French oil major Total
Operations to inject mud into the well before plugging it are likely to start at the end of next week and last several days, a source close to the matter said.
The reconnaissance mission to the Elgin complex by a team of Total experts and specialist contractors has confirmed that planning for a well intervention operation to bring the leaking G4 well under control can continue as planned, Total said in a statement on Friday.
The leak is spewing an estimated 200,000 cubic metres of natural gas into the air per day, forming a highly explosive cloud around the platform. Workers on the platform were evacuated when the leak was first reported on March 25.
The reconnaissance team of experts was flown in by helicopter and found no presence of gas on the main platform, which houses workers' living quarters, and no gas on the 90-metre bridge that connects to the production platform, where the wellhead has been leaking.
The structural condition of the platform was found to be unchanged since the complex was evacuated, Total added.
The team of experts will now give Total management a detailed debriefing, enabling them to further develop plans for the well intervention.
The French company, meanwhile, is still planning to carry out a parallel operation of drilling of two relief wells, a longer and more expensive option that could take up to six months.
The leak began after pressure rose in a well that had earlier been capped.
Total has said the leak is costing it $2.5 million a day so far, and it stock has dropped by almost 7 percent since the leak was reported, knocking billions of euros off its outstanding share value.
The crew of eight aboard the helicopter was a mix of staff from Total and Houston-based Wild Well Control.
Firefighters and engineers from the Houston-based company are experts at disasters such as oil rig explosions and have been dubbed Hellfighters by Hollywood.
The UK North Sea's dwindling oil and gas reserves are pushing companies to tap unstable reservoirs at high pressure and extreme heat, while safety checks and maintenance are behind schedule, a North Sea rig auditor who works for the industry told Reuters.
(editing by Jane Baird)