The only real chance of an extremely quiet opening 40 minutes came from a free-kick after nine minutes after Jon Stead was fouled on the edge of the box. Albert Adomah stepped up with a right-footed effort that drifted wide of Alex Smithies' goal.
And there was very little to worry the Bristol City backline until two minutes before the break when Lee Novak's cut-back from the left wing was perfectly timed for the onrushing Scannell to mark his return to the starting line-up with a finish past Dean Gerken from six yards out.
The visitors nearly drew level on the stroke of half-time when Cole Skuse's half-volley deflected off Peter Clarke and bounced wide.
There was another good chance shortly after the interval with Gerken forced into a fine save at his near post from Calum Woods.
Smithies had to be at his best just after the hour mark to deny Sam Baldock on the line and keep his side's lead intact after the ball fell to the former West Ham forward.
Winger Adam Hammill had already seen one effort fall just wide before letting rip with a left-footed effort that fizzed over Gerken's crossbar on 68 minutes.
Ryan Taylor and Martyn Woolford were then introduced as Derek McInnes' men searched for a goal to end their miserable run of defeats.
Their next opportunity came from the right foot of Woolford, who tried his luck from the edge of the box but his rising effort went over the bar as City continued to press.
Woolford then produced a lovely inviting ball across the box which was inches away from connecting with Baldock in added time and then in the final move of the match Stephen McManus looked to have grabbed a dramatic leveller but Smithies, at full stretch, got a hand to the Scot's effort.