Logan McVeigh, Carson Perreaux, Mark McNeill and Josh Morrisey had the goals as Prince Albert (4-0-1) won its fourth in a row.
Travis Ewanyk replied for Edmonton (3-2-0), which lost to Prince Albert at home in regulation for the first time in five years.
Tristan Jarry stopped 17 shots in taking the loss.
McVeigh opened up the scoring 9:23 into the first on a one-timer to give Prince Albert the early lead.
Perreaux doubled the lead for Prince Albert halfway through the second, deflecting in a feed from the side boards by Shane Danyluk.
Siemens stopped Edmonton's Klarc Wilson with a breakaway glove save early in the second, then stood his ground on the goal-line later in the period.
Ewanyk pulled the Oil Kings within one on a power play early in the third, but McNeill restored the two-goal margin with a sharp-angle shot less than three minutes later.
Morrissey then added a short-handed empty net goal.
McNeill has points in all five games this season for Prince Albert, and leads the club in scoring with three goals and four assists.
The Raiders have now held the lead against opposition clubs so far this season for 176 minutes 57 seconds, while trailing for just 4:02.