Thursday, December 12, 2019
Deepwater Horizon Bop Materials Failure Ã¢â¬ Myassignmenthelp.Com
Question: Discuss About The Deepwater Horizon Bop Materials Failure? Answer: Introducation BP Deepwater Horizon Oil Spill was the worst oil spill to have ever happened in the history of the U.S. The disaster started on April 20, 2010. Methane gas started expanding from the well into the drilling riser then streamed into the drilling rig. After accumulating in the drilling rig, it built up excess pressure and heat that ignited the methane gas and caused an explosion. The blowout preventer (BOP) was not able to seal the rig resulting to massive oil spill into the Gulf of Mexico. From the investigations done, it was found that the rigs drill pipe had buckled inside the BOP. A BOP has a hydraulic device (known as blind shear ram) comprising of two cutting blades that are specially designed to be used during an emergency (U.S. Chemical Safety Board, 2014). The cutting blades are intended to cut the drill pipe so as to stop oil from flowing into the rig from the well thus preventing accumulation of the oil in the rig. The BOP also has a cap that is meant to shut off (seal) the w ell thus preventing the oil in the rig from spilling. Therefore the disaster occurred because the BOP failed to perform its intended function. The buckling of the drill pipe was as a result of a mechanism referred to as effective management. This mechanism occurs when the pressure difference between the inside of drill pipe and outside is large. It was also found that the BOP had a dead battery and faulty wiring, which affected the operation of the BOP by failing to activate the BOPs blind shear ram. Background on Operations At the time of the disaster, the Deepwater Horizon had operated for about a decade as a drilling rig. The rig was designed to operate in water up to 3 km deep. Deepwater Horizon was owned by BP, the rig was operated by Transocean and built by Hyundai Heavy Industries, a South Korean firm. When the disaster occurred, the rig was drilling an exploratory well about 5.6 km below the sea level. The rig is located in Macondo Prospect of the Gulf of Mexico. A few days before the accident, operators of the rig noticed an unusual increase in pressure inside the rig. As a result, they cemented the well so as to seal it temporarily (Pallardy, 2017). They performed several pressure tests and unfortunately misinterpreted the results that showed that the well had been sealed properly (Mullins, 2010). The buckling of the BOPs drill pipe on the day the disaster occurred was caused by effective compression. It meant that pressure continued accumulating in the rig without the operators knowing. A few minutes before the explosion, the crew closed the blind shear rams of the BOP at its wellhead to seal the well temporarily. However, this created a rapid increase in pressure difference between the inside of the drill pipe and the outside, causing it to buckle (Offshore Energy Today, 2014). The buckling caused the steel drill pipe to bend outside making it difficult for the BOP to seal the well. An investigation done on the disaster found that safety systems of the rigs blowout preventer (BOP) were not tested properly thus exposing the entire oil rig to risks of failure. This happened despite the manufacturer of the BOP having recommended that individual tests be performed on the safety systems by the owner and operator of the rig (Associated Press, 2014). A BOP is an emergency device and therefore has to be tested regularly to ensure that it is in proper working condition. It is also important for oil rig operators to collect real-time data of various components of the rig so as to identify if they exhibit any unusual behaviors and take necessary and timely actions to prevent potential risks. Background on the Operating Environment When Deepwater Horizon oil spill occurred, the rig had 126 crew members: 79 Transocean employees, 7 BP employees and 40 employees of different companies. There was an uncontrolled flow of methane gas, oil mud, water, and other materials from the well into the rig through the drilling riser and rill pipe. This accumulation caused the drill pipe to buckle resulting to explosion of the entire drilling rig. The explosion, which burnt for two consecutive days killed 11 workers, making it the worst oil spill in the history of the U.S. (Meigs, 2016). It is estimated that 780,000 m3 of oil leaked into the Gulf of Mexico for 87 consecutive days, which made it the biggest oil spill to have ever occurred in the U.S. history (Adams and Gabbatt, 2011; EnerKnol Research, 2015; Office of Response and Restoration, 2017). Spilling of oil continued from April 20, 2010 until July 15, 2010 when the well was capped (U.S. Environmental Protection Agency, 2017). The spill have had devastating effects on aq uatic life, birds, tourism, and both people and environment along Louisiana coastline (Sherwell, 2015). Having operated for a decade without experiencing any serious tragedy, BP and Transocean were overconfident about their oil drilling operations. As a result of this, most of their proposals were usually rubber-stamped by the federal regulators. They continued drilling into very deep waters and dug wells involving high internal pressures and risks. The regulations and technologies