Byford Dolphin
Encyclopedia
Byford Dolphin is a semi-submersible
, column-stabilised drilling rig
operated by Dolphin Drilling, a Fred. Olsen Energy
subsidiary, and currently contracted by BP
for drilling in the United Kingdom section of the North Sea
. She is registered in Singapore
. The rig has suffered some serious accident
s, most notably an explosive decompression
in 1983 that killed five workers and badly injured one.
Byford Dolphin has a length of 108.2 metres (355 ft), breadth of 67.4 metres (221.1 ft) and depth of 36.6 metres (120.1 ft). She has a maximum drilling depth of 6100 metres (20,013.1 ft), and she could operate at a water depth of 460 metres (1,509.2 ft). As a drilling rig, Byford Dolphin is equipped with advanced drilling equipment and has to meet strict levels of certification under Norwegian law. Byford Dolphin is able to maneuver with its own engine
s (to counter drift
and ocean currents), but for long-distance relocation, it must be moved by specialist tugboat
s.
in the Norwegian sector of the North Sea
, four divers were in a decompression chamber system attached by a trunk (a short passage) to a diving bell
on the rig, being assisted by two dive tenders. One diver was about to close the door between the chamber system and the trunk when the chamber explosively decompressed
from a pressure of nine atmospheres
to one atmosphere in a fraction of a second. Five of the men were killed instantly; the other was severely injured.
The situation just before this accident was: Decompression chambers 1 and 2 were connected via a trunk to a diving bell. This connection was sealed by a clamp operated by two tenders, who were themselves experienced divers. A third chamber was connected to this system but was not involved. On this day, divers D1 (35 years old) and D2 (38 years old) were resting in chamber 2 at a pressure of 9 atm. The diving bell with divers D3 (29 years old) and D4 (34 years old) had just been winched up after a dive and joined to the trunk. Leaving their wet gear in the trunk, the divers then climbed through the trunk into chamber 1.
The normal procedure would have been
The first two steps had been completed, and D4 was about to carry out step 3 when, for some reason, one of the tenders opened the clamp, which resulted in explosive decompression of the chamber. A tremendous blast shot from the chamber through the trunk, pushing the bell away and hitting the two tenders. The tender who opened the clamp was killed, and the other was severely injured.
Diver D4 was shot out through the small jammed hatch door opening and was torn to pieces. Subsequent investigation by forensic pathologists
determined D4, being exposed to the highest pressure gradient, violently exploded
due to the rapid and massive expansion of internal gases. All of his thoracic
and abdominal organs
, and even his thoracic spine
were ejected, as were all of his limb
s. Simultaneously, his remains were expelled through the narrow trunk opening left by the jammed chamber door, less than 60 centimetres (23.6 in) in diameter
. Fragments of his body were found scattered about the rig. One part was even found lying on the rig's derrick
, 10 metres (32.8 ft) directly above the chambers. His death was most likely instantaneous and painless.
was large amounts of fat in large arteries
and vein
s and in the cardiac chambers
, as well as intravascular fat in organs, especially the liver
. This fat was unlikely to be embolic
, but must have "dropped out" of the blood in situ
. It is suggested the boiling of the blood denatured the lipoprotein
complexes, rendering the lipid
s insoluble.
The rigor mortis
was unusually strong. The hypostases
(accumulations of blood in internal organs) were light red, and in two cases, there were numerous hemorrhages in the livers. All the organs showed large amounts of gas in the blood vessels, and scattered hemorrhages were found in soft tissues. One of the divers had a large sub-conjunctival
bulla
(a blister in the tissue of the eye).
This incident was also attributed to engineering failure. The obsolete Byford Dolphin diving system, dating from 1975, was not equipped with fail-safe
hatches, outboard pressure gauges and an interlocking mechanism, which would have prevented the trunk from being opened while the system was under pressure. Prior to the accident, Norske Veritas
had issued the following rule for certification: "Connecting mechanisms between bell and chambers are to be so arranged that they cannot be operated when the trunk is pressurized," therefore requiring such systems to have fail-safe seals and interlocking mechanisms.
One month after the accident, Norske Veritas and the Norwegian oil directorate made the law final for all bell systems.
Among others, former crew members of Byford Dolphin and NOPEF (Norwegian oil and petro-chemical union) have come forward and claimed the investigation was a cover-up
. They claimed that the commission investigating the accident did not mention in their report the irresponsible dispensations on vital equipment requested by Comex and authorized by the diving section to the Norwegian Petroleum Directorate, which played a vital role in the accident's occurrence. They also alleged the accident was due to a lack of proper equipment, including clamping mechanisms equipped with interlocking mechanisms (which would be impossible to open while the chamber system was still under pressure), outboard pressure gauges and a safe communication system, all of which had been held back because of dispensations by the Norwegian Petroleum Directorate.
