Stuart Anderson and Bryan Novoa share third place at 7-under-par 135. Brett Carman, who held a piece of the first-round lead, was one shot further back along with Anders Hultman and Robert Hamilton at 6-under-par 136.
Compton, a two-time winner on the Canadian Tour, jumped out of the gate on the back side with back-to-back birdies starting at the par-4 10th. He parred his next seven holes before starting the front nine with two consecutive birdies from the first.
The 24-year-old parred the third but picked up a birdie at the par-3 fourth. Compton then made it two in a row again with a birdie at the fifth to take a two-shot advantage into the weekend at Mayfair Lakes.
Heffernan also started on the 10th and collected three birdies over his first nine holes to make the turn at 5 under.
The 27-year-old from Calgary tallied an eagle at the par-5 fifth and added a birdie at the eighth to complete a 65 of his own.
Rob McMillan, Stephen Woodard and David Mathis are knotted at 5-under-par 137.
The 36-hole cut fell at 1-over-par 143 with 66 players qualifying for the weekend. Last year's champion James Lepp came up short after a 4-over 75 left him at 6-over-par 148. Chris Baryla, who shared the opening-round lead with Carman, also missed the cut.