that were being used during those days did not commensurate the risks, which many drillers did not have measures to prevent or mitigate them. One of the strategies that drillers use as a last-ditch protection against blowing out of an oil well from high-pressure gases is installation of a BOP. BOPs are usually fastened on top of subsurface wells, as shown in Figure 1 below (Aeberman, 2010). These devices are used during emergencies as last options to contain the situation (Gold, 2014). They use different mechanisms, including shears and clamps, to try and seal the well so as to prevent or stop oil from flowing up the drill pipe and possibly disconnect the well from the rig. The BOPs can either be operated manually or automatically when electricity or pressure is cut off. The BOP that was being used in Deepwater Horizon was 9 years old. It was about 17.4 m tall and weighed approximately 400 tons (Associated Press, 2014). Figure 1: Schematic diagram of an oil well and rig The design of BOPs is supposed to aim at Accounting a component that can make the drill pipe more stable and prevent leaks. However, BP did not prioritize this instead it decided to go for the quickest design approaches rather than the most secure methods. For instance, it was found that BP chose to modify its BOP in China instead of the U.S. so as to save costs (Web, 2010). BP also made several other time- or cost-saving decisions without analysis their risk implications (Brooder, 2011a; Zolkos and Bradford, 2011). The manufacturer of the BOP, Cameron International, had even suggested that BP performs safety tests on the BOP components but this was not taken seriously by the company. There was a time when the crew conducted two essential pressure tests to ascertain the integrity of the well. They obtained very worrying and confusing results from the first test. When they conducted the second test with a different pipe, the results they obtained are what they wanted. So they disregar ded the first results and used the second results to conclude that the well was operating properly. In general, Deepwater Horizon was operating in very deep water where pressure was extremely high. The drill pipe was made of steel, which is susceptible to buckling when subjected to high pressure differences. The steel drill pipe used was designed for normal water pressures but BP continued drilling deeper without considering the structural integrity and soundness of the drill pipe. As expected, the high pressure difference in the deep water caused the steel drill pipe to buckle, which played a role in failure of the BOP causing the oil rig to explode. When operating in such environments, it is important to use real-time data and calculate the stresses caused by the pressure on the drill pipe so as to determine its capacity to function as expected. If this was done, it is likely that the steel drain pipe would have failed integrity test thus finding alternative materials or design of the component. In addition, such operating environments also necessitates frequent checks of safety systems of the rig and well. Had this been done, it is likely that safety systems of the BOP would have been determined to be insufficient hence necessary actions would be taken to prevent or mitigate possible risks. Therefore the steel drill pipe was operating in an environment with very high pressure that caused it to buckle thus compromising its structural integrity and functionality. Provide an analysis of the failure modes and potential causes of failure based on an extensive review of literature Failure analysis entails use of different approaches to establish possible causes of failure of a system or component. It is very important to conduct a comprehensive failure analysis so as to prevent similar failures in the future by developing or suggesting improvements in the design, manufacturing, operation and maintenance of the systems or components. Basically, failure analysis focuses on investigating and collecting evidence and identifying any anomalies that may have caused the system or component to fail, develop problems or not perform as expected. This process should only be completed after identifying the root cause of the failure. For instance, a manufacturer can produce a component with flaws that can cause it to fail. However, it is important to look at the reasons or factors that contributed to the manufacturing flaws? Were they because of poor design, poor quality of materials, imprecise machine or computer systems, or improper supervision? These are now the root cau ses of failure of the component, and the process of examining them is referred to as root cause analysis. According to ThinkReliability (2017), root cause analysis involves identifying and scrutinizing underlying causes of a problem with an aim of identifying and implementing effective solutions. Root cause analysis has to be done by following certain principles. Some of these principles are: it should aim at identifying factors that contributed to the problem, determine necessary changes that will prevent reoccurrence of these problems at the lowest cost and establish lessons learnt from the problems; and it must be effective and carried out systematically. Root cause analysis also has to be performed by following certain steps. These are: defining the