May 23, 2011 8:52 A.M. ET
By JAMES HERRON
LONDONRoyal Dutch Shell PLC has been rapped by Norway’s Petroleum Safety Authority for a maintenance error on an oil well that had “major accident potential” and risked an oil leak.
The incident occurred Dec. 4, 2010 on Norway’s Draugen field, which produces around 50,000 barrels of oil a day, the PSA said on its website Monday. An operation to replace a subsurface gas valve went wrong, the device became stuck inside and blocked the operation of another piece of machinery called a Christmas Tree, which sits atop the wellhead, it said.
“The incident didn’t result in any injury to personnel,” the PSA said. “However, the incident involved major accident potential in a situation with only one remaining barrier against hydrocarbon outflow from the well.”
Shell wasn’t immediately able to comment on the PSA’s conclusions.
The failure of all barriers to hydrocarbon flow from a well is very serious. An out-of-control well caused the explosion that destroyed the Deepwater Horizon drilling rig last year, resulting in a three-month oil spill from a BP PLC well in the Gulf of Mexico.
Shell’s management, risk assessment, well control, well barriers and reporting of drilling activities during the Draugen incident were inadequate, the PSA said. It ordered Shell to improve its procedures for well intervention, well control and internal investigations by June 1.
The incident on Draugen wasn’t the only potentially dangerous well-control problem in Norway last year. In May 2010, Norwegian oil firm Statoil ASA‘s Gullfaks C platform was evacuated after it experienced recurring pressure problems in a well.
The PSA described the incident as “very serious” and concluded that “only luck averted a subsurface blowout [and] explosion, and prevented the incident from developing into a major accident.”
The number of well-control incidents per well drilled offshore in Norway has increased notably in recent years, according to the PSA’s annual report. In 2010, 28 well control incidents were reported, up from just 11 in 2008, it said.