Experimental evaluation of an electro-Hydrostatic actuator for subsea applications in a hyperbaric chamber

A novel Electro-Hydrostatic Actuator (EHA) prototype – designed to operate on subsea gate valves in deep and ultra-deep water – is analysed and qualified in terms of functionality under design and normative constraints. The prototype is assembled in a test bench for load control in a hyperbaric chamber where the high subsea environmental pressure can be emulated. The process variables under evaluation are monitored through a set of pressure and position sensors, which are part of the prototype design. The experimental results demonstrate a robust behaviour of the actuator concerning the imposed external pressure and load forces even with a forced limitation in its power input. Moreover, the prototype performs consistently throughout the entire endurance trial, asserting high reliability. With the results obtained, the subsea EHA concept is effectually eligible to a technology readiness level 4, according to the API 17N

Development of an ontology supporting failure analysis of surface safety valves used in Oil & Gas applications

Treball desenvolupat dins el marc del programa 'European Project Semester'.The project describes how to apply Root Cause Analysis (RCA) in the form of a Failure Mode Effect and Criticality Analysis (FMECA) on hydraulically actuated Surface Safety Valves (SSVs) of Xmas trees in oil and gas applications, in order to be able to predict the occurrence of failures and implement preventive measures such as Condition and Performance Monitoring (CPM) to improve the life-span of a valve and decrease maintenance downtime. In the oil and gas industry, valves account for 52% of failures in the system. If these failures happen unexpectedly it can cause a lot of problems. Downtime of the oil well quickly becomes an expensive problem, unscheduled maintenance takes a lot of extra time and the lead-time for replacement parts can be up to 6 months. This is why being able to predict these failures beforehand is something that can bring a lot of benefits to a company. To determine the best course of action to take in order to be able to predict failures, a FMECA report is created. This is an analysis where all possible failures of all components are catalogued and given a Risk Priority Number (RPN), which has three variables: severity, detectability and occurrence. Each of these is given a rating between 0 and 10 and then the variables are multiplied with each other, resulting in the RPN. The components with an RPN above an acceptable risk level are then further investigated to see how to be able to detect them beforehand and how to mitigate the risk that they pose. Applying FMECA to the SSV mean breaking the system down into its components and determining the function, dependency and possible failures. To this end, the SSV is broken up into three sub-systems: the valve, the actuator and the hydraulic system. The hydraulic system is the sub-system of the SSV responsible for containing, transporting and pressurizing of the hydraulic fluid and in turn, the actuator. It also contains all the safety features, such as pressure pilots, and a trip system in case a problem is detected in the oil line. The actuator is, as the name implies, the sub-system which opens and closes the valve. It is made up of a number of parts such as a cylinder, a piston and a spring. These parts are interconnected in a number of ways to allow the actuator to successfully perform its function. The valve is the actual part of the system which interacts with the oil line by opening and closing. Like the actuator, this sub-system is broken down into a number of parts which work together to perform its function. After breaking down and defining each subsystem on a functional level, a model was created using a functional block diagram. Each component also allows for the defining of dependencies and interactions between the different components and a failure diagram for each component. This model integrates the three sub-systems back into one, creating a complete picture of the entire system which can then be used to determine the effects of different failures in components to the rest of the system. With this model completed we created a comprehensive FMECA report and test the different possible CPM solutions to mitigate the largest risks

Requirements Elicitation for Barrier Monitoring System

Master's thesis in Industrial asset managementThe activities undertaken by operator companies in the Norwegian Continental Shelf pose a very high risk to human life and the environment. Leading causes of accidents are poor maintenance, inadequate risk assessment and failure of barrier safety valves. A combination of all the listed accident causes are investigated with a focus on barrier valves (PMV, PWV, DHSV). Despite the fact that PSA has defined regulations and recommended standards related to barriers managements, operators in the Norwegian continental shelf still fail to implement the regulatory requirements regarding safety barriers. This stems from challenges related to interpretation and uncertainty of barrier testing requirements. Challenges related to interpreting barrier requirements arise from terminological inconsistencies or the use of non-standard syntax in documenting requirements. The purpose of this study was to illuminate the challenges encountered by operator companies in adhering to standards recommended by Petroleum Safety Authority of Norway. There will be a focus on clarity of testing requirements from standards, technical challenges which prevent standard adherence and technical capabilities of current condition monitoring systems. To understand how these requirements and generate primary data, semi-structured interviews (with customers or via representative) were performed to get specific clarification and standard based requirements, customer-based requirements are analyzed and verified. Secondary data was also collected and analyzed from di erent case studies. The requirements elicitation discovered that companies preferred to follow NOR-SOK D-10 as opposed to PSAN recommendation of NOG 070, since NOG 070 gives little weight to uncertainties during PFD calculation. Commonest failure modes cited during valve failure were mechanical failure due to leakage, general mechanical failure and corrosion. Findings also suggested that operator companies did not follow the maintenance procedure strictly. Also, condition monitoring systems provided by monitoring service providers did not could not detect certain failure modes that operators faced