problem, collecting data and evidence, asking reasons for the failure and identifying the real root causes, identifying corrective actions, identifying effective solutions, implementing recommendations, observing the impact of implemented recommendations, and addressing any other challenges that may arise (Hubbard, 2010). There are also d ifferent techniques of root cause analysis, such as: barrier analysis, change analysis, causal factor tree analysis, Bayesian inference, current reality tree, fault tree analysis, Pareto analysis, 5 whys, etc. Root causes of problems or defects can also be put into various groups, including: design flaw, material defect, manufacturing defect, installation defect, operational defect, maintenance defect, unforeseen occurrences. Design flaws are those caused by inadequate design of the system or component. Material defects results from use of poor quality materials or inappropriate material selection. Manufacturing defects are caused by wrong manufacturing procedures. Installation defects are caused by following incorrect installation procedures of the systems. Operational defects result from improper use of the system. Maintenance defects occurs when the system is not maintained as recommended by the manufacturer. Lastly, unforeseen causes are those resulting from unexpected natural occurrences such as earthquakes or tsunamis. Root causes or evidences can be collected through video footages, physical observations or witness interviewing. These methods provide investigators with adequate investigation to start and complete the investigation this helps them to identify possible failure modes that caused the problem. A failure mode is simply a way in which a component may fail to perform its function adequately (American Society for Quality, 2017). Examples of failure modes are brittle fracture, ductile fracture, fatigue, buckling, yielding, creeping, corrosion, wear, thermal shock, excessive deflection, etc. These failure modes can be as a result of design weaknesses or faults, manufacturing faults, operation errors or maintenance mistakes. In Deepwater Horizon oil spill, the disaster occurred because of blind shear rams failing to close the shut off the well (Flow Control, 2011). The failure of the blind shear rams was caused by buckling of the drill pipe that forced the blind shear rams to be positioned off center to the cross section of the drill pipe. Therefore the failure mode in the accident was buckling and it was caused by design faults, operation mistakes and maintenance errors. Buckling is a type of failure mode that occurs when a structural component loses stability due to the load applied on it (Akin, 2010). According to Cyprien (2017), this failure mode is very dangerous as it can happen even before the material reaches its yielding point. Occurrence of buckling is usually related to slenderness ration i.e. ratio between the height of the component and its radius. In this case, the slenderness ratio was very high people the length of the drain pipe was very big compared to other dimensions such as radius. T herefore the drain pipes lateral dimensions were weak, making it disposed to buckling. The failure mode in Deepwater Horizon was caused by design faults because the design team did not comprehensively evaluate the behavior of the steel component when subjected to large pressure differences, which was a major possibility. If the design team had performed comprehensive analysis of the steel drill pipe, they would probably have known that steel used was not the most suitable material for that purpose. Therefore the steel material of drill pipe failed by buckling because it was not suitable for the intended use. Another cause of failure mode in the accident was operation faults. This is because of the decisions that were made concerning the oil rig operations. There were two main operation faults that are likely to have resulted to the failure modes. The first one is failure of the cementing process that had been done at the wells base to contain gas and oil inside the wellbore (Brooder, 2011b). The operator of the rig decided to cement the well for the purposes of sealing it temporarily. However, the cementing was not done properly and as a result the well started leaking. The crew carried out pressure tests to confirm if the well had been sealed properly but they misinterpreted the results. The leaking continued and led to accumulation of pressure in the well, which again contributed to buckling of the drill pipe that caused the rig to explode. Another operation mistake that resulted to the failure mode was negligence of the rig operators. According to Carole (2016), there were 2 mechanical valves that failed to prevent flow of oil and gas up to the surface of the well. However, the operators did not take necessary actions to repair or replace the valves. As a result, the gas started leaking inside the well leading to rapid increase in pressure. The operators also did not detect it the leakage, which is an operation mistake because it means they were not monitoring the operations thoroughly. This gas leakage, and failure of cement and valves caused pressure inside the drill pipe to increase rapidly than outside, creating very high pressure difference and compressive stress inside the pipe. This caused the