The Nigerian striker, who topped the scoring chart with 26 goals, converted a 29th minute spot kick and went on to pump in one more at the break.
New Zealand recruit Kayne Vincent's header in the 57th minute sealed the issue for the purple brigade while Lalmuanpuia reduced the margin with a freekick in the 70th minute for ONGC.
United SC finished with a tally 44 points behind third-placed East Bengal while ONGC remained on 31 points.
ONGC had another fine attack through an Eric Brown left-footer in the 14th minute but Paul once again stood tall under the bar.
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In the 28th minute, Vincent was brought down inside the box by Odeola as a penalty was awarded to the home team with Martins making no mistake.
In the first-half added time, Martins added one more when he beat the offside trap for his second goal.
Deepak Mondal set it up for Vincent with a fine cross as the New Zelander comfortably nudged it home.