Application of SIMULINK to Emulate Subsea Production System (SPS) Control Functions

Subsea control systems in subsea production system (SPS) play a vital role in the safe and productive operation of any oil or gas field. These systems operate in extreme environments, thus making the installation and commissioning the system risky and costly. For a new developer, a better understanding on how the system works is needed to ensure that the system will meet all design specifications and reduce the risk and costs associated with installation and commissioning. Hence, leading oil and gas companies are turning to simulation software where the whole subsea control systems from the Hydraulic Power Unit to the Subsea Control Module can be modeled. This project aims to develop a SIMULINK model for a specific SPS and to assist in ensuring that the system will function accordingly. The scope of the project is to concentrate on the movement of the gate valve in subsea control system where the flow of an oil and gas is controlled. The methodology of the project involves collection of technical details and data regarding subsea control modules, identify elements of the control system, arrangement block diagram notation of the SIMULINK software, the acquisition of the SPS design parameters, and the development of SPS control system equation. Simulation result shows that the gate valve is fully open at 10cm within 0.075s. This will be useful to conduct a sensitivity analysis in the matter of SPS changing key design parameters. Moreover, this project will give lots of advantages to a new developer to understand the system well before developing the actual SPS control system

Multi criteria risk analysis of a subsea BOP system

The Subsea blowout preventer (BOP) which is latched to a subsea wellhead is one of several barriers in the well to prevent kicks and blowouts and it is the most important and critical equipment, as it becomes the last line of protection against blowout. The BOP system used in Subsea drilling operations is considered a Safety – Critical System, with a high severity consequence following its failure. Following past offshore blowout incidents such as the most recent Macondo in the Gulf of Mexico, there have been investigations, research, and improvements sought for improved understanding of the BOP system and its operation. This informs the need for a systematic re-evaluation of the Subsea BOP system to understand its associated risk and reliability and identify critical areas/aspects/components. Different risk analysis techniques were surveyed and the Failure modes effect and criticality analysis (FMECA) selected to be used to drive the study in this thesis. This is due to it being a simple proven cost effective process that can add value to the understanding of the behaviours and properties of a system, component, software, function or other. The output of the FMECA can be used to inform or support other key engineering tasks such as redesigning, enhanced qualification and testing activity or maintenance for greater inherent reliability and reduced risk potential. This thesis underscores the application of the FMECA technique to critique associated risk of the Subsea BOP system. System Functional diagrams was developed with boundaries defined, a FMECA were carried out and an initial select list of critical component failure modes identified. The limitations surrounding the confidence of the FMECA failure modes ranking outcome based on Risk priority number (RPN) is presented and potential variations in risk interpretation are discussed. The main contribution in this thesis is an innovative framework utilising Multicriteria decision making (MCDA) analysis techniques with consideration of fuzzy interval data is applied to the Subsea BOP system critical failure modes from the FMECA analysis. It utilised nine criticality assessment criteria deduced from expert consultation to obtain a more reliable ranking of failure modes. The MCDA techniques applied includes the technique for order of Preference for similarity to the Ideal Solution (TOPSIS), Fuzzy TOPSIS, TOPSIS with interval data, and Preference Ranking Organization Method for Enrichment of Evaluations (PROMETHEE). The outcome of the Multi-criteria analysis of the BOP system clearly shows failures of the Wellhead connector, LMRP hydraulic connector and Control system related failure as the Top 3 most critical failure with respect to a well control. The critical failure mode and components outcome from the analysis in this thesis is validated using failure data from industry database and a sensitivity analysis carried out. The importance of maintenance, testing and redundancy to the BOP system criticality was established by the sensitivity analysis. The potential for MCDA to be used for more specific analysis of criteria for a technology was demonstrated. Improper maintenance, inspection, testing (functional and pressure) are critical to the BOP system performance and sustenance of a high reliability level. Material selection and performance of components (seals, flanges, packers, bolts, mechanical body housings) relative to use environment and operational conditions is fundamental to avoiding failure mechanisms occurrence. Also worthy of notice is the contribution of personnel and organisations (by way of procedures to robustness and verification structure to ensure standard expected practices/rules are followed) to failures as seen in the root cause discussion. OEMs, operators and drilling contractors to periodically review operation scenarios relative to BOP system product design through the use of a Failure reporting analysis and corrective action system. This can improve design of monitoring systems, informs requirement for re-qualification of technology and/or next generation designs. Operations personnel are to correctly log in failures in these systems, and responsible Authority to ensure root cause analysis is done to uncover underlying issue initiating and driving failures