steel drill pipe to buckle. The buckling meant that the BOP could not perform its intended function because the buckled drill pipe prevented the blind shear rams from sealing the well. The gas detection system that would h ave sounded an alarm was not functional and the BOP had a dead battery and wiring problem that prevented it from automating its safety system. As a result of all these, the methane gas flowed up the well, reached the drilling rig, got ignited and explored. Another cause of failure mode in this accident was maintenance mistakes. Having identified some defaults in the BOP, BP chose to rectify them in China and not the U.S. This decision was made so as to save time and money. This compromised the structural integrity of the BOP because during that time, there were no specialized companies in China that could comprehensively evaluate the BOP and identify and rectify all possible failures. If the BOP had been taken to the U.S. for rectification, there is a possibility that the unsuitability of steel drill pipe would have been identified and corrected thus preventing the disaster. Review and critique one of the failure report as prepared by the experts; comment specifically on whether the methodology is suitable and adequate based on your extensive review of literature The interim report released by the National Research Council (NRC) and National Academy of Engineering (NAE) focused on investigating the causes of the Deepwater Horizon oil spill and how similar events can be prevented in the future. The committee formed by the two agencies collected information from different private and government organizations, made site visits, observed enquiries that were led by the Marine Board of Inquiry, and evaluated written information. The report comprises of several sections, each discussing different issues. The first section contains summary of preliminary observations and findings by the committee. The second section discusses cementing operations carried out on the well. The subsections here include well characteristics, long string limitations, cementing process that was used, and float equipment and shoe track. The third section contains information about flawed cement job indications and how the flow started. Specific areas discussed are negative- pressure test and monitoring services of the well. The fourth section of the report is well control actions. This has discussed the actions that the Deepwater Horizon personnel took to control the well after methane gas and other materials had started flowing. The key areas discussed are flow diversion and BOP. The fifth section discussed the Deepwater Horizons gas detection systems, alarms and safety systems (National Academy of Engineering and National Research Council, 2010). The sixth section contains information about operational management. It has analyzed how decision making was delegated to different authorities, standards for training, education and professional qualification of personnel, h9ow the management used real-time data, integration of schedule, cost and safety responsibilities, and what was learnt from experiences. The seventh section of the report is oversight regulation. This discusses oversight personnels qualifications, different regulatory authorities and th eir responsibilities, standards development, and independent assessment of well completion procedures and essential safety equipment. The last section of the report states on how the committee intends to complete the study and prepare the final report. Even though this report contains most of the key areas that should be investigated so as to identify the actual happenings that led to the oil spill, it does not provide specific information on how this should be done. The methodology used in the report is much generalized making it difficult to make specific findings and observations. Despite having recognized the function and relevance of BOP in sealing wells during emergencies, the committee did not examine the device nor did it interview Transocean or Cameron International representatives on the same. The report was released before the committee could analyze the technical drilling data it had requested. Therefore it does not identify any specific failure mechanism that led to the explosion of Deepwater Horizon. The report does not specify the path that hydrocarbons followed from the well into the rig, causing it to explode. Also, the report does not make any recommendations on how similar events can be avoided in the future yet it was one of its main objectives. Therefore the methodology used in preparing this report is not sufficient because it only identified areas of concern that require comprehensive analyses. Comment on whether additional information or additional investigation is required (e.g. sample testing or validation required) There is a lot of additional information and investigation required in this interim report. The committee found that the BOP failed to seal the well and therefore several tests need to be performed so as to establish the failure modes of the component. The BOP was made of steel and therefore further investigations should be done to know its failure mechanism. All failed components need to tested to ascertain whether they met their design specifications. Besides that, manufacturing