Risk Assessment in Offshore: Lessons from Piper Alpha & Macondo

This report provides a comprehensive analysis of risk assessment and accident prevention in offshore oil extraction, highlighting the critical role of safety barriers and human factors. It includes a comparative study of two major offshore oil rig accidents: the Piper Alpha disaster of 1988 and the Macondo Deepwater Horizon blowout of 2010. The report examines the causes and consequences of these accidents, focusing on the failures in communication, safety protocols, and decision-making that contributed to the catastrophic outcomes. It also assesses the performance of safety barriers, such as the Bottomhole Kickoff Assembly (BHKA), and identifies key lessons learned to improve safety and prevent future accidents in the offshore oil industry. The study concludes that a combination of human error and malfunctioning safety measures led to these disasters, emphasizing the need for improved risk management and safety culture in offshore operations. Desklib provides access to this and other solved assignments.

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Table of Contents
Introduction......................................................................................................................................2
Role of risk assessment in the offshore major accident prevention.................................................2
Piper Alpha (1988)..........................................................................................................................3
Macondo Blowout (2010)................................................................................................................4
Performance of the safety barriers...................................................................................................4
Conclusion.......................................................................................................................................5
Reference.........................................................................................................................................6
Appendix..........................................................................................................................................8

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Introduction
Offshore oil extraction is one of the most dangerous job in the world. Workers that reside
in the offshore oil rig drilling farms are constantly exposed to the hazardous environment of
highly inflammable materials, heavy machinery and harsh weather. These hazardous working
conditions often lead in to offshore accidents which result in to fatalities and serious injuries. The
most common accidents that occur in an offshore oil rig platform are the explosion and fires.
Welding, electrical work, and flammable materials are the common causes of fire in an offshore
oil rig. Oil rig fires are difficult to contain and it might take hours or even days to fully
extinguish the fire (Ismail et al. 2014). This study is based on the roles played by risk assessment
and accident investigation in the offshore accident prevention. It also includes a comparative
analysis of two major offshore oil rig accident.
Role of risk assessment in the offshore major accident prevention
Risk assessment provides an insight of the probable risks that may arise in future if
precautionary step are not followed. The role of risk assessment is to find out the several factors
that contribute to offshore oil rigs accidents, which are as follows:
 Flaws in the safety culture- safety norms governs the actions of an organization or a
whole industry that has inherent risk associated with it. Safety culture can be attributed to
the overall culture of an organization where safety culture is considered as a subset. This
subsets reflects the general attitude of an organization towards the risk management and
maintenance of safety. Operation that involve risk have an inherent chance of risk
occurrence and thus risk assessments are conducted. The management however remains

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unwilling to listen to any negative analysis and accidents occur when operational flaws
are not addressed (Vinnem 2013).
 Improper implementation from the prior occurrences- accidents occur and even after a
proper analysis of the incident, the necessary changes and modifications are not done to
prevent its recurrence. Risk assessment here plays a major role in identification of such
loop holes that contribute to oil rig accidents in future (Vinnem 2013).
Accident investigation in offshore major accident prevention- The importance of accident
investigation deeply lies in reducing the chances of recurring of the same incident again.
Especially in offshore oil rigs a small mistake and negligence can lead to a disaster. Thus, the
role of an accident investigation is to identify the human or the technical error that have led to an
offshore oil accident (Xue et al. 2013).
Piper Alpha (1988)
Piper Alpha is an oil rig platform which was located in North Sea (Piper filed) of United
Kingdom. This oil field is located northeast of Aberdeen which is approximately 120 miles. The
platform was in 474 feet in water and was operated by a Californian based company called
Occidental Petroleum (Cullen 1993). The platform was the United Kingdom’s largest and was
made up of 4 different modules. The platform used to pump natural gas and crude oil from the 24
different wells which was delivered to the Flotta oil terminal located in Orkney via three
pipelines. Piper Alpha used to produce 250,000 barrels per day and later it increased to 300,000
barrels per day. However, it later declined to 125,000 barrels per day (Paik et al. 2011).
On 6th July, 1988 work started on one condensate-injection pump (A) which were named
as A and B. This was done to compress the gas and transport it to Flotta. From the compressor A,

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a pressure safety valve was opened for the purpose of recertification and recalibration. The
dayshift crew ended work for that day. In the evening time, the second shift started the pump B
and also decided to bring the pump A back to service (Cullen 1993). This led to gas leakage and
the platform exploded and resulted in the death of 167 men which included a fast rescue craft
and 2 operators. 62 men survived because they jumped into the sea from the burning platform
(Broadribb 2015).
Macondo Blowout (2010)
In the year 2008, a company named BP leased a portion of the sea floor located in Gulf of
Mexico and is 50 miles from the shores of Louisiana. The plot of the sea floor was named as
Macondo. For the purpose of drilling company called Transocean was called. The drilling rig
was 122 meter and 400 feet tall, while the drilling was bigger than a football field. On April 20th,
2010 under high pressure methane gas moved up through the drill column. The gas then
expanded on the rig and got ignited and eventually exploded. Majority of the workers escaped
the catastrophe, while 11 workers were reported to have died from the explosion. The Deepwater
Horizon burnt for 36 hours and then it sank. This resulted in to an unpresented oil spill in to the
Gulf of Mexico, a huge environmental disaster (Safina 2011).
Performance of the safety barriers
Safety barriers are the non-physical and the physical ways of planned or integrated in a
system to control and prevent accidents and any undesired events. Safety barriers range from
multiple technical system or human actions or the amalgamation of both are utilized for the
prevention of any accident in offshore oil rigs. Here, the word prevention relies heavily on
reduction of the occurrence of any risk (Landucci et al. 2015).