Instrumentation, Electrical Drive Specification and Software Concept for an Electro-Hydrostatic Subsea Valve Actuator

TCC(graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia de Controle e Automação.A Bosch Rexroth AG é uma companhia de engenharia especializada em acionamento e controle de todo porte, para aplicações industriais e móveis. Atualmente ela é a unidade de Negócios de Tecnologia da Automação da Robert Bosch GmbH, sendo uma subsidiária integral da última. Dentre os setores industriais da companhia, o setor Marine & Offshore desenvolve soluções de atuação e controle nos processos de exploração e produção de petróleo e gás offshore, também na instalação, comissionamento e decomissionamento de plataformas e turbinas eólicas offshore. Recentemente, com mais descobertas de campos petrolíferos em águas profundas (> 1000 m de profundidade), novas tecnologias buscam reduzir os custos da extração e maximizar a produção. Para isso, uma tendência no setor está propendendo em transferir a infraestrutura das plataformas na superfície para o fundo do mar. No entanto, as elevadas pressões, grandes distâncias de transmissão de energia/informação e o ambiente quimicamente agressivo da zona batipelágica, são alguns dos grandes desafios no desenvolvimento da tecnologia para este setor. Neste trabalho será proposto um novo conceito de um atuador compacto eletro-hidrostático para válvulas em árvores de Natal molhadas, manifold e chokes. Primeiramente será dado uma perspectiva geral da exploração de petroléo offshore e será ilustrado o estado da arte dos atuadores no mercado, e as vantagens do projeto proposto sobre as tecnologias atuais. Finalmente, serão explicadas as metodologias de projeto utilizadas no decorrer do trabalho. No capítulo seguinte serão esclarecidos todos os requisitos de projeto, os quais foram definidos à partir de uma descrição da aplicação, amparado em normas internacionais de engenharia, padrões internos da Bosch Rexroth, e acordos entre os parceiros de desenvolvimento de projeto. O terceiro capítulo cobrirá a etapa de especificação e seleção dos atuadores, transdutores e demais elementos eletro-eletrônicos que compõem todas as partes do sistema, bem como a elaboração dos mecanismos do sistema elétrico. Nesta seção também serão descritos os sistemas de acionamento elétrico e monitoramento do sistema. O início do desenvolvimento conceitual do software para o controle e interface do sistema será descrito no capítulo quatro. Nele serão descritos através de diagramas formais a arquitetura básica, o funcionamento do software, a abstração do sistema, e a funções necessárias para cumprir os requisitos de projeto. Os resultados da avaliação do cumprimento dos requisitos através das soluções propostas serão discutidos no quinto capítulo. Por fim, este documento se concluirá com uma breve explanação dos trabalhos futuros para a finalização do projeto como um todo.Bosch Rexroth AG is an engineering company specialized in drive and control technologies, including for the Marine & Offshore industry. Recently, with the growing discovery of oil and gas fields in deep waters (> 1000 meters depth), new technologies seek to reduce the extraction costs and maximize production. To achieve these goals, a trend in the sector is transferring the surface infrastructure to the seabed. However, the high pressure, long distances of energy and material transport and the chemically harsh environment of the bathypelagic zone are great challenges to overcome while developing technologies for this sector. In this thesis, it is exhibited a proposition of a novel concept of compact electro-hydrostatic valve actuators for subsea Christmas trees, manifolds and chokes. It’s illustrated the state of art in valve actuators available in the market and the advantages of the proposed project over the current technologies. This work focuses primarily in the synthesis of the electrical drive system design, the system instrumentation and the control software concep

Deepwater Gulf of Mexico Oil Spill Scenarios Development and Their Associated Risk Assessment

