It was not immediately clear if production had been affected.
In a statement, the ministry said the fire broke out at the Priobsky field in the western Siberian region of Khanty-Mansiisk.
The fire broke out in a furnace used to evaporate water from crude oil, it said.
The statement said the fire covered an area of 300 square metres, and that 16 oilfield staff had to be evacuated. It said 76 fire-fighters and 17 fire service vehicles were despatched to the scene.