Missouri limited Nicholls State to 19 field goals while improving to 3-0.
Oriakhi had 17 points and 10 rebounds while Earnest Ross scored 16, Keion Bell 13 and Laurence Bowers 12.
The Tigers owned a 32-25 lead at halftime, then began the second period on a 22-7 run. Missouri won the rebounding battle by 12 and hit 7-of-12 from beyond the 3-point arc.
The Colonels (0-2) got 22 points from Fred Hunter.