World’s growing energy demand has pushed oil companies to explore and produce hydrocarbons in complex and technologically challenging deepwater environments. These difficult and complex operations involve the risk of major accidents as well, demonstrated by disasters such as the explosion and fire on the UK production platform Piper Alpha and capsizing of the Deepwater Horizon rig in the Gulf of Mexico (GoM). Accidents cause death, suffering, pollution of the environment, disruption of business and bad reputation to oil industry. A quantitative risk analysis technique has been used in this study to identify and categorize risk associated with different life phases of a deepwater well. Volume of oil released to the environment is used as a risk indicator. Five oil spill scenarios related to drilling and production life phases of a deepwater well are modeled. Risks associated with drilling an exploratory well in the deepwaters of GoM are analyzed in Scenario-1. A representative well location and corresponding reservoir properties were used to estimate the worst case discharge rates (WCD). Fault tree analysis (FTA) was performed to identify and categorize different hazards. Unexpected pore pressure and delayed response to an emergency situation were identified as two most important parameters contributing to overall risk of the system. In Scenario-2 an underground blowout was modeled by using representative geological settings from Popeye-Genesis field. A shallower low pressure zone is exposed to a deeper high pressure zone during drilling. The time to recharge the shallower zone to its fracture pressure is estimated. The shallower zone will transmit hydrocarbons to sea floor once its fracture pressure is reached. Risks associated with production life phase of a deepwater well are modeled in scenario-3. A representative well location and corresponding reservoir properties were used to estimate the WCD. FTA showed that sand screen and subsea tree control failures were main elements contributing to risk. In scenario-4 risk associated with floating production and offloading (FPSO) system for GoM are quantitatively and qualitatively presented. Scenario-5 deals with oil spill risk associated with severe weather conditions. An example mudslide calculation for SP-70 block of GoM is presented

Application of SIMULINK to Emulate Subsea Production System (SPS) Control Functions

Subsea control systems in subsea production system (SPS) play a vital role in the safe and productive operation of any oil or gas field. These systems operate in extreme environments, thus making the installation and commissioning the system risky and costly. For a new developer, a better understanding on how the system works is needed to ensure that the system will meet all design specifications and reduce the risk and costs associated with installation and commissioning. Hence, leading oil and gas companies are turning to simulation software where the whole subsea control systems from the Hydraulic Power Unit to the Subsea Control Module can be modeled. This project aims to develop a SIMULINK model for a specific SPS and to assist in ensuring that the system will function accordingly. The scope of the project is to concentrate on the movement of the gate valve in subsea control system where the flow of an oil and gas is controlled. The methodology of the project involves collection of technical details and data regarding subsea control modules, identify elements of the control system, arrangement block diagram notation of the SIMULINK software, the acquisition of the SPS design parameters, and the development of SPS control system equation. Simulation result shows that the gate valve is fully open at 10cm within 0.075s. This will be useful to conduct a sensitivity analysis in the matter of SPS changing key design parameters. Moreover, this project will give lots of advantages to a new developer to understand the system well before developing the actual SPS control system

Techno-economic-environmental optimisation of natural gas supply chain GHG emissions mitigation

