The corporation disclosed this in a statement signed by its spokesman Dr Kennie Obateru, in Abuja on Wednesday.
NPDC operates the OML on behalf of the NPDC/Elcrest Joint Venture.
He said the incident, which occurred on Tuesday during the installation of a ladder on a platform (Benin River Valve Station) for access during discharging of Gbetiokun production, unfortunately caused seven fatalities.
He added that investigation on the cause of the explosion had commenced, while the Department of Petroleum Resources had been duly notified and Form 41 was being prepared for the industry regulator as required in circumstances of this nature.
“The bodies of casualties have been deposited in a morgue in Sapele, while families of the personnel involved are being contacted by their employers: Weld Affairs and Flow Impact, which are consultants to NPDC,” he said.
He noted that all personnel on board the platform had been fully accounted for adding that the NNPC Group Managing Director, Malam Mele Kyari, had commiserated with the families of the bereaved.
He noted that Kyari prayed that God grant them the fortitude to bear the irreparable loss of their loved ones.