Remembering The Ocean Ranger

Remembering The Ocean Ranger

Accident Investigation and Lessons Learned

Name: [CHRIS AMPIAH]E-mail: [cyampiah@yahoo.com]London South Bank UniversityDepartment of Applied ScienceFaculty of Engineering, Science and the Built Environment103 Borough Road, London, SE1 0AAwww.lsbu.ac.uk

ABSTRACT

The Ocean Ranger was the worlds largest mobile offshore drilling unit (MODU) when it developed a severe list and sank off the coast of Newfoundland in February 15, 1982 taking with it the lives of all 84 crew members aboard. This loss of life and property was as a result of a combination of several preventable incidents ultimately leading to a crescendo of fatalities. A timeline of how the events unfolded has been constructed to set the pace for further understanding of the mechanism behind this accident. It was established that, the series of chain events was initiated by a vicious storm passing over the Newfoundland area at that time. So severe was the storm that, this engineering marvel lost its structural integrity, and coupled with a number of factors such as human error and other engineering errors, the rig succumbed to the pressures of the storm and sank. An event tree and fault tree constructed for the purposes of this study provided further insight into the various paths available for the turn of events and the probability of such events occurring. A further root cause analysis confirmed that the loss of the Ocean Ranger was the result of not any one factor alone but a dint of bad luck, several design flaws exacerbated by lack of training and human errors. Following this epic accident that plagued the oil and gas industry, a new paradigm of health and safety improvement regulations were instituted particularly in the global offshore industry. In conclusion, the Ocean Ranger disaster could have been prevented had there been a rigorous emergency plan instituted in conjunction with proper training and drills for all personnel on board, as well as the provision of life saving equipments.INTRODUCTIONThe Ocean Ranger was an engineering milestone achieved in the 1970s and deemed the largest semi submersible Mobile Offshore Drilling Unit (MODU) in the world at time of its completion in 1976. Owned by Ocean Drilling and Exploration Company (ODECO), it was built by the Japanese firm Mitsubishi in Hiroshima, Japan and was designed to operate in the harshest of environmental conditions, or so it was claimed. As the pride of the offshore industries breaking new frontiers, the Ocean Ranger was thought to be unsinkable at that time. However, this self-propelled semi-submersible rig sank whiles drilling in the Hibernia oilfield in the Grand Banks area 267 kilometres off St Johns, Newfoundland, Canada. On Valentines Day the 14th of February, 1982, the submersible drilling rig, was battered by a ferocious storm which broke a port light causing the ingress of water and the subsequent short circuiting of control equipment panels. After about a 16 hour struggle to regain control of the rig, it finally toppled forcing all 84 crew aboard to instinctively jump into the icy cold waters for a chance of survival. Unfortunately, all of these bold crew men were never to be seen alive again despite a concerted effort by nearby vessels to rescue them. This seemingly unsinkable marvel of technology had been overpowered by the forces of nature in the freezing North Atlantic Ocean, History:In the 1960s Canada embarked on a quest to prospect oil reserves off its eastern sea boarders and this drive was well underway by the 1970s . In 1979, increased exploration activities focusing on the Grand Banks discovered the Hibernia Oilfield off the coast of Newfoundland. The Ocean Ranger drilling rig was thus, contracted by Mobil Canada (MOCAN) to drill delineation wells to map out the Hibernia Oilfield beginning in 1980 [3].

Fig.1 - Geographical location of the Hibernia oil field relative to St Johns, Newfoundland [2]Drilling Locations HistoryBecause the Ocean Ranger was a drilling rig rather than a production rig, it was normally deployed at drilling sites or in some cases at a standby location. Table 1 lists the period and geographic location where the Ocean Ranger was engaged in offshore drilling operations [3].Tab. 1 - Ocean ranger drilling location and days spentYearGeographical LocationNumber of days

