines. Injuries limited the 6-6, 250-pounder to just eight games in four seasons with the Broncos.
Wheatley played tight end at Michigan and Stony Brook before switching to tackle this year while participating in The Spring League, a developmental league for NFL hopefuls. He's the son of former Michigan star running back Tyrone Wheatley, who played 10 NFL seasons with the Giants (1995-98) and Raiders (1999-2004).
Check out the action from Halas Hall as the Bears hit the practice fields during their full-squad minicamp.