The home side dominated the early proceedings as they took the game to St Mirren and could have opened the scoring as early as the 11th minute but Paul Quinn could only side-foot David Clarkson's lay off wide.
Three minutes later Saints almost set up Well themselves with some comical defending.
Franco Miranda was short with a pass back and Chris Smith compounded this when he played the ball straight to Ross McCormack. The keeper recovered well to make a fine stop from the striker's shot.
Motherwell continued to push forward and Chris Porter was unlucky to see a header fly over at the near post.
However, the big striker did break the deadlock on 29 minutes following some excellent build-up work.
Jim Paterson took a quick throw in to Phil O'Donnell who planed a one-two with Clarkson before crossing for Porter to fire home at the front post.
The visitors had little to offer in front of goal throughout the opening 45 minutes until they scored with their first real effort in stoppage time.
An Alex Burke corner was swung to the far post where Billy Mehmet's header seemed to pose little threat until Stewart Kean appeared from nowhere to head past Graeme Smith.
Both sides were committed to attack at the start of the second period and the only surprise was it took almost 15 minutes for a keeper to be called into action.
Clarkson found space in the St Mirren 18-yard box and fired in a right-foot shot which Smith saved one-handed and diving to his right.
Minutes later Clarkson was once again denied by Chris Smith who made another diving save to keep out the striker's header.
With five minutes left the visitors should have taken the lead when Mark Corcoran burst past Stephen Craigan on the left and his cross was perfect for Mehmet, but the striker could only hit the underside of the bar from close range.
A draw was fair over the 90 minutes with Motherwell the better side in the first half and Saints the stronger in the second.