1980 - 1982Grand Banks off Newfoundland465

1980Off coast of Ireland126

1979/1980Baltimore Canyon166

1977Lower Cook Inlet111

1976/1977Gulf of Alaska232

1976Bering Sea99

Severe Weather History:The US Coastguard Report (1983) laments that weather and sea data recorded by the Ocean Ranger indicated the rig had experienced over 50 significant storms whilst drilling at the various locations indicated in Table 1. From the records, it was also retrieved that the rig had experienced the most severe weather from 16th to 20th January, 1982 while drilling in the Hibernia Oilfield. The report further states that this storm had negligible effect on the Ocean Ranger apart from altering its position over the well due to lose anchor tensions. During the course of this 5 day severe weather period, the marine riser was disconnected on two occasions due to heaving of the drilling rig caused by the terrible weather, resuming drilling only when the weather and sea subsided [3].Incident History:On 6th February, 1982, the Ocean ranger underwent a rather uncharacteristic list (tilt) to 6 degrees whiles receiving fuel and drilling fluid supplies. A general evacuation announcement was made over the public address system for all hands to don life jackets and report to the lifeboat stations. The evacuation was eventually halted as the list was subsequently corrected to normal.UNIT DESCRIPTION:The Rig:The Ocean Ranger was a semi submersible drilling rig capable of self propulsion designed for deepwater operations in water depths up to 3000 feet [1]. Its design and construction ensured it could withstand extremely harsh environmental conditions including simultaneously occurring 100 knots winds, 3 knots surface current and 110 feet tall waves. The length and width of the rig was 122 meters (400ft) and 80 meters (262 ft) respectively. It stood at a height of 46 meters (151ft) excluding the derrick. The blueprints of the rig consisted of a platform or upper haul, mounted on top of eight vertical columns which were in turn attached to a lower catamaran-type hull consisting of two oval pontoons parallel to each other (Fig. 2 and 3). The upper haul served as a living and working quarters for the crew whilst the two pontoons were used to achieve the right level of structural flotation. Rig stability was achieved by the eight columns capable of elevating the platform above the normal effects of the sea. The entire rig weighed in at 14,913 tons gross whereas its net tonnage was 12,097 .The platform was made up of the upper deck and the lower deck. The upper deck consisted of the drilling floor and derrick, the cranes, the anchor windlasses, the helicopter deck, storage racks for drilling pipes, casings and risers, the crews upper living quarters, office space and work areas, and the lifeboat. The lower deck housed the generator room, the cellar areas, the mud system, storage areas and the lower two floors of the crews quarters.Fig. 2 - Side elevation of the Ocean Ranger structure [3]

Fig. 3 - Front Elevation of the Ocean Ranger structure [3]

PontoonsThe two pontoons of the lower hull were ovular in cross-section with dimensions 122 meters long, 19 meters wide with a depth of 7 meters (400ft*62ft*24ft) each. These pontoons carried on their topside, eight platform-supporting columns, arranged in a rectangular fashion and were each referred to as the starboard pontoon and the port pontoon respectively, each supporting four vertical columns. Apart from providing flotation to the rig structure, the pontoons also contained ballast water, fresh water, drill water and fuel oil tanks. In each pontoon were 16 tanks and aft of these tanks was situated a pump room inside each pontoon. Aft of each pump room was a propulsion room which contained two 3500 Horse Power DC electric motors per pontoon. These electric motors together provided 14000 total shaft Horse power drive to two steerable ducted propellers for propulsion.

The Ballast Control Room located in one of the eight columns, controlled the rigs ballast system. From this room, personnel could remotely open and close valves and operate ballast pumps. By manipulating the ballast water, the control room operator could increase or decrease the draft (sinkage) of the rig, induce or remove trims and heels. Thus, the distance between the rigs waterline and the lowest point on the pontoon was controlled by varying the amount of ballast water in both port and starboard pontoons

Mooring systemA 12 point mooring system consisting of twelve 45,000 pound anchors was used to maintain the Ocean Ranger in position at a drilling site as illustrated in Fig. 4. Theses anchors were normally housed on the rig by tensioning them up against the anchor bolster located at the base of the four corner columns. Anchor handling boats would run the anchors out from the rig and position them on location during deployment to a particular well site.;Fig. 4 - Top elevation of the Ocean Ranger Mooring system [3]The ballast control room:This room was located in column SC-3, the third column aft, starboard side of the pontoon. The room deck was about 28 ft above the drilling draft water line. The general plan of the ballast control room is depicted in Fig. 5. There were four port lights (glass windows) built in the column, which allowed the operator in the room to visually observe sea conditions and the vessel draft. Each port light was permanently installed according to Japanese Standards Association and could not be opened. However, interior metal closures called deadlights were provided, which when shut, covered the port lights from within. The ballast control console was also located across the forward section of the ballast control room, such that the operator always faced forward when operating the console.

Fig. 5 - Top view of the Ballast control room layout [3]Supply ShipsThe Canadian government required each oil rig to have a dedicated standby vessel stationed nearby in case of an emergency. These vessels also supplied food, water, and fuel to their respective units. The Seaforth Highlander served as the Ocean Rangers standby vessel and stood off approximately five miles away from the Ocean Ranger in compliance with safety regulations.

