Ocean Ranger
From Wikipedia, the free encyclopedia
The ODECO Ocean Ranger was a semi-submersible mobile offshore drilling unit that sank in Canadian waters on 15th February 1982. It was drilling an exploration well in the Grand Banks area, 267 kilometres (166 miles) east of St. John's, Newfoundland, for Mobil Oil of Canada, Ltd. (MOCAN) with 84 crew members on board when it sank. There were no survivors of the accident.
The Ocean Ranger was designed by engineers of Ocean Drilling and Exploration Company, Inc. (ODECO) and built in 1976 by Mitsubishi Heavy Industries' Yard in Hiroshima, Japan. The rig consisted of a square upper hull supported by eight vertical columns. The columns themselves sat on top of a lower catarmaran-type hull consisting of two parallel pontoons, with each pontoon supporting four columns. The living quarters and drilling package were located on the upper hull. The Ocean Ranger was one of the largest semi-subs working offshore in the early 1980s, approved for 'unrestricted ocean operations' and designed to withstand extremely harsh conditions at sea, including 100 knot winds and 110 foot waves. Prior to moving to the Grand Banks area in November 1980, it had it operated off the coasts of Alaska, New Jersey and Ireland.
On 26th November 1981, the Ocean Ranger commenced drilling well J-34, its third well in the Hibernia Oil Field. The Ocean Ranger was still working on this well in February 1982 when the sinking occurred. Two other semi-submersible rigs were also drilling nearby: the Sedco 706, 8.5 miles NNE, and the Zapata Ugland, 19.2 miles N of the Ocean Ranger. On 14th February 1982, the rigs received reports of an approaching storm linked to a major Atlantic cyclone from NORDCO Ltd, the company responsible for issuing offshore weather forecasts. The usual method of preparing for bad weather involved hanging-off the drillpipe at the sub-sea wellhead and disconnecting the riser from the sub-sea stack. Due to surface difficulties and the speed at which the storm developed, the crew of the Ocean Ranger were forced to shear the drillpipe after hanging-off, after which they disconnected the riser in the early evening of 14th February 1982.
At about 1900 hours local time, the nearby Sedco 706 experienced a large, powerful wave which damaged some items on deck and caused the loss of a life raft. Soon after, radio transmissions were heard from the Ocean Ranger, describing a broken portlight (a porthole window) and water in the ballast control room, with discussions on how best to repair the damage. Some time after 2100 hours, radio conversations originating on the Ocean Ranger were heard on the Sedco 706 and Zapata Ugland, noting that valves on the Ocean Ranger's ballast control panel appeared to be opening and closing of their own accord. The radio conversations also discussed the 100 knot winds and waves up to 65 feet high. Through the remainder of the evening, routine radio traffic passed between the Ocean Ranger, its neighbouring rigs and their individual support boats. Nothing untoward was noted.
At 0052 hours local time, on 15th February, a MAYDAY call was sent out from the Ocean Ranger, noting a severe list to the port side of the rig and requesting immediate assistance. This was the first communication from the Ocean Ranger identifying a major problem. The standby vessel, the M/V Seaforth Highlander, was requested to come in close as countermeasures against the 10-15 degree list were proving ineffective. The onshore MOCAN supervisor was notified of the situation, and the Canadian Coast Guard and Mobil-operated helicopters were alerted just after 0100 hours local time. The M/V Boltentor and the M/V Nordertor, the standby boats of the Sedco 706 and the Zapata Ugland respectively, were also despatched to the Ocean Ranger to provide assistence. At 0130 hours local time, the Ocean Ranger transmitted its last message: 'There will be no further radio communications from the Ocean Ranger. We are going to lifeboat stations'. In the middle of the night, in the midst of atrocious winter weather, the crew abandoned the rig at around 0130 hours. The rig remained afloat for another 90 minutes, sinking between 0307 and 0313 hours local time.
Whilst the rig was provided with an Emergency Procedures Manual which detailed evacutation procedures, it is unclear how effectively the rig evacuation was carried out. There is evidence that at least one lifeboat was successfully launched with up to 36 crew inside, and witnesses on the M/V Seaforth Highlander reported seeing at least 20 crew members in the water at the same time. The United States Coast Guard speculated that 'these men either chose to enter the water directly or were thrown into the water as a result of unsuccessful lifesaving equipment launching'. Rescue attempts by the standby vessels were hampered by the adverse weather conditions and the conclusion that the standby boats were neither equipped nor configured to rescue casualties from a cold sea. As a result of the severe weather, the first helicopter did not arrive on scene until 0430 hours local time, by which time most if not all of the Ocean Ranger's crew had succombed to hypothermia and drowned. Over the next week, 22 bodies were recovered from the North Atlantic. Autopsies indicated that those men had died as a result of hypothermia.
A Canadian Royal Commission spent two years looking into the disaster. The commission concluded that the Ocean Ranger had design and construction flaws, particularly in the ballast control room, and that the crew lacked proper safety training, survival suits and equipment. The United States Coast Guard concluded that the rig's list was a result of either a ballast control malfunction or human error, or a combination of the two, causing, at some point, valves to operate which allowed water to enter the rig's forward ballast tanks. The rig listed to such a degree that boarding seas flooded the forward chain lockers, causing the immersion and flooding of the upper hull. This resulted in a loss of buoyancy great enough to cause the rig to capsize by the bow and then sink.
The Canadian Royal Commission also concluded that inspection and regulation by United States and Canadian government agencies was ineffective. In addition to key recommendations for Canada's offshore oil and gas industry, the commission recommended that the federal government invest annually in research and development for search and rescue technologies, such as improving the design of lifesaving equipment—a commitment that has been met in every fiscal year since 1982.
