A goal just before half-time keeps the Saints at the top of the table, just one point ahead of title rivals Dundalk
After a slow start, with neither side making inroads, the Saints had a penalty shout turned down when Killian Brennan went down in the area. At the other end, Shels' first chance fell to Glenn Cronin, but the midfielder's rising effort went just past the post.
Brendan Clarke pulled off an excellent save to keep the game scoreless, denying Dean Kelly after Stephen Hurley's centre. Pat's finally had a proper opportunity five minutes before half-time, and took the lead thanks to Stephen Maher who put the ball past Niall Burdon, who had come off his line to make a clearance. Burdon was beaten again just before half-time, but watched Anto Flood's chip go narrowly over.
Maher had a good chance to double his tally after good interplay with Chris Forrester, but was denied by Burdon before putting his second attempt off target. The Saints looked the most likely to score with Forrester and Christy Fagan going close, but Shels battled on, and almost carved out a chance for Derek Doyle with 20 minutes remaining.
Conan Byrne went even closer five minutes later, but could not add to his tally for the season after bagging four in his last outing. Burdon denied Ger O'Brien and Killian Brennan late on as the Saints eased to victory.
The win keeps St Pat's a point clear of Dundalk at the top of the table, but Liam Buckley's side still have a game in hand over their title rivals.