AVAILABLE EMERGENCY EQUIPMENT

The primary lifesaving equipment on board the rig consisted of two 50-man totally enclosed lifeboats, made of fibre glass reinforced plastics located on the upper deck. The lifeboats were designed to be self-righting provided all personnel were strapped in their seats with no significant accumulation of water inside. Additionally, there were 10 Coast Guard approved 20-man inflatable life rafts onboard with a total capacity of 200 persons all located on the upper deck; four on the stern, two on the starboard side, two on the port side, and two on the bow. In addition, the Seaforth Highlander was also at the beck and call of the Ocean Ranger. 16

Event 11: Damaged lifeboats found capsized by rescue vessels.Event 9: Standby vessel arrives. Attempts rescue.Event 10: Ocean Ranger sinks. Rescue attempts fail. Event 2: Drilling halted with complications.Event 4: Loss of control. Rig begins to tilts due to uncontrolled valve opening and closure.Event 6: Rig tilts severely to the portside .All counter measure are ineffective. First mayday call sent. Event 7: Standby vessel and aerial evacuation requested.Event 8: Last radio transmission. Crew headed for lifeboats.14.0016.4219.4521.3022.5000.5201.0001.3001.5003.100700 Event 5: Routine checks with nearby vessels.Event 3: Large wave hits rig and breaks port light. Sea water floods ballast control room. Event 1: Vicious storm in Hibernia Field.Fig. 6 The Ocean Ranger disaster timelineMECHANISMS AND HYPOTHESES

Event recollection is solely being based on radio transmissions between the Ocean Ranger, two other semi-submersibles drilling nearby, (Sedco 706 and Zapata Ugland), Seaforth Highlander, and the MOCAN superintendent stationed in St. Johns due to the loss of all 84 crew .Post accident investigation of the rig by ROV and divers was used to recover key components of interest, as well as to perform a comprehensive structural inspection [3].Ballast control room port light failureThe initial event that led to the loss of the Ocean Ranger was the failure of the port lights in the ballast control room. The exact cause of failure is unknown but has been attributed to an impacting wave. It is of my opinion that the port light had initially suffered some structural integrity issues, ultimately failing to withstand the impact of the wave on that fateful night. Some argue that the deadlight (metal safety shutters) could have been secured earlier at the onset of the storm to prevent port light failure but realistically, the port lights were needed open at all times so that the ballast room controller could observe directly, the rigs position above the sea. Plus the rig crew had also been made to believe that the rig was unsinkable and that nothing could go wrong. Ballast control equipment failureFollowing the port light shattering in the ballast control room, a substantial amount of sea water immediately entered the room via avenues created by the broken port light. Even though the crew then shut the deadlight window immediately after sea water ingress, it was too late as the sea water was sufficient enough to trigger a major electrical malfunction of the ballast control console.Forward list developsAs a direct result of this ballast room malfunction, several valves in the rigs ballast system located in the pontoons begun to open and close uncontrollably. This either allowed more sea water to enter into the rigs forward ballast tanks or caused the onboard ballast water to drain towards the forward ballast tanks causing the rig to develop an initially forward list. The degree of list and the magnitude of draft increase were sufficient to allow for the ingress of flood water into the rigs forward chain lockers through the pipe and wire trunk opening on the top corner columns.Crew begins evacuationThe exact reasons for this decision to abandon the rig is unknown since the rig remained afloat for approximately 1.5 hours before sinking. That the crew may have acted out of panic, desperation and the lack of in-depth knowledge regarding emergency procedures. Hence their only instinctive act was to ice of action. It is suspected that all crew members abandoned the rig by either jumping into the freezing turbulent sea or via lifeboats with only so much on as their regular clothes and life jackets. List worsens until total submersionThe immediate cause of the loss of the Ocean Ranger was the progressive downloading of the chain lockers in the forward columns and the subsequent flooding of the rigs upper hull, resulting in the capsize of the rig by the bow. The capsizing motion caused the rigs pontoons to make contact with the sea floor as it turned over, damaging the forward ends of both pontoons. Rescue effort Amidst the torrential storm, The Seaforth Highland vessel was able to manoeuvre its way close to one life boat with several survivors on board. Efforts to safely transfer the crew however, ended in a catastrophic capsize of the lifeboat as its stability was compromised by the efforts of the crew to transfer safely to the Seaforth Highlander. The lifeboat was designed to have inherent self-righting stability only when the occupants were strapped into their seats. Thus as the men frantically started to transfer, the boat lost stability plunging the crew into the icy cold sea. Rescue crews noted that victims in the water were unable to help themselves when life rings and other devices were thrown at them Out of the 84 crew on board the rig, only 22 bodies were recovered by search teams and all were found to have died from hypothermia according to autopsy reports. Search teams were also able to recover 2 lifeboats and 6 life rafts, all in disarray, over the course of the next four days. In hindsight, the missing 62 crew most likely also died as a result of severe hypothermia. Fig. 7 - Event Tree Analysis0.510.90.70.5230.10.5450.30.90.80.560.50.175x10-60.280.59Port light failureWater Ingress to control roomForward list developsIneffective counter measuresCrew evacuation under stormy weather conditionsBallast control equipment disabledForward Chain lockers floodRig listing continues until capsizeSuccessFailure0.10.9

