The Arabia-4 barge sank on Friday on the Safaniya field, with the bodies of two Indians and one Bangladeshi found the following day, operator Aramco said.
Earlier reports had identified the sunken unit as a rig.
“Response teams were immediately mobilised to the incident scene supported by helicopters, as well as specialised diving and medical evacuation teams,” Aramco said in a statement.
“Rescue efforts continued until the entire crew had been accounted for, with the bodies of the three deceased recovered and handed over to the concerned authorities.”
Some of the rescued workers had suffered minor injuries.
“The condition of all injured persons is stable, and a specialised team is investigating the incident,” Aramco said.
The cause of the sinking is not known but state-owned oil giant Aramco said production had not been affected.