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West Vanguard

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Kristi

Rig: Smedvig West Vanguard Semi-Sub

Date: 06 October 1985

Location: Haltenbanken, Norwegian Continental Shelf

Operator: Statoil

West Vanguard Blowout

According to Norwegian Petroleum Directorate records, Statoil's well 6407/6-2 was 

spudded by the Smedvig West Vanguard on 04 October 1985. The 36" top hole had been 

drilled down to 323m MDBRT with the 30" conductor set at 318m MDBRT. The blow-out 

preventer (BOP) had not yet been installed.

At around 2050 hours on the night of 06 October 1985 while drilling the upper Pliocene 

sediments of the 26" section, a drilling break was observed between 505-508m MDBRT 

with an ROP increase from 40m/hr to 712m/hr. Drilling was stopped at 523m MDBRT and 

the bit was pulled back 15m, after which the well began flowing and unsuccessful attempts 

were made to kill the well by pumping killmud. The bit had entered a shallow gas pocket at 

around 504m causing the well to blow out. A MAYDAY was sent from the rig at about 2310 

and picked up by the Norwegian rescue center at Sola, which directed rescue ships and

helicopters to the crew's aid.

With no BOP used for the top hole section, the flow of gas had been directed through the 

diverter system. This system was unable to contain the flow and the liberated gas exploded 

at around 2320 hours, engulfing the rig in a fireball. The one fatality is assumed to have 

resulted from this explosion, although reports indicate the victim's remains were never

found. The rest of the crew were able to evacuate the rig in a matter of minutes using the

fore lifeboats. The rig's deck structure, two of its legs and the engine room were damaged 

in the blast, resulting in the rig listing by 10 degrees.

By the following day, the fire had burnt out but gas continued to leak out of the well and 

bubble up to the side of the listing, fire-damaged hulk. Reporters flying over the rig noted a 

large hole in one of the rig's legs, extensive fire damage and a fallen crane.

After the accident, the rig was towed to Freifjorden near Kristiansund, Norway and 

investigated by Norwegian police and SINTEF (a Norwegian industrial research institute). 

The investigation revealed that gas initially leaked from the gasket between the riser and 

the slip-joint, forming a gas cloud on the cellar deck level which migrated into the shaker 

house via a poorly closed valve and travelled through an exhaust pipe, across the upper 

deck and into other rooms via air ducts before igniting. To quote the SINTEF report: 'Doors 

and hatches in and around the drilling module on the upper deck were knocked open in a 

pattern that gave indications of the course of explosions.'. The subsequent failure of the 

diverter system was attributed to the extreme flow of gas, drilling mud and sand, which 

eroded holes in pipe bends of the diverter system. Spurts of sand against the metal of the 

rig were suggested as one of the possible ignition sources of the gas cloud.

The rig was restored, returned to work and subsequently sold by Smedvig to Diamond 

Offshore Drilling Ltd. for US$ 68.5 million in December 2002. The rig was then renamed 

Ocean Vanguard, to fall in line with Diamond's rig naming policy.

Historical Footnote

After the blowout, Bergen Underwater Services (BUS) were contracted to locate the 

Vanguard's eight anchors, which had been cut and discarded to allow the Vanguard to be 

moved away from the gas blowout. BUS then deployed an underwater ROV from the M/V 

Arctic Surveyor to find the anchors. During the search, the ROV operator found a crashed 

West Vanguard Blowout - Oil Rig Disasters - Offshore Drilling Accidents Page 1 of 2

http://home.versatel.nl/the_sims/rig/vanguard.htm 11/29/2011
World War II Heinkel He 115 on the seabed, which had been based at Trondheim, Norway 

during the Second World War. The plane had been cut in to two by the movement of one of 

the Vanguard's anchors. The full story of the Heinkel can be read at the NUAV Norway 

During WWII website.

Sources:

Norwegian Petroleum Directorate: West Vanguard well details

SINTEF: West Vanguard report

The Times (UK): 08 October 1985 'Crew flees blazing Norwegian oil rig' 

HSE: Review of issues associated with the stability of semi-submersibles

NUAV crashed Heinkel story

Photos: 

1. Fleumer Aerophoto

2. Canadian Wellsite Gallery

3. Universitetet I Tromso: Chapter 11

4. UWPhoto ANS agency

5. Jan Ove personal website

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http://home.versatel.nl/the_sims/rig/vanguard.htm 11/29/2011