Event tree guide Tab. 2 - Event tree GuidePathwayConsequence

1Port light fails, water enters ballast control room, equipments short-circuits in the ballast control room, forward list develops, all counter measures fail, forward chain lockers flood, rig list severely and the crew successfully abandon the sinking rig. Crew ok. Rig is lost

2Port light fails, water enters ballast control room, equipments disable in the ballast control room, forward list develops, all counter measure fail, forward chain lockers flood, rig list severely and the crew fails to successfully abandon ship due to sever storm. Rig and crew are lost.

3Rig does not continue to list severely, giving the crew time to evacuate successfully. Crew ok .Rig is somewhat ok.

4Rig does not continue to list severely, but the crew are unable to evacuate due to sever storm battering them. Crew lost. Rig is ok.

5Forward chain lockers do not flood due to a safety cover that seals them. Rig is ok. No need for evacuation

6Counter measures to save the rig proves effective to competence operators. The rig is saved from further listing and the crew remain on board without evacuating. Crew and rig are ok.

7Ballast control room equipment is water resistant and does not short circuit. Rig control is not lost. Rig is ok. Crew is ok.

8Sea water fails to enter the Ballast control room. Room is dry and all equipments function fine. Rig is ok. Crew is ok.

9Deadlight secures the opening and port light does not shatter Rig stays afloat. Rig is ok. Crew is ok.

ROOT CAUSE ANALYSIS The loss of the MODU OCEAN RANGER was not the result of any one action, but rather a disastrous chain of events as discussed already. It was the culmination of several minor design flaws and several human factors. It is quite probable however, that this could have been prevented or damages minimised. The contributing causes of capsize and the subsequent sinking of the Ocean Ranger are listed below. Human factors/errors: Lack of understanding of ballast control system Lack of understanding of rig stability concepts Failure to properly address the listing incident of February 6, 1982 Operational issues: production pressures forcing the crew to continue drilling into the storm Lack of detailed ballast control procedures in the operating manual Lack of personnel training and certificationEngineering/design issues: Poor ballast control design Poor position of the ballast control room Lack of watertight chain lockers Absence of control instrumentation especially in the chain lockers Inability to pump water out of chain lockers Evacuation and Rescue issues: Lack of insulated and waterproof suits to complement life jacket Lifeboat design flaws Lack of proper equipments to transfer victims from lifeboat to standby vessel Lack of equipment to recover unconscious victims from the stormy sea such as drag nets and hook

Fig.8 Fault TreeLoss of lifeFutile rescue effort from stand by vesselsSevere stormy weatherCapsizing rigIncorrect evacuation procedureLack of appropriate equipmentPoor weather conditionsDesign flawsIncompetent crewWater ingress to ballast control roomIneffective counter measuresBroken Port light windowInitial Flooding and listing of rigBallast control console rendered inoperable Flooding and listing of rig worsensAND gateOR gateKEYWave impactStructural failureTOP EVENTCONCLUSION The capsize of the Mobile Offshore Drilling Unit (MODU), the Ocean Ranger, was a horrific disaster resulting in the loss of 84 lives. Initiated by a broken portlight, the chain of events that followed could have been prevented through proper personnel training, zero tolerance for production pressure at the expense of health and safety, proper emergency planning, and integrity in our daily engineering workings.REFERENCES

1. Government of Canada. (1984) Royal Commission on the Ocean Ranger Marine Disaster Volume 1 & 2. Ottawa, Ontario.2. The Canadian Encyclopaedia, Ocean Ranger. [Online] Available at: http://www.thecanadianencyclopedia.com/articles/ocean-ranger.[Accessed:15, May, 2014]3. U.S. Coast Guard Marine Board of Investigation.(1983) MODU Ocean Ranger, Capsizing and Sinking in the Atlantic Ocean on February 15, 1982 with Multiple Loss of Life. United States Coast Guard. Washington D.C.

Cover image by:Vingh,C. (2014) Sunken Ocean Ranger. [Online] Available at: http://charlesvinh.daportfolio.com/gallery/227981. [Accessed: 22 August, 2014]