Semi-submersible
A semi-submersible is a specialised marine vessel with good stability and seakeeping characteristics. The semi-submersible vessel design is commonly used in a number of specific offshore roles such as for offshore drilling rigs, safety vessels, oil production platforms and heavy lift cranes.The...
, column-stabilised drilling rig
Offshore drilling
Offshore drilling refers to a mechanical process where a wellbore is drilled through the seabed. It is typically carried out in order to explore for and subsequently produce hydrocarbons which lie in rock formations beneath the seabed...
operated by Dolphin Drilling, a Fred. Olsen Energy
Fred. Olsen Energy
Fred. Olsen Energy is a Norwegian offshore drilling rig company, offering services for the offshore industry within development and production of oil and gas. The company operates in two segments; Offshore Drilling and Engineering & Fabrication, the latter of which includes the Northern Irish...
subsidiary, and currently contracted by BP
BP
BP p.l.c. is a global oil and gas company headquartered in London, United Kingdom. It is the third-largest energy company and fourth-largest company in the world measured by revenues and one of the six oil and gas "supermajors"...
for drilling in the United Kingdom section of the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
. She is registered in Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
. The rig has suffered some serious accident
Accident
An accident or mishap is an unforeseen and unplanned event or circumstance, often with lack of intention or necessity. It implies a generally negative outcome which may have been avoided or prevented had circumstances leading up to the accident been recognized, and acted upon, prior to its...
s, most notably an explosive decompression
Explosive decompression
Uncontrolled decompression refers to an unplanned drop in the pressure of a sealed system, such as an aircraft cabin and typically results from human error, material fatigue, engineering failure or impact causing a pressure vessel to vent into its lower-pressure surroundings or fail to pressurize...
in 1983 that killed five workers and badly injured one.
Description
Byford Dolphin drilling rig is an Aker H-3 design which was built by Aker Group at the Aker Verdal shipyard in 1974. In 1974–1978, she was named Deep Sea Driller.Byford Dolphin has a length of 108.2 metres (355 ft), breadth of 67.4 metres (221.1 ft) and depth of 36.6 metres (120.1 ft). She has a maximum drilling depth of 6100 metres (20,013.1 ft), and she could operate at a water depth of 460 metres (1,509.2 ft). As a drilling rig, Byford Dolphin is equipped with advanced drilling equipment and has to meet strict levels of certification under Norwegian law. Byford Dolphin is able to maneuver with its own engine
Engine
An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines burn a fuel to create heat which is then used to create motion...
s (to counter drift
Drift
- Film and literature :* Drift , a 2002 Doctor Who novel* Drift , a series of Japanese films written and directed by Futoshi Jinno* Drift, 2007 experimental short film by Max Hattler* Drift , a fictional character...
and ocean currents), but for long-distance relocation, it must be moved by specialist tugboat
Tugboat
A tugboat is a boat that maneuvers vessels by pushing or towing them. Tugs move vessels that either should not move themselves, such as ships in a crowded harbor or a narrow canal,or those that cannot move by themselves, such as barges, disabled ships, or oil platforms. Tugboats are powerful for...
s.
| Byford Dolphin specifications | |
|---|---|
| Operating deck load | 3025 tonne |
| Crew quarters | 102 persons |
| Operating water depth | 460 metres (1,509.2 ft) maximum |
| Derrick | 49 metres (160.8 ft) Shaffer top compensator |
| Mooring system | 12 point |
| Blow-out preventer | Hydril 476 mm (18¾ inch), 10,000 kPa (15,000 PSI) |
| Sub Sea Handling System | Christmas tree Christmas tree (oil well) In petroleum and natural gas extraction, a Christmas tree, or "tree", is an assembly of valves, spools, and fittings used for an oil well, gas well, water injection well, water disposal well, gas injection well, condensate well and other types of wells... |
| Deck cranes | 2 x 40 tons |
Diving bell accident
On 5 November 1983 at 4:00 a.m., while drilling in the Frigg gas fieldFrigg gas field
Frigg gas field is a natural gas field in the North Sea, on the boundary between the United Kingdom and Norway. The field is named after the goddess Frigg. King Olav V of Norway officially opened the production on the 8 May 1978. Production was closed at 26 October 2004. The field is situated ...
in the Norwegian sector of the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
, four divers were in a decompression chamber system attached by a trunk (a short passage) to a diving bell
Diving bell
A diving bell is a rigid chamber used to transport divers to depth in the ocean. The most common types are the wet bell and the closed bell....
