OIL AND GAS. engineering analysis asset integrity technical safety environmental

Transcription

1 OIL AND GAS engineering analysis asset integrity technical safety environmental

2 FRAZER-NASH CONSULTANCY We develop requirements for projects, assess new concepts, analyse performance, assure safety, and plan through-life support. Formed in 1971 and now part of the 2.9bn Babcock International Group, we provide our expertise to operators of production and power generation facilities worldwide. Our customers range from the largest producers to small specialist providers; our services span the needs of both new developments and legacy assets. Our 500 staff are experts in asset management, asset integrity, flow assurance, and safety. Worldwide offices include presences in Aberdeen, south-west London, and Australia.

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5 PEOPLE We now employ over 500 people in locations worldwide. Below are some of the key individuals who head up our Oil and Gas Business. Dr Simon Rees Many years experience of oil and gas starting at the age of eighteen, when he worked as a helicopter loadmaster on an exploration rig in the Ecuadorian Oriente. He subsequently specialised in mathematical modelling, especially fluid dynamics, and now looks after the company's growing portfolio of onshore and offshore activities. Sarah Marshall Sarah manages the Aberdeen end of our Oil and Gas business from our office in Westhill. With a technical background of over ten years in detailed design, analysis, and installation of offshore equipment, including spells working in the challenging environment in offshore Angola, she brings enthusiasm and practical experience to the team. Dr Roger Dennis A recognised world expert in the analysis of HTHP systems, Roger manages four groups of structural analysis experts. Group specialisms include fatigue, fracture, material modelling, residual stress predictions, dynamics, impact, and independent technical assessment. Justin Jones Justin has extensive experience in the application of engineering analysis to complex non-linear and dynamic problems both as the technical lead and project manager. He also has a broad knowledge of Finite Element Analysis, structural analysis and design of offshore platforms. John Devlin Professional electrical engineer with 26 years experience of the management of people and the delivery of projects in a wide variety of industries, including Oil & Gas, Marine and Power. Has substantial experience in design, installation, testing and commissioning of a wide range of HV and LV plant, as well as the operation and maintenance of plant and systems. Ian Bottomley The leader of our Dorking-based integrity group, Ian is equally at home solving problems in process equipment, mechanical plant, offshore structures, and floating assets. An expert in fracture mechanics, Ian is familiar with the latest research across the offshore and nuclear industries, and his team provide fatigue, fitness-for-service, and life-extension analyses to operators worldwide. Dr Graham Hawkes After a successful period as a lecturer and researcher in fluid mechanics at Oxford University, Graham joined Frazer-Nash where his knowledge of complex pipe flows has proven invaluable. Now the leader of our flow assurance and process modelling capability, Graham's team specialises in solving difficult multiphase flow and heat transfer problems. Dr Richard Scott Renowned for his problem-solving abilities in fluid dynamics, thermodynamics and acoustics.richard's exacting standards are the principle basis for our reputation forexcellence. Deploying his 15 years of experience directly in supportof some of our more difficult projects, where his ability to quickly identifythe core of any problem has helped many customers find a solution.

6 SERVICES We provide an immense breadth of analysis and design services to the oil and gas industry, allowing us to take on complex packages of related tasks, or deep studies into specific problems. Our clients value our ability to understand their requirements rapidly, and provide a service that is timely, accurate, and efficient. Fluids Services ATEX assessment of ventilation & gas detection systems Blast modelling Chemical Injection modelling Cool down modelling Dispersion (smoke, gas & plume) modelling Dynamic flow network analysis Erosion modelling Fire modelling Flow induced vibration (FIV) Heat transfer between fluids & structures Helicopter operations HVAC modelling Joule-Thomson cooling Multiphase flow modelling (slugging) Multiphase fluid modelling (sloshing) Vortex induced vibration (VIV) Wave loading (non-linear, e.g. wave in deck) Mechanical Integrity Services Code assessment ECA - component based ECA - pipeline fracture Explicit large strain Failure cause analysis Fatigue (SN) Fitness for service Jacket modelling (pushover) Non-standard materials modelling Pipeline analysis Pipework analysis Pressure vessels Repair design & substantiation Static structures Stress analysis and design Structural collapse / plastic collapse Structural reliability analysis (SRA) Structural strengthening (wraps, clamps, cementing) Subsea Equipment Topsides Equipment Rotating Equipment Pipelines & Risers Platforms FPSOs

