The Norwegian oil operator revealed the conclusion at a press conference earlier today. It follows the completion of an investigation into the incidents at its Mongstad Refinery and a separate incident on the Songa Endurance in the North Sea.

The incident on the Songa Endurance happened on Saturday 15th October during well plugging activities.

The loss of well control led to a gas leak that surged seawater more than 30 metres up the rigs derrick before the Annular Blowout Preventer was activated to seal the well.

Statoils report defined the investigation as having a “high degree” of seriousness.

In a statement the firm said: “At worst it could have led to a loss of life if the safety equipment had failed to function as intended, or if the gas had been ignited.

“The BOP was quickly activated and stopped by the gas leak, and five gas detectors automatically turned off equipment that could have produced sparks.”

The investigation report concluded that two main findings have weakened the barriers and helped gas reach the drill floor.

Margareth Øvrum, executive vice president for technology, projects and drilling in Statoil, said: “This is a very serious well control incident. The actions taken will improve our ability to

assess risk, both before and during operations. We will share our experience from this incident with the rest of the industry.”

It was found during surface maintenance on Tuesday, October 25th, a hydrogen leak had occurred at the Mongstad refinery.

It was found to have occurred due to external corrosion of a pipe socket at the processing complex.

Statoil said: “During pipe inspection in connection with surface maintenance in the isomerization plant at Mongstad, a portable gas detector was triggered close to a valve.

“When an attempt was made to close the valve, the pipe socket broke and high-pressure hydrogen-rich gas was released.

“During pipe inspection in connection with surface maintenance in the isomerization plant at Mongstad, a portable gas detector was triggered close to a valve.

“When an attempt was made to close the valve, the pipe socket broke and high-pressure hydrogen-rich gas was released.”

Statoil have now decided to intensify its programme surface maintenance over the next two years.

Jens Økland, executive vice president for Marketing, Midstream and Processing (MMP) of Statoil, said: “We are intensifying the activity to handle risk related to corrosion under insulation at Mongstad.

“In addition, we are implementing measures to improve interaction and involvement in connection with maintenance and any findings. The threshold must be low for asking risk-related questions and implementing required measures.”