on the rig, being assisted by two dive tenders. One diver was about to close the door between the chamber system and the trunk when the chamber explosively decompressed
Explosive decompression
Uncontrolled decompression refers to an unplanned drop in the pressure of a sealed system, such as an aircraft cabin and typically results from human error, material fatigue, engineering failure or impact causing a pressure vessel to vent into its lower-pressure surroundings or fail to pressurize...
from a pressure of nine atmospheres
Atmosphere (unit)
The standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of pressure. For practical purposes it has been replaced by the bar which is 105 Pa...
to one atmosphere in a fraction of a second. Five of the men were killed instantly; the other was severely injured.
The situation just before this accident was: Decompression chambers 1 and 2 were connected via a trunk to a diving bell. This connection was sealed by a clamp operated by two tenders, who were themselves experienced divers. A third chamber was connected to this system but was not involved. On this day, divers D1 (35 years old) and D2 (38 years old) were resting in chamber 2 at a pressure of 9 atm. The diving bell with divers D3 (29 years old) and D4 (34 years old) had just been winched up after a dive and joined to the trunk. Leaving their wet gear in the trunk, the divers then climbed through the trunk into chamber 1.
The normal procedure would have been
- close the bell door
- the diving supervisor would then slightly increase the bell pressure to seal this door tightly
- close the door between the trunk and chamber 1
- slowly depressurize the trunk to 1 atmosphere
- open the clamp to separate the bell from the chamber system.
The first two steps had been completed, and D4 was about to carry out step 3 when, for some reason, one of the tenders opened the clamp, which resulted in explosive decompression of the chamber. A tremendous blast shot from the chamber through the trunk, pushing the bell away and hitting the two tenders. The tender who opened the clamp was killed, and the other was severely injured.
Diver D4 was shot out through the small jammed hatch door opening and was torn to pieces. Subsequent investigation by forensic pathologists
Forensic pathology
Forensic pathology is a branch of pathology concerned with determining the cause of death by examination of a corpse. The autopsy is performed by the pathologist at the request of a coroner or medical examiner usually during the investigation of criminal law cases and civil law cases in some...
determined D4, being exposed to the highest pressure gradient, violently exploded
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
due to the rapid and massive expansion of internal gases. All of his thoracic
Chest
The chest is a part of the anatomy of humans and various other animals. It is sometimes referred to as the thorax or the bosom.-Chest anatomy - Humans and other hominids:...
and abdominal organs
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...
, and even his thoracic spine
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
were ejected, as were all of his limb
Limb (anatomy)
A limb is a jointed, or prehensile , appendage of the human or other animal body....
s. Simultaneously, his remains were expelled through the narrow trunk opening left by the jammed chamber door, less than 60 centimetres (23.6 in) in diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
. Fragments of his body were found scattered about the rig. One part was even found lying on the rig's derrick
Derrick
A derrick is a lifting device composed of one tower, or guyed mast such as a pole which is hinged freely at the bottom. It is controlled by lines powered by some means such as man-hauling or motors, so that the pole can move in all four directions. A line runs up it and over its top with a hook on...
, 10 metres (32.8 ft) directly above the chambers. His death was most likely instantaneous and painless.
Medical findings
Medical investigations were carried out on the four divers' remains. The most conspicuous finding of the autopsyAutopsy
An autopsy—also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction—is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present...
was large amounts of fat in large arteries
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
and vein
Vein
In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
s and in the cardiac chambers
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
, as well as intravascular fat in organs, especially the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
. This fat was unlikely to be embolic
Embolism
In medicine, an embolism is the event of lodging of an embolus into a narrow capillary vessel of an arterial bed which causes a blockage in a distant part of the body.Embolization is...
, but must have "dropped out" of the blood in situ
In situ
In situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...
. It is suggested the boiling of the blood denatured the lipoprotein
Lipoprotein
A lipoprotein is a biochemical assembly that contains both proteins and lipids water-bound to the proteins. Many enzymes, transporters, structural proteins, antigens, adhesins, and toxins are lipoproteins...
complexes, rendering the lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s insoluble.
The rigor mortis
Rigor mortis
Rigor mortis is one of the recognizable signs of death that is caused by a chemical change in the muscles after death, causing the limbs of the corpse to become stiff and difficult to move or manipulate...
was unusually strong. The hypostases
Hypostasis
Hypostasis may refer to:* Hypostatic abstraction * Hypostasis , personification of entities* Hypostatic gene* Hypostasis , an Australian-based not-for-profit organization...