While the natural gas (NG) suppliers are under unprecedented pressure to reduce their Greenhouse Gas (GHG) footprint, various emissions reduction technologies have become available. Comparing their GHG mitigation performance and cost effectiveness has thus become increasingly relevant. This research developed a novel and accurate set of tools for GHG emissions estimation and for the cost assessment of emissions mitigation options for NG chains. These were combined in a first time proposed techno-economic and environmental optimisation framework to identify effective and cost efficient GHG emissions reduction options for NG operations in a regional context. The Life Cycle Assessment (LCA) methodology was used to develop inventory models for: offshore production and pre-processing, onshore processing and liquefaction, offshore pipeline transport and offshore Liquefied Natural Gas (LNG) transport. The modular life cycle inventory models developed provide significant advances compared to previously developed models: (i) they capture the impact of different operational practices, technologies and climatic conditions on the emissions, (ii) emission estimations are made for the whole life of facilities, historically and with future projections, using a combination of material balance and engineering calculations; these are configured to the specifics of facilities analysed increasing substantially estimation accuracy, (iii) they enable the assessment of uncertainty for emission estimations. The models were validated using industry data for five NG chains with operations in Norway (2), UK, Australia and Bolivia. A methodology to compare the cost effectiveness of different emissions reduction technologies through Marginal Abatement Cost Curves was also developed for a large range of CO2 and CH4 emissions mitigation options. The cost models developed account for capital and operational expenditure, as well as effects on revenues and tax liabilities. The approach was validated using three of the NG operations studied, located in Norway (2) and Australia. Finally, a mixed-integer multi-objective optimisation model was developed to identify regional opportunities for GHG emissions reduction and cost minimisation in offshore upstream NG value chains through (i) joint power generation and (ii) connection with offshore wind farms. This model was tested for a set of 12 offshore platforms located in the UK Southern North Sea obtaining a 25% reduction of the network’s cumulative CO2 emissions over a ten year future period. This research has proven for the first time that there can be significant difference in GHG performance between neighbouring NG facilities, or within the same facility in consecutive years, found to be up to 54 and 44%, respectively. Moreover, it has shown that the embodied GHG footprint of NG product delivered at different markets will vary significantly even when it is originating from a single source. Thus, generic or regional averages, often employed by LCA practitioners, are not reliable for the industry’s own reporting and for regulatory purposes. In this context, policy makers should consider that imported NG may arrive with embodied GHG footprints varying by more than 50%. Moreover, to effectively identify which NG value chains or regions offer comparatively lower GHG footprints, it is necessary to perform value chain specific LCA studies, using real operational data at a unit process granularity. Regarding emissions reduction options and cost considerations, while integration with renewables and efficiency improvements could perform well for conventional offshore operations, in unconventional onshore operations, targeting well completions, casing and tank vents were shown to have a higher GHG reduction potential. The offshore Norwegian, onshore Norwegian and onshore Australian industry facilities studied were found to have added individual mitigation potential of 2,522, 346 and 13,947 ktonnes CO2 equivalent over investment horizons of 5, 15 and 10 years respectively. All the sites studied were also found to have abatement options with negative implementation costs. The industry and policy makers should, thus, consider that abatement potentials and costs vary significantly by facility depending on its characteristics and context.The implementation of the novel life cycle assessment and cost assessment tools developed in this research and the multi-objective techno-economic and emissions reduction optimisation framework enable for the first time GHG reporting of substantially increased accuracy and unique evidence in support of the efforts industry aims to employ to reduce their effects on the climate.Open Acces

New risk categorization system for well integrity - wells in operation

Master's thesis in Industrial economicsWell integrity is defined as:” the application of technical, operational and organizational solutions to reduce risk of uncontrolled release of formation fluids, throughout the life cycle of a well” (1). An uncontrolled release of hydrocarbons to the surroundings may have devastating consequences involving loss of lives, environmental damage and huge economic impact. Therefore it is extremely important that the integrity is assured at all times. A two barrier criterion is required for all the wells on the Norwegian Continental Shelf in contact with an over pressured reservoir. The dual barrier envelopes shall reduce the risk of a hydrocarbon leak to the surroundings. The highest risk for a major accident is experienced and considered to be during drilling and well operations, and not in the production / injection phase. However, history clearly shows the risk for a blowout / well release from wells that have been in production with the Bravo and Snorre A blowouts as serious examples. With today’s extended well lifetime, the integrity in the operational phase needs increased focus as the failure rate in old wells may become more frequent. To have overview and control of the wells in operation a categorization system for well integrity was developed in Norwegian Oil and Gas Recommended Guidelines 117, chapter 4. This system is based on the condition and number of barriers in a well, thus it is in direct association with the probability of a leak to the surroundings. Operators on the Norwegian Continental Shelf have used this system as a basis when developing their own risk status codes, but there is a common interest for a categorization system that captures the total risk picture in a better way. By only looking into the physical barrier status of the wells, an important part of the overall risk is left out. The leak is not quantified (above the acceptance criteria), if it is serious or insignificant, and the potential consequences of the leak are not taken into consideration. Statoil is one of the operators realizing the need for a risk status code that includes these aspects. They have experienced difficulties when ranking and prioritizing wells outside the dual barrier criterion, and are interested in a system for further differentiation of the most critical wells. In this way the most risky wells can be prioritized first and evaluated in a more detailed risk assessment. The main scope of this thesis is suggesting a categorization system describing the overall risk in a better way than the existing. This is done by implementing the potential consequences as a second dimension in addition to the barrier status. Risk can be defined as the combination of the probability of an event and the associated consequences, and a status including both these elements will give a better description of the overall risk. As the main task is producing a new classification system for the consequences, this will be the part emphasized in the suggested models. In combination with the existing barrier status codes (based on the color codes in Norwegian Oil and Gas Recommended Guidelines 117 for Well Integrity) this gives a status which represents a more complete risk picture. This thesis suggests several systems for consequence categorization, and the one most representative is presented as model 3. By testing it on 5 field cases, the results clearly show why the new system gives a better description of the overall risk contra the existing.