STAVANGER, Norway -- Statoil has re-started production through the Gullfaks C platform in the Norwegian North Sea, after a shut-down on May 19 caused by problems with well C-06.
A change in pressure and loss of drill fluid resulted in the loss of one barrier in the well, with further uncertainty over the integrity of the remaining barrier. Statoil has since focused on plugging the well systematically from the bottom and up.
“We’ve now installed three cement plugs and one mechanical plug in the well,” said Rune Gaasø, acting head of Gullfaks drilling and well operations. “This isolates the well from the reservoir and a high-pressure zone in the Shetland/Lista formation. The barriers are now intact, and we have given the green light for normalization.”
Analysis revealed a hole in a casing at a depth of 1,400 m (4,593 ft). The well at present is stable, with no leaks reported.
“We’re now going to work to seal the hole before we temporarily abandon the well and facilitate re-use of the well slot,” Gaasø explained.
During operations to put barriers back in place in the well, Statoil says it applied techniques designed to minimize the risk of escalating the situation. The Gullfaks organization has prepared a detailed start-up plan which is more extensive than after a normal maintenance turnaround, the company points out.
Statoil has appointed an investigation team to examine the incident, and hopes to draw relevant lessons for future well construction.
Also in the North Sea, Petroleum Safety Authority Norway has authorized Statoil to use the West Venture semisubmersible for drilling and well activities on the Troll field. West Venture, operated by Seadrill, has been in operation at Troll Olje since March 2000.
The consent, which runs through July 31, 2015, covers production drilling, delineation and observation wells, completion, well overhaul, and intervention including coil tubing, P&A, and workover of wells on Troll Olje.
Additionally, Statoil won clearance from PSA to use the new Troll O2 subsea template with pipelines, which will be connected to the Troll C platform.
Troll 02 is 6 km (3.7 mi) north of Troll C, and will be the 16th subsea template connected to this facility. The tie-in will be performed by connecting the pipeline and umbilical to the existing subsea template on Troll O1 and using the existing production pipeline from Troll O1 to send the oil to Troll C.
Water depth at the site ranges from 330-350 m (1,082-1,148 ft). Start-up is scheduled for July 20.
Statoil secures Gullfaks C well
Statoil has re-started production through the Gullfaks C platform in the Norwegian North Sea, after a shut-down on May 19 caused by problems with well C-06.