Operations resumed at Iraq's southern Nassiriya oilfield on Monday, two oil sources said, but it will take up to two days for output to be fully restored.
Protesters broke into the oilfield, which produces 80,000-85,000 barrels of oil per day, on Saturday and forced employees to cut off electricity from its control station, taking it offline.
The incident marked the first time protesters have shut an entire oilfield, though they have blocked entrances to refineries and ports in the past.
It did not affect Iraq's exports, the oil ministry said on Sunday, adding it would use additional output from southern oilfields in Basra to make up for the missing shipments.
Mass protests have gripped Iraq since Oct. 1 and protesters, most of them young, are demanding an overhaul of a political system they see as corrupt and keeping most Iraqis in poverty.
More than 450 people have been killed.
Protesters are demanding the appointment of a premier with no party affiliation and the removal of the entire ruling elite seen as enriching itself off the state and serving foreign powers — above all Iran — as many Iraqis languish in poverty without jobs, healthcare or education.