processes of these components should also be reviewed. Having received the technical drilling data, the committee should analyze it comprehensively so as to understand the operation and behavior of the well before the disaster. This will help in identifying some of the causal factors of the components failure and well blowout. For instance, it will provide information on the hydrocarbon pathway and the increase in pressure within the well. It is also important for the committee to interview all agencies and representatives involved in the manufacturing, construction, operation and maintenance of the well and rig. Professional certification of personnel, testing procedures of components and the well, oversight authorities, regulatory policies, and maintenance procedures related to the drilling operations also need to be appraised. In general, the committee has to focus on identifying the root cause(s) of the disaster so as to establish appropriate ways of preventing such disasters in the future. Recommend suitable solutions or rectification to the problem (based on certain assumptions) The first solution is to review the design process of all drilling components. It is very important for the design teams to comprehensively evaluate the behavior of materials used to fabricate these components by considering their working environments and strictly advise manufacturers and users the range of conditions within which the components should be used. The designers and manufacturers should review their quality control strategies so as to ensure that the components manufactured meet the required design specifications and functional requirements. These components should be designed accurately, manufactured using proper procedures and methods, and tested comprehensively before being sold. If this was done then the same BOP and other components such as drill pipe could not be used when the rig operator decided to drill at deeper depths, which were probably higher than the depth range recommended for the components. This is because does so would be loading the component material s beyond their working capacity. It is important for companies to follow manufacturers instructions and recommendations when using their components. For instance, they need to test the components, if recommended so, and also continuously check and monitor their performance. If BP and Transocean had followed the recommendations by Cameron International to test the BOP before installing it then it is likely that the unsuitability of steel drill pipe would have been identified and marketing. It is also important for drilling companies to maintain their oil rigs properly so as to identify any problem before it gets out of hand. All drilling operations must be done in accordance with federal and state regulations and policies. Personnel involved in the operation and maintenance of the drilling rig must possess the right professional certifications. The gas leakage would have been noticed if personnel involved in the operations had the right qualifications in terms of knowledge and experience on oil rig operations. Additionally, drilling rig owners and operators must always consider safety implications of their decisions. For instance, if they decide to drill deeper into the waters, they should analyze how the increased depth will affect the performance of rig components. Last but not least, it is very important to collect technical data of the drilling rig operations and analyze it thoroughly so as to know the behavior of all components and identify any anomalies. If this was done, the crew would have noticed abnormal pressures and probably taken actions to prevent uncontrolled pressure increase in the well, which resulted to buckling of drill pipe and failure of the BOP. Materials Selection Provide an outline and analysis of the performance requirements Material selection process is a very important process as it ensures that the product designed and manufactured is able to perform its intended function perfectly (Ehinger et al., 2015). A drill pipe is a hollow piping that is used for transmitting oil, gas and other fluid materials from the well into the rig (DrillingFormulas.com, 2013; Flowtech Energy, 2016). This component work in uncontrolled flow and high-pressure conditions, which expose it to wear, tear and fatigue risks (Keystone Energy Tools, 2015; Pusca, 2015; Spoerker, Havlik and Jellison, 2009). The component is very useful in preventing a blowout. When the flow of gas or oil starts getting out of control, blind shear rams of the BOP are used to cut the drill pipe so as to stop the oil or gas from flowing up the well. Therefore this component must meet certain performance requirements, which include the following: Superior stiffness properties this prevents the component from deflecting and buckling when exposed to high loads such as pressures and vibrations. High pressure resistance the component must be able to remain stable even when subjected to high internal and external pressures High thermal resistance the component should withstand high heat conditions and maintain its strength Excellent fatigue properties since the component functions continuously, it should have great fatigue properties throughout its service life High vibration resistance the component work by rotating