7 Welding analysis Structural Dynamics Services Blast response Dropped objects Rotor dynamics Ship impact, shock loadings Vibration Safety, Risk & Reliability ATEX, DSEAR, and COMAH Noise & vibration assessment Environmental management systems FMEA/FMECA/FTA CAP437 Control system safety Reliability & reliability based inspection Risk management Safety case development Electrical Control and Instrumentation (EC&I) ATEX / DSEAR Equipment DC systems and batteries Distribution automation and management Earthing and lightning protection Electrical protection Energy management Fire protection HV+LV motors and generators HV+LV switchgear Power and distribution transformers Process control Programmable controllers SCADA and telemetry C&I Integrity Naval Architecture and structures Corrosion Cathodic protection system design & analysis Ship motions Fatigue and fracture analyisis Green seas loading Tank sloshing Ship-Ship transfer modelling

8 Frazer-Nash in the Oil & Gas Industry We've been working in the Oil & Gas sector for many years. Our skills are best illustrated by the case study Project Management Safety & Reliability Topsides Mechanical Topsides Process Project management and third party technical verification (fitness for purpose) of replacement gas turbine exhausts Gulf of Mexico Stress Concentration Regions (SCRs) and Engineering Critical Assessment (ECA) of flowlines and risers Gulf of Mexico Insulation system design and cool down performance analysis of an In-Line Sled (ILS) Gulf of Mexico ATEX compliance assessment of a gas turbine enclosure ventilation and gas detection system Vortex Induced Vibration (VIV) assessment of a flare boom SWIS JIP - Thermal modelling of infield joint coating failures Thermo-fluid process modelling of well flowline changes for EOR FMECA for operation of 120T & 50T winches on a jacket structure Fitness for service assessment of a water injection header Fitness for service assessment of tube shell heat exchangers Global Design support for a subsea cutting tool nozzle Joule-Thomson modelling and fitness for service assessment of a blowdown valve Gulf of Mexico Erosion modelling of an orifice plate for a gas lift injection system Western Australia Blast design and FEA of a cabin workshop Gulf of Mexico CFD investigation of design modifications to an orifice plate for a gas lift injection system Failure cause analysis of small bore branch pipe on gas compression train Gulf of Mexico Cool down performance analysis of a Pipeline End Manifold (PLEM) Vibration and pipework stress analysis of a topsides flowline Angola Dynamic pressure analysis of tube ruptures in a tube shell heat exchanger Pipework stress analysis of a subsea flowline and riser Gulf of Mexico Flow Induced Vibration (FIV) screening audit of a subsea flowline network Fitness for purpose assessment of a tube shell heat exchanger Gulf of Mexico Cool down performance analysis of a Pipeline End Manifold (PLEM) Insulation design and thermal CFD analysis of a wellhead Gulf of Mexico Flow Induced Vibration (FIV) screening audit of a subsea flowline network ATEX compliance assessment of a gas turbine enclosure ventilation and gas detection system Gulf of Mexico Flow Induced Vibration (FIV) screening against measured system parameters Failure cause analysis and fitness for service assessment of a gas turbine exhaust duct CFD thermal and cool down analysis of a subsea tree Fitness for service assessment (FEA collapse analysis) of a water injection header Brazil Performance analysis of a separator internals using multiphase CFD Hydrodynamic analysis of an umbilical installation process Nigeria Thermal and cool down performance analysis of subsea equipment Angola Fitness for service assessment (FEA collapse analysis) of a water injection header Angola Repair bracing analysis for a gas lift riser Failure cause analysis and fitness for service assessment of a gas turbine exhaust duct Ship impact assessment for a jacket structure Design support for pipeline coating device FMECA for operation of a legacy winch Re-rating of tube shell heat exchangers Pipework stress analysis of a flowline Gulf of Mexico Reliability analysis of a flowline jumper Hydrodynamic towhead simulations Gulf of Mexico Flow Induced Vibration (FIV) data collation Joule-Thomson analysis of a choke valve Failure cause analysis of a separator nozzle

