Royal Dutch/Shell Group is losing 80,000 barrels of oil per day since the start of a protest by Nigerian youths from the Ijaw ethnic group on Friday, company spokesman Bisi Ojediran said.
Ojediran said production has been cut off at six pumping stations in the Niger Delta by the protests.
The Ijaw are angry at the distribution of council wards near the town of Warri in Delta State and have vented their frustration on the dominant local industry.
Shell has opened talks with the Delta State government and Ijaw representatives to resolve the situation, Ojediran said.
Company officials said workers have been evacuated from the flowstations to ensure their safety.