and lifting other components of the drilling rig. Therefore it should be able to withstand high vibrational forces Machinability/fabricability it should also be easy to machine and fabricate so as to attain precise designs for it to fit into other components properly Corrosion and erosion resistance since oil, gas and other fluids flow through the drill pipe, it should be able to resist corrosion and erosion cause by these fluids so as to maintain its structural soundness Lightweight (thickness) it should also be of appropriate thickness and weight Durability the component should also be long lasting to reduce frequent maintenance, repairs or replacements. Cost the cost of the component should be reduced as much as possible but without reducing or compromising its quality and performance Evaluate and select an appropriate materials selection method Therefore this method can be used to find alternative materials for steel drill pipe. In other words, steel will be used as datum. The main focus is to select a material that has high stiffness, fatigue resistance, thermal resistance, pressure resistance, machinability, vibration resistance, durability, corrosion and erosion resistance, and low cost. Based on these criteria, some materials can be eliminated from the selection process because they do not meet most of these requirements. The materials that wont be considered are: ceramics, polymers, wood, glass, foams and rubbers. Therefore materials that can be considered are metals, metal alloys and composites. Use of charts is very important in narrowing down the list of possible alternatives. Since the steel drill pipe failed due to buckling, the selection method will focus on choosing a material that has superior buckling or stiffness properties than steel. Systematically justify your selection of materials for the equipment A material with superior stiffness properties is the one that does not deform easily (Burnett, 2016). Several studies have been done to identify alternative materials to steel for making drill pipes. The most common alternatives that have been identified are titanium and aluminium alloys, and polymer-based composites (Bensmina, Menand and Sellami, 2011; Erling, 2012; Falther, 2017). These materials have similar properties as steel, and are preferred alternatives because of their lightweight and superior buckling resistance (Ahmet and Zehra, 2015; Arconic, 2017; Vadim, 2011; Wang, 2016). From Figure 2 below, aluminium titanium alloys and polymer-based composites are some of the metals that yield before they fracture. This is a very important property because it will have prevented the problem that occurred in Deepwater Horizon disaster, where the steel drill pipe buckled before reaching its yield strength. Figure 2: Youngs modulusdensity of different materials (Source: https://sites.google.com/site/me122bikehubdynamo/hardware-implementation/electrical-hardware/mechanical-hardware?tmpl=%2Fsystem%2Fapp%2Ftemplates%2Fprint%2FshowPrintDialog=1) As stated before, mechanical and physical properties of these two materials are very similar to those of steel. For aluminium, its strength-to-weight ratio is greater than that of steel (Clarke, 2016). Therefore the Pugh matrix of the alternatives is as shown in Table 1 below Table 1: Pugh Matrix of the alternatives Criteria Steel (current material) Alternative 1 (Aluminium alloy) Alternative 2 (Titanium alloy) Polymer-based composite Stiffness Datum +1 +2 Pressure resistance Datum +2 +2 +3 Thermal resistance Datum -2 -1 -1 Fatigue properties Datum +1 +2 +2 Vibration resistance Datum 0 0 0 Machinability Datum +1 0 +2 Corrosion and erosion resistance Datum 0 +1 +1 Lightweight (thickness) Datum +4 +3 +5 Durability Datum -1 0 -3 Cost Datum +5 -5 -5 3 6 9 14 10 13 Resultant 11 4 4 From Table 1 above, the most suitable alternative for the component is aluminium alloy. This material has shown the likelihood of meeting the performance requirements of drill pipe. The main advantage of metal alloys and composites is that their composition can be modified so as to achieve desired performance requirements of the product. Nevertheless, the exact composition of aluminum alloy can only be determined if more specific data about the performance requirements is provided. Comment on whether additional information or additional investigation is required The need for additional investigation or information is rather obvious. It is mandatory for the recommended material to be tested in the lab so as to attest its mechanical and physical properties. Computer simulations should also be created to analyze and understand the behavior of the material under different conditions. It is better to manufacture a prototype drill pipe using the recommended material and then subject it to various tests including tensional, fabricability, compressional, fatigue, and other appropriate stress tests. This will help in ascertaining or attesting the suitability of the material to meet the various performance requirements in the Pugh Matrix. Approximate durability and cost of the material should also be determined. Recommend suitable materials for the shut-off valve (based on certain assumptions) From the extensive literature review done, the most suitable material for the shut-off valve is aluminium alloy. This material combines most of