(accumulations of blood in internal organs) were light red, and in two cases, there were numerous hemorrhages in the livers. All the organs showed large amounts of gas in the blood vessels, and scattered hemorrhages were found in soft tissues. One of the divers had a large sub-conjunctival
Conjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
bulla
Blister
A blister is a small pocket of fluid within the upper layers of the skin, typically caused by forceful rubbing , burning, freezing, chemical exposure or infection. Most blisters are filled with a clear fluid called serum or plasma...
(a blister in the tissue of the eye).
Investigation
The committee investigating the accident concluded it was due to human error on the part of the dive tender who opened the clamp. It is not clear whether the tender who opened the clamp before the trunk was depressurized did so by order of his supervisor, on his own initiative, or because of miscommunication. At the time, the only communication the tenders on the outside of the chamber system had was through a bullhorn attached to the wall surface; with heavy noise from the rig and sea, it was hard to listen in on what was going on. Fatigue from many hard hours of work also took its toll amongst the divers, who often worked 16-hour shifts. Modifications to the "planned use of overtime" policies were made as a result of further investigation into this incident.This incident was also attributed to engineering failure. The obsolete Byford Dolphin diving system, dating from 1975, was not equipped with fail-safe
Fail-safe
A fail-safe or fail-secure device is one that, in the event of failure, responds in a way that will cause no harm, or at least a minimum of harm, to other devices or danger to personnel....
hatches, outboard pressure gauges and an interlocking mechanism, which would have prevented the trunk from being opened while the system was under pressure. Prior to the accident, Norske Veritas
Det Norske Veritas
Stiftelsen Det Norske Veritas is a classification society organized as a foundation, with the objective of "Safeguarding life, property, and the environment". The organization's history goes back to 1864, when the foundation was established in Norway to inspect and evaluate the technical condition...
had issued the following rule for certification: "Connecting mechanisms between bell and chambers are to be so arranged that they cannot be operated when the trunk is pressurized," therefore requiring such systems to have fail-safe seals and interlocking mechanisms.
One month after the accident, Norske Veritas and the Norwegian oil directorate made the law final for all bell systems.
Among others, former crew members of Byford Dolphin and NOPEF (Norwegian oil and petro-chemical union) have come forward and claimed the investigation was a cover-up
Cover-up
A cover-up is an attempt, whether successful or not, to conceal evidence of wrong-doing, error, incompetence or other embarrassing information...
. They claimed that the commission investigating the accident did not mention in their report the irresponsible dispensations on vital equipment requested by Comex and authorized by the diving section to the Norwegian Petroleum Directorate, which played a vital role in the accident's occurrence. They also alleged the accident was due to a lack of proper equipment, including clamping mechanisms equipped with interlocking mechanisms (which would be impossible to open while the chamber system was still under pressure), outboard pressure gauges and a safe communication system, all of which had been held back because of dispensations by the Norwegian Petroleum Directorate.
Post-investigation
The conclusions of the investigation were disputed, and a group of divers gathered evidence with the intention of "find[ing] justice for all of the crew of Byford Dolphin." The group formed the North Sea Divers Alliance in the early 1990s and now campaigns for compensation for divers killed or injured in the Norwegian Sector of the North Sea.Subsequent lawsuit
The North Sea Divers Alliance, formed by early North Sea divers and the relatives of those killed, continued to press for further investigation and, in February 2008, obtained a report that indicated the real cause was faulty equipment. Clare Lucas, daughter of Roy Lucas, said: "I would go so far as to say that the Norwegian Government murdered my father because they knew that they were diving with an unsafe decompression chamber." The families of the divers eventually received damages from the Norwegian government, 26 years after the tragedy.Other incidents
- In late November 2001, the rig was left adrift without control in a storm. Although 17 of the 71 workers were evacuated by helicopter, the company claimed there was no serious danger.
- On 17 April 2002, a 44-year-old Norwegian worker on the rig was struck on the head and killed in an industrial accidentIndustrial injuryAn occupational injury is bodily damage resulting from working.In the United States in 2007, 5,488 workers died from job injuries, 92% of which were men, and 49,000 died from work-related injuries. NIOSH estimates that 4 million workers in the U.S...
. The accident resulted in Byford Dolphin losing an exploration contract with StatoilStatoilStatoil ASA is a Norwegian petroleum company established in 1972. It merged with Norsk Hydro in 2007 and was known as StatoilHydro until 2009, when the name was changed back to Statoil ASA. The brand Statoil was retained as a chain of fuel stations owned by StatoilHydro...
, who expressed concerns with the rig's operating procedures. The incident cost the company millions of dollars in lost income.