The deceased and injured workers were part of a maintenance crew, including security and environmental officials. They were working on repairs Thursday on the Tebidaba-Clough Creek line near the town of Azuzuama in the Niger delta’s Bayelsa state.
Reportedly, bodies were seen floating on the river as the search for casualties continued.
The cause of the explosion is still being investigated according to Iniro Wills, state commissioner for the ministry of the environment. One of Wills staff is still missing.
"Three victims rescued are now at the hospital. Two were severely burnt," Wills said.
Eni has a joint venture with Nigeria's state oil company, and has committed to expand its footprint in the Nigerian oil and gas sector despite political and safety concerns.
The company and authorities will continue the investigation, examining what caused the deadly explosion.