9 examples given later, but a small list of some recent projects is given below: Design Metocean Flow Assurance Subsea Integrity Gulf of Mexico Gulf of Mexico Gulf of Mexico Gulf of Mexico Nigeria Gulf of Mexico Gulf of Mexico Alaska Caspian Sea Irish Sea Gulf of Mexico Middle East Nigeria Nigeria Nigeria R&D Nigeria Caspian Sea Sakhalin Sakhalin Alaska Angola Global Global R&D Angola Cool down performance and hydrate inhibitor analysis of a Pipeline End Manifold (PLEM) and jumper assembly Flow Induced Vibration (FIV) forcing prediction (CFD analysis) of a T-piece to calculate FIV forcing ATEX compliance assessment of a gas turbine enclosure ventilation and gas detection system Design investigation for a ventilation and gas detection system for a gas turbine enclosure Engineering Critical Assessment (ECA) of subsea flowlines ATEX compliance assessment of a gas turbine enclosure ventilation and gas detection system Failure cause analysis for a gas turbine WHRU tube bank Engineering Critical Assessment (ECA) of flowline jumpers with misaligned welds Performance analysis of a separator using multiphase CFD Composite repair design and substantiation for a heli-deck support structure Failure cause analysis of an NGL transfer pump Dynamic pressure analysis to verify the effectiveness of a HIPPS valve system Assessment of object impacts on a subsea manifold Design and performance analysis of a separator internals using multiphase CFD Engineering Critical Assessment (ECA) of subsea flowlines Failure cause analysis and fitness for service assessment of a CGF reboiler Failure cause analysis of a heating tube coupling Failure cause analysis and fitness for service assessment of a gas turbine exhaust Dropped object impact assessment for lifting operations Design and performance analysis of a separator internals using multiphase CFD Engineering Critical Assessment (ECA) of reeled flowlines Joule-Thomson cooling analysis of an orifice plate for a gas lift injection system Composite repair design and substantiation for a 30" export header Vibration induced fatigue assessment of a flare stack process pipework Project management of a test programme for validating cool down simulation methods Thermal and cool down performance analysis of subsea equipment Design analysis of the ventilation system for a gas turbine enclosure Analysis of the effect of conductor casing run-in operations of fatigue life of components Thermal CFD analysis of a test rig for cool down method validation tests Insulation design and thermal CFD analysis of a subsea tree Atmospheric modelling of hydrocarbon gas leak dispersion around a rig Thermal CFD and cool down analysis of a multiphase flow meter Performance analysis of a vertical separator using multiphase CFD Thermal CFD and cool down analysis of a subsea manifold Failure cause analysis and fitness for service assessment of a crude oil heat exchanger Failure cause analysis of a high pressure flare line Failure cause analysis of a gas lift riser Fitness for service assessment of a coalescer Review of the internal FMEA practices Design support for pipeline renovation device FMEA for the launch of a new vessel Development of cool down analysis methods Hydrodynamic simulations of a towhead Pressure vessel code assessment Fitness for service assessment of a gas lift riser

10 Providing services to operators, engineering companies and equipment suppliers across the world

11 CASE STUDY FPSO - ASSURANCE AND INTEGRITY THROUGH STRENGTH ASSESSMENT THE CHALLENGE Floating Production, Storage and Offloading (FPSO) systems are valuable and complex assets. To assure our client of the integrity of one such vessel and its ability to withstand its operating conditions, we were asked to perform strength and fatigue assessments. OUR SOLUTION We built a global model of the ship structure, turret and the module frame structure using SESAM (DNV software). Using over 600 different combinations of wave height, frequency and direction to give a complete picture of the vessel's response, we performed three assessments: External FPSO hull strength analysis Strength assessment of the ship structure under the impact of extreme waves Spectral fatigue assessment to account for cumulative damage of through life offshore operation, including seasonal changes in wave loading Strength assessment of the mooring system for an extreme 10,000 year wave THE RESULT By comparing the predicted stresses on the FPSO hull and internal structures with the classification society rules, we concluded that the vessel was sufficiently strong. Internal Modular structural assessment After assessing the potential fatigue damage that the FPSO would accumulate we calculated its fatigue life using a statistical model of wave loading. Finally, we developed a non-linear model of the mooring system that included the mooring lines, risers and buoyancy. After these additional refinements we applied the extreme loading conditions, and assessed the integrity of the mooring chains. THE BENEFITS Frazer-Nash were able to provide assurance to our client that their asset would survive its projected operational life. We not only satisfied their current design needs but were able to save them significant cost by anticipating future requirements that could affect the overall strength of the FPSO.

