Elaine Maslin, 21st June 2012
The safety chief of oil group Total said yesterday that lessons will be learned by it and other companies following its major North Sea gas leak earlier this year.
David Hainsworth, Total UK health and safety manager, said more North Sea fields could have similar issues to the one it had to deal with in March when gas started spewing uncontrolled out of its Elgin platform.
He said the design of the well, 150 miles off Aberdeen, had not been created to deal with the issue that occurred – gas and condensate, a paraffin-like substance, leaked into part of the well deep beneath the seabed from a reservoir the firm had not been tapping.
That issue was then compounded when a process to stop the gas leaking in saw a failure in the well up on the platform, letting the gas spew out into the atmosphere.
“There are lessons to be learned,” said Mr Hainsworth, who was speaking at the Step Change in Safety Share Fair at Aberdeen Exhibition and Conference Centre, attended by just over 300 delegates compared to 180 last year.
“We have to adapt some procedures and we will have to resubmit the safety case prior to any restart of production,” he said. “We are keen when the investigation is complete to share it with the industry.
“There are other operators out there with similar fields and we will be talking to them. They are keen to understand what we have got and we are keen to share it with them.”
Mr Hainsworth also gave an update on what Total was doing on Elgin.
He said investigations internally and by the authorities were ongoing and work to ready the well head platform, where the leak occurred, and the Rowan Viking drilling rig, for a process to cement the well shut was also ongoing.
He said: “At the moment 135 people are living on the Elgin PUQ (accommodation and process facilities deck). We will not fully reman the Rowan Viking drilling rig until we cement plug the well.”
He said work cleaning up the well head platform, where the leak came out, was still being carried out. The next stage would be making sure pumps on the Rowan Viking to pump cement into the well work.
Several cement plugs will be set, he said, covering a section of well about 229ft deep.
“There is work to do on the wells,” he said. “We are going to move a rug to the Franklin platform to do an assessment on the wells there.
“Work is continuing on a relief well, but would soon be suspended due to progress on the top kill operation – although the rig will remain in place as a precaution.”
At the moment it is understood the initial issue was pressure in the well, thought to be from ingress of gas and condensate from a non-producing reservoir above where the producing reservoir had been plugged.
This somehow leaked between different levels of well casing. To stop this leak the firm was carrying out a top kill operation, to hold down the leaking gas and liquids.
But something during that process failed which meant there was a leak into an outer piece of casing, which should have released the pressure into an area of reservoir, like a safety valve, but instead leaked out of the well at the top on the platform.
“It is not necessarily a high pressure high temperature issue,” said Mr Hainsworth. “The issue is when you have a formation that could potentially challenge the casing in your wells.
“The rules are around stopping releases coming out of production tubing – not stopping something coming in.
“It is designed to release into the open formation but something failed so it released on the well.
“We need to adapt perhaps how we work with the wells and some of the safety measures in place.”