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Bottomhole Kickoff Assembly (BHKA) is an effective tool which is used to set cement
plugs in to on horizontal holes and places which is highly deviated. This tools helps in setting
competent and balanced cement plugs and reduces the hassle of adding additional plugs during
oil drilling operations (Halliburton 2018).
Piper Alpha- the safety barriers that did not function at Piper Alpha are: Communication,
passive fire protection, fire protection system, evacuation facilities, delayed decision making,
platform layout, permit to work system (Saleh and Pendley 2012).
Macondo Blowout- When the blowout occurred, bottomhole cement was the only active
barrier. When the mud got removed, an underbalance was created and the blowout preventer
(BOP) was open. The BP Company decided not to put any additional barrier in place of the
displaced barrier (mud) in the riser. The bottomhole cement turned in to foam which later
became unstable and resulted in the accident. Human error occurred when the negative pressure
was misinterpreted, and the operators failed to identify the influx during the displacement of the
mud (Skogdalen, Utne and Vinnem 2011).
Compare and contrast
In both the accidents, the major causal factor that caused the accident is the human error.
In both Piper alpha and Macondo blowout, the failure to convey the necessary and vital
information to the respective responsible people.
The major contrasting causal factor is the lack of communication during the shift change
in Piper alpha. The dayshift workers ended the day without properly communicating that the
pump A was under service, this led to the leakage of gas (Broadribb 2015). While in the
Macondo case, a drill test was carried out in which the pressure buildup in to the pipes were not

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analyzed correctly and this led to an accident. This accident was later called as Macondo blowout
(Safina 2011).
Conclusion
Thus, from the above discussion it can be concluded that, oil rig accidents were the result
of mixed failure from both the humans and the safety barriers placed to counter any accident.
The malfunction in both the cases occurred due to the errors in human judge and
miscommunication. Thus, making both these crucial when operating in an oil rig platform.
Accidents in oil rig platforms results in both loss of biodiversity and loss of billions of dollar of
money.

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Reference
BBC News, 2018. Piper Alpha: In their own words. [online] BBC News. Available at:
http://www.bbc.com/news/uk-scotland-22840445 [Accessed 12 Feb. 2018].
Broadribb, M.P., 2015. What have we really learned? Twenty five years after Piper Alpha.
Process Safety Progress, 34(1), pp.16-23.
Bryant, B., 2018. Deepwater Horizon and the Gulf oil spill - the key questions answered. [online]
the Guardian. Available at: https://www.theguardian.com/environment/2011/apr/20/deepwater-
horizon-key-questions-answered [Accessed 12 Feb. 2018].
Cullen, L.W.D., 1993. The public inquiry into the Piper Alpha disaster. Drilling Contractor;
(United States), 49(4).
Halliburton, 2018. [online] Halliburton.com. Available at:
http://www.halliburton.com/public/cem/contents/Data_Sheets/web/H/H07335-BHKA-Tool.pdf
[Accessed 21 Feb. 2018].
Ismail, Z., Kong, K.K., Othman, S.Z., Law, K.H., Khoo, S.Y., Ong, Z.C. and Shirazi, S.M.,
2014. Evaluating accidents in the offshore drilling of petroleum: Regional picture and reducing
impact. Measurement, 51, pp.18-33.
Landucci, G., Argenti, F., Tugnoli, A. and Cozzani, V., 2015. Quantitative assessment of safety
barrier performance in the prevention of domino scenarios triggered by fire. Reliability
Engineering & System Safety, 143, pp.30-43.

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Paik, J.K., Czujko, J., Kim, B.J., Seo, J.K., Ryu, H.S., Ha, Y.C., Janiszewski, P. and Musial, B.,
2011. Quantitative assessment of hydrocarbon explosion and fire risks in offshore installations.
Marine Structures, 24(2), pp.73-96.
Safina, C., 2011. The 2010 Gulf of Mexico oil well blowout: A little hindsight. PLoS biology,
9(4), p.e1001049.
Saleh, J.H. and Pendley, C.C., 2012. From learning from accidents to teaching about accident
causation and prevention: Multidisciplinary education and safety literacy for all engineering
students. Reliability Engineering & System Safety, 99, pp.105-113.
Skogdalen, J.E., Utne, I.B. and Vinnem, J.E., 2011. Developing safety indicators for preventing
offshore oil and gas deepwater drilling blowouts. Safety science, 49(8-9), pp.1187-1199.
Vinnem, J.E., 2013. Offshore risk assessment: principles, modelling and applications of QRA
studies. Springer Science & Business Media.
Xue, L., Fan, J., Rausand, M. and Zhang, L., 2013. A safety barrier-based accident model for
offshore drilling blowouts. Journal of loss prevention in the process industries, 26(1), pp.164-
171.

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Appendix
1. Piper Alpha (1988) [source: BBC News 2018]
2. Macondo Blowout (2010) [source: Bryant 2018]