12 CASE STUDY PROLONGING THE DESIGN LIFE OF A GAS TURBINE EXHAUST THE CHALLENGE Offshore gas turbine exhaust systems must support heat recovery and also be light enough to be easily installed or removed, whilst remaining unaffected by cyclic thermal loads and dynamic pressure fluctuations. Failures are common due to the extremes of gas temperature and velocity that occur. Gas turbine downtime can be extremely costly and remedial measures can involve long lead times and may not address the root cause of past failures. The gas turbine exhaust systems on the Bruce platform have suffered repeated failures during their operating lifetime. BP came to Frazer-Nash to see whether we could determine the shortcomings of the existing design. We then suggested and evaluated design solutions to prevent future failures. OUR SOLUTION We diagnosed the cause of the problems in a three stage process: A Computational Fluid Dynamics (CFD) model incorporating advanced turbulence modelling techniques to capture in detail the pressure fluctuations inside the exhaust system These fluctuations were applied to a structural model of the system to determine local stresses and pinpoint regions of likely failure. A thermal model of the system then determined the stresses generated by thermal cycling during start-up and shut down New design concepts were developed and assessed based on the results of the analyses. This included additional analyses to cover installation and lifting loads THE BENEFITS We undertook detailed analysis of the failure mechanisms of the existing exhaust systems; provided concept designs for improved replacements; supported the engineering, procurement and construction; undertook overall project management and assessed the suitability of the installation and lifting systems. Images of CDFD modelling of a GT exhaust duct showing varying pressure of the gas on the duct walls and velocities on moving particles within the duct As a result, BP can have greater confidence that the new design will improve the overall reliability of the system. WHY CHOOSE FRAZER-NASH? During the last 20 years we have worked with a range of clients providing design and analysis for auxiliary gas turbines. This includes Gas Turbine OEMs, package manufacturers and operators. Our extensive knowledge in multiple disciplines enables us to resolve all aspects of a problem including fluid dynamics, manufacturing and installation, and structural design and optimisation.

13 CASE STUDY BLAST RESISTANT DESIGN THE CHALLENGE Control buildings and other critical structures on oil refinery sites must be blast resistant to ensure that people and critical equipment are protected. Our client builds the fully fitted out blast resistant modules, including control buildings and substations, in parts to be shipped to site. There are often requirements for large open spans, which means that the roof structure and connections are particularly critical. Our skills and experience mean we can design a building which meets all the strength requirements but is as light as possible and easy to construct, enabling our client to win projects in a competitive market place. OUR INVOLVEMENT Initially we carried out scoping calculations on the building which enabled our client to enter a competitive bid and win the work. We were then awarded the contract to carry out the outline design and supporting blast and code assessments for the building. Using the structural form we proposed at the bid stage, a finite element model was produced and analysed under the blast loading defined by the operator. A full dynamic analysis was carried out with each wall facing the blast, which showed that the building was efficiently designed, with some plasticity but deflections within allowable levels. The finite element model was also used for the transportation analysis, since lifting the half sections of building places large loads on the structure. Since the building was to be manufactured in the UK and shipped to Australia, an assessment of the fatigue damage from transportation and shipping loads was carried out. The building had to meet Australian structural steelwork codes, so a set of calculations were prepared demonstrating compliance under the required environmental loads, including the extremely high wind speeds for North Western Australia. EXTRA ADDED VALUE By building good relationships with our client and keeping them informed of the direction of the design, we ensured that when it came to construction, there were no hold ups. This enabled the client to produce the building on schedule for shipment to Australia. Our blast design skills have be applied to numerous applications such as concrete structures, offshore steel structures and pressure vessels for both internal and external blast.