the performance criteria or requirements. Since the component functions in an environment that has high and fluctuating pressures, buckling resistance or stiffness properties is a very crucial variable. Aluminium alloys have good stiffness properties and therefore this component will not fail before yielding as it was the case for steel. Another great advantage of aluminium alloy is that its composition can be adjusted so that the material can function perfectly in an environment with high pressure, temperature, fatigue, vibration, corrosion and erosion. The material is also easy to fabricate, is durable, lightweight and its cost is very low compared to steel and other alternatives. Therefore aluminium alloy is the most suitable material for shut-off valve and its exact composition will be determined by the test results obtained and the perfo rmance requirements. References Adams, R. and Gabbatt, A. (2011) BP oil spill report as it happened [Online] The Guardian. Available: https://www.theguardian.com/environment/blog/2010/sep/08/bp-oil-spill-report-live [Accessed May 13, 2017]. Aeberman (2010) What caused the Deepwater Horizon disaster? [Online]. Available: https://www.theoildrum.com/node/6493 [Accessed May 13, 2017]. Ahmet, Y.O. and Zehra, O.B. (2015) Integrating superficially treated 2014 aluminium alloy in steel drill string to deal with fatigue problem in crooked trajectory for vertical deep well. Proceedings of 3rd International Congress on Energy Efficiency and Energy Related Materials, 19-23 October, 2015, Oludeniz, Turkey. Akin, J.E. (2010) Concepts of buckling [Online]. Available: https://www.clear.rice.edu/mech403/HelpFiles/Buckling_Concepts.pdf [Accessed May 13, 2017]. American Society for Quality (2017) Failure mode effects analysis (FMEA) [Online]. Available: https://asq.org/learn-about-quality/process-analysis-tools/overview/fmea.html [Accessed May 13, 2017]. Arconic (2017) The strength of steel at half the weight [Online]. Available: https://www.arconic.com/global/en/products/info_page.asp?prod_id=4052info_page_id=916 [Accessed May 14, 2017]. Associated Press (2014) Investigation into 2010 BP oil spill finds failures, poor testing and ongoing risks [Online] The Guardian. Available: https://www.theguardian.com/environment/2014/jun/05/bp-deepwater-horizon-spill-report-failures-risks [Accessed May 13, 2017]. Bensmina, S., Menand, S. and Sellami, H. (2011) Which drill is the less resistant to buckling: steel, aluminium or titanium drill pipe? Texas, USA: Society of Petroleum Engineers. Brooder, J.M. (2011a) Blunders abounded before Gulf spill, panel says [Online] The New York Times. Available: https://www.nytimes.com/2011/01/06/science/earth/06spill.html [Accessed May 13, 2017]. Brooder, J.M. (2011b) BP shortcuts led to Gulf oil spill, report says [Online]. The New York Times. Available: https://www.nytimes.com/2011/09/15/science/earth/15spill.html [Accessed May 13, 2017]. Burnett, C. (2016) Metal strength and stiffness: whats the difference? [Online]. Available: https://www.thermofisher.com/blog/metals/metal-strength-and-stiffness-whats-the-difference/ [Accessed May 14, 2017]. Carole, B. (2016) What caused the Deepwater Horizon explosion? [Online] AwesomeStories.com. Available: https://www.awesomestories.com/asset/view/What-Caused-the-Deepwater-Horizon-Explosion- [Accessed May 13, 2017]. Clarke, R. (2016) The weight is over: aluminium in the oilfield [whitepaper] [Online]. Available: https://oilpro.com/post/3460/the-weight-is-over-aluminum-in-the-oilfield-white-paper [Accessed May 14, 2017]. Cyprien (2017) Failure modes: understand the 5 most Business failure types [Online]. Available: https://feaforall.com/failure-modes/# [Accessed May 13, 2017]. Decision-Making-Confidence.com (2016) How to use the Pugh Matrix [Online]. Available: https://www.decision-making-confidence.com/pugh-matrix.html [Accessed May 14, 2017]. DrillingFormulas.com (2013) Basic understanding about drill pipe [Online]. Available: https://www.drillingformulas.com/basic-understanding-about-drill-pipe/ [Accessed May 14, 2017]. Ehinger, D., Kruger, L., Martin, U., Weigelt, C. and Aneziris, C.G. (2015) Buckling and crush resistance of high-density TRIP-steel and TRIP-matrix composite honeycombs to out-of-plane compressive load. International Journal of Solids and Structures, vol. 66, no. 1, pp. 207-2017. EnerKnol Research (2015) New offshore oil regulations respond to key failures of Deepwater Horizon Spill [Online] Breaking Energy. Available: https://breakingenergy.com/2015/04/27/new-offshore-oil-regulations-respond-to-key-failures-of-deepwater-horizon-spill/ [Accessed May 13, 2017]. Erling, G. (2012) The use of alternative materials for drill pipe to extend drilling reach in shallow reservoirs. Thesis (Masters Degree), University of Stavanger. Falther, S. (2017) Alternative materials in the oil and gas sector [Online]. Available: https://www.offshoreenergy.dk/offshoreenergy/press/on-off-magazines/articles/alternative-materials-in-the-oil-and-gas-sector.aspx [Accessed May 14, 2017]. Flow Control (2011) What caused the Deepwater Horizon explosion oil spill? [Online]. Available: https://www.flowcontrolnetwork.com/what-caused-the-deepwater-horizon-explosion-oil-spill/ [Accessed May 13, 2017]. Flowtech Energy (2016) What is a drill pipe? [Online]. Available: https://www.flowtechenergy.com/oil-gas-questions/drill-pipe/ [Accessed May 14, 2017]. Gold, R. (2014) Deepwater Horizon oil spill linked to failed blowout preventer [Online]. Available: https://www.wsj.com/articles/investigators-fault-blowout-preventer-in-deepwater-horizon-oil-spill-1401984643 [Accessed May 13, 2017]. Hubbard, B. (2010) Root Cause Analysis (Overview) [Online]. Available: https://bobsleanlearning.wordpress.com/2010/09/16/root-cause-analysis-overview/ [Accessed May 13, 2017]. iSixSigma (2017) Pugh Matrix [Online]. Available: https://www.isixsigma.com/dictionary/pugh-matrix/ [Accessed May 14, 2017]. Keystone Energy Tools (2015) Important facts about your drill pipe [Online]. Available: https://keystoneenergytools.com/blog/important-facts-about-your-drill-pipe [Accessed May 14, 2017]. Lugo, J.E. (2012) Pugh method: how to decide between different designs? [Online]. Available: https://sites.nd.edu/jlugo/2012/09/24/pugh-method-how-to-decide-between-different-designs/ [Accessed May 14, 2017]. Management Study Guide Experts (2017) What is Pugh matrix and how to use it? [Online]. Available: https://www.managementstudyguide.com/pugh-matrix.htm [Accessed May 13, 2017]. Meigs, J.B. (2016) Blame BP for Deepwater Horizon but direct your outrage to the actual mistake [Online]. Available: https://www.slate.com/articles/health_and_science/science/2016/09/bp_is_to_blame_for_deepwater_horizon_but_its_mistake_was_actually_years.html [Accessed May 13, 2017]. Miller, C.D. (n.d.) Pugh method or decision-matrix method [Online]. Available: https://staff.adams.edu/~cdmiller/cs-arch/pugh_method.htm [Accessed May 14, 2017]. Mullins, J. (2010) The eight failures that caused the Gulf oil spill [Online] New Scientist. Available: https://www.newscientist.com/article/dn19425-the-eight-failures-that-caused-the-gulf-oil-spill/ [Accessed May 13, 2017]. National Academy of Engineering and National Research Council (2010) Interim report on causes of the Deepwater Horizon oil rig blowout and ways to prevent such events. Washington, DC: U.S. Department of Interior. Office of Response and Restoration (2017) Deepwater Horizon Oil Spill [Online]. Available: https://response.restoration.noaa.gov/oil-and-chemical-spills/significant-incidents/deepwater-horizon-oil-spill [Accessed May 13, 2017]. Offshore Energy Today (2014) Pipe buckling caused Deepwater Horizon disaster, U.S. CBS says [Online]. Available: https://www.offshoreenergytoday.com/pipe-buckling-caused-deepwater-horizon-disaster-u-s-csb-says/ [Accessed May 13, 2017]. Pallardy, R. (2017) Deepwater Horizon oil spill of 2010 [Online]. Available: https://www.britannica.com/event/Deepwater-Horizon-oil-spill-of-2010 [Accessed May 13, 2017]. Pusca, A. (2015) Understanding the inspection process of drilling tubulars [Online]. Available: https://blog.odfjellwellservices.com/understanding-the-inspection-process-of-drilling-tubulars [Accessed May 14, 2017]. Sherwell, P. (2015) BP oil spill: five years after worst environmental disaster in US history, how bad was it really? [Online] The Telegraph. Available: https://www.telegraph.co.uk/news/worldnews/northamerica/usa/11546654/BP-oil-spill-Five-years-after-worst-environmental-disaster-in-US-history-how-bad-was-it-really.html [Accessed May 13, 2017]. Spoerker, H., Havlik, W. and Jellison, M. (2009) What really happens to high-strength drill pipe after exposure to sour gas environment? [Online]. Available: https://www.drillingcontractor.org/what-really-happens-to-high-strength-drill-pipe-after-exposure-to-sour-gas-environment-1636 [Accessed May 14, 2017]. Tague, N.R. (2017) Decision matrix [Online]. Available: https://asq.org/learn-about-quality/decision-making-tools/overview/decision-matrix.html [Accessed May 14, 2017]. ThinkReliability (2017) Root cause analysis explained [Online]. Available: https://www.thinkreliability.com/root-cause-analysis-explained/ [Accessed May 13, 2017]. U.S. Chemical Safety Board (2014) CBC Releases New computer Animation of 2010 Deepwater Horizon Blowout [Online]. Available: https://www.csb.gov/csb-releases-new-computer-animation-of-2010-deepwater-horizon-blowout/ [Accessed May 13, 2017]. U.S. Environmental Protection Agency (2017) Deepwater Horizon BP Gulf of Mexico Oil Spill [Online]. Available: https://www.epa.gov/enforcement/deepwater-horizon-bp-gulf-mexico-oil-spill [Accessed May 13, 2017]. Vadim (2011) KUMZ has developed new aluminium alloy for drill pipes [Online]. Available: https://www.rusmininfo.com/news/16-06-2011/kumz-has-developed-new-aluminium-alloy-drill-pipes [Accessed May 14, 2017]. Wang, V. (2015) What advantages does aluminium alloy drilling pipe have? [Online]. Available: https://www.linkedin.com/pulse/what-advantages-does-aluminum-alloy-drilling-pipe-have-vicky-wang [Accessed May 14, 2017]. Web, T. (2010) BP oil spill: failed safety device on Deepwater Horizon rig was modified in China [Online]. Available: https://www.theguardian.com/environment/2010/jul/18/deepwater-horizon-blow-out-preventer-china [Accessed May 13, 2017]. Zolkos, R. and Bradford, M. (2011) BP disaster caused by series of risk management failures, according to federal investigation of Gulf spill [Online]. Available: https://www.businessinsurance.com/article/20110918/NEWS06/309189982/BP-disaster-caused-by-series-of-risk-management-failures,-according-to-federal-i [Accessed May 13, 2017].