The fire is yet to be contained, according to reports, but sabotage has been ruled out as possible cause of the inferno.
Photographs released by Chevron show the rig, which is operating on the Funiwa field in Block 86, is still engulfed in fire, which cause is yet to be established.
Neither Chevron nor the operators of the rig – Fode Drilling – have given any reason for the blaze, but informed sources suggest there is nothing to suggest any sabotage.
All but two of the 154 workers on the rig and a nearby support barge were evacuated and treated on a nearby platform. They were expected to be taken ashore on Monday evening.
The fate of the two missing crew members, who have not been identified, is unknown.
Chevron reported that the rig is operated by Fode Drilling Nigeria. A spokesperson at the company was unable to comment on the incident, citing a return to work on Tuesday after a week of striking action across the country at the removal of fuel subsidies.
The latest statement on the incident from KS Energy indicates that the rig continues to burn.
Andrew Fawthrop, managing director of Chevron’s Nigeria/Middle East strategic business unit, commented in a company statement on Monday: “Every effort is being made to find the missing workers. They are our utmost priority.
“We do not know what caused the incident. We are working diligently to contain the fire, which is restricted to the rig.
“Substantial resources have been deployed including well control specialists and drilling experts. We continue to work in full cooperation with Nigerian authorities and are committed to providing additional information as it becomes known.”
Chevron has the KS Endeavor on charter for a firm two-year period which started in January 2011. The US oil giant also holds a one-year option over the unit.
Production from Chevron’s North Apoi platform was shut in due to its proximity to the fire.