14 CASE STUDY SUBSEA CATHODIC PROTECTION SYSTEM REQUIREMENTS THE CHALLENGE Offshore structures present unique corrosion challenges that require innovative Cathodic Protection (CP) systems. Retrofitting systems to old platforms requires an understanding of both the existing structure and CP systems, plus the requirements of the new systems and the interactions between each. By understanding the complexities of the local subsea environment, intricacies of corrosion mechanisms and practicalities of working offshore, we can determine the protection provided by the existing systems and develop and predict the performance of retrofit solutions. This helps the operator to plan and efficiently maintain their CP systems, aiding continued and safe production. OUR SOLUTION Using computer simulation our engineers design, assess and optimise Cathodic Protection (CP) systems, such as sacrificial anodes and Impressed Current Cathodic Protection (ICCP) and hybrid systems using the following techniques: Performance assessments of installed cathodic protection systems Identification of Hot Spots that potentially accelerate corrosion Calculate corrosion rates in affected zones Prediction of the protection levels on subsea jacket structure and from an ICCP system Review of system operation; over or under protection? Assessment of human factors on operating procedures and practices of cathodic protection systems Cost-benefit assessments of various cathodic protection solutions based on complexity of installation as well as raw materials THE BENEFITS We can predict the locations most susceptible to galvanic corrosion and model the protection provided by various types and configurations of CP systems. This enables us to rapidly design and assess the optimum CP solutions for offshore assets. By providing an optimised cathodic protection system configuration we can provide measurable technical and commercial benefits to designers, manufacturers and operators of vessels and offshore structures.

15 CASE STUDY SAND EROSION - UNDERSTANDING THE RISKS THE CHALLENGE Subsea oil and gas flowlines operate in extreme conditions, with exposure to high thermal and mechanical loads whilst transporting complex multiphase fluids. The majority of these challenges are concerned with optimising production, minimising structural loads and mitigating the risk of blockages forming during flowline shutdowns. However, production streams often contain significant sand content; therefore, flowline erosion is a real concern. The consequences of sand erosion are irreversible and given the risks of impact on production and safety it is important to understand the erosion characteristics. Often erosion risk can be managed by operators' rules of thumb developed through years of experience. However, when unusual production conditions or flowline geometries are encountered, further information is required to quantify the erosion risk. Erosion assessments can be performed experimentally but this is a complex process with long lead times, high costs and difficulty in replicating realistic production conditions. What was required was a means of quantifying erosion rates and risk for a variety of flowline components within short timescales without resorting to testing. CFD modelling of impact velocities off moving particles within th e pipe bend OUR SOLUTION Using our significant experience of Computational Fluid Dynamics (CFD) to model complex multiphase flows we were able to develop and run set of numerical experiments to simulate the mechanics of flowline erosion. This comprised: Computing the underlying fluid flow behaviour within the flowline component at realistic production conditions Numerically injecting thousands of individual sand particles into the flowline and tracking their movement within the fluid stream and their interactions with internal walls in terms of impact velocities and collision angles We then collected all the data for the particle impacts and used this as input to established erosion rate models which are tailored to specific materials. Using this approach we were able to generate detailed and statistically robust erosion patterns on the internal walls and quantify peak erosion rates. This information enabled us to rapidly explore the sensitivity of erosion hotspots to component geometry and production conditions and identify how component life could be increased.

16 Our breadth of knowledge in oil and gas and other industries allows us to deliver innovative insight and solutions to the industry s toughest challenges.

17 CASE STUDY ENGINEERING CRITICAL ASSESSMENT (ECA) THE CHALLENGE Our client procured a section of lined pipe to be installed from a reel lay vessel. The ECA which had been carried out at the design phase had assumed three strain cycles during the reeling event, and the flaw acceptance criteria at manufacture had been specified on that basis. However, during installation the number of strain cycles was significantly greater. Our client required assurance that defects at the limits of the flaw acceptance criteria would not grow to a critical size by end of life, under the revised installation procedure. OUR SOLUTION Reviewing the results of the previous ECA it was apparent that additional ductile tearing could be caused by the extra strain cycles during reeling. This could lead to end of life defects larger than the calculated critical defect size. Our experts used their experience of API579, BS7910 and R6 to re-evaluate five elements of the ECA: The stress intensity factor and reference stress solutions and how appropriate they were The use of revised vortex induced vibration fatigue cycles during installation Any adjustments to the fatigue crack growth curves to represent the operational phase The bending stress calculations associated with joint misalignment for the actual adjacent pipe geometries Revised analysis-based residual stress assumptions for the pipe at end-of-life Based on these refinements a more detailed and accurate, and less conservative, assessment was then possible. THE BENEFITS The calculations were re-worked to determine revised defect growth estimates during reeling and fatigue crack growth predictions during installation and service. The critical defect size calculations were also revised and larger limiting sizes calculated. Using our extensive fracture mechanics expertise we were able to significantly reduce the conservatism in the ECA carried out at the design stage. This allowed the additional growth caused by the increased number of reeling strain