Norway’s Petroleum Safety Authority (PSA) has begun an investigation of a well control incident on the Visund field on 17 March 2016 that caused Statoil to put a halt to production and evacuate workers in the North Sea.
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Visund. Image from Statoil. |
The PSA's investigation will focus on Statoil's planning and execution of the well operation.
An inflow and pressure increase were registered in the well's annulus. Production on the field was halted and the operator began demanning the facility. The BOP was intact, but problems were reported in operating shutoff valves on the top of the drillstring. The situation was normalized on 18 March, the PSA said.
The incident did not cause any hydrocarbon leaks.
The PSA's investigation will include clarifying the chain of events and identifying proximate and underlying causes.
Last week, Statoil put a halt to production and evacuated workers at its Visund platform in the North Sea, after a build up of well pressure occurred on Wednesday (16 March).
“It’s a controlled well situation and production is halted while in progress,” Morten Eek, Statoil spokesman told the Stavanger Aftenblad. “It is difficult to say how much time it will take, but we hope to get back normal pressure as quickly as possible.”
Statoil said that on Wednesday afternoon, the company discovered a pressure build-up during preparation of the well. As of Thursday, (17 March), tests confirmed that pressure is still occurring at the well.
Statoil has closed off the well, however, it may take some time before production can start up again, Eek said.
Statoil evacuated 48 non-essential workers from the platform on Wednesday, and left 67 people have been left onboard to assist with work on the well.
Visund is an oil and gas field located in Blocks 34/8 and 34/7, some 22km northeast of the Gullfaks field in the Tampen area of the Norwegian North Sea.
The development comprises a semisubmersible steel production, drilling and quarters platform (Visund A). Water depth in the area is around 335m. The northern part of Visund has been developed using a subsea template, around 10km north of Visund A.
The subsea-completed wells on the field are tied back to the floater with flexible risers. Oil is piped to Gullfaks for storage and export. The Visund field began producing gas and exporting it to continental Europe on 7 October 2005. Visund came onstream in spring 1999.
Statoil is the operator of Visund with 53.2% stake. Partners include Petoro (30%), ConocoPhillips (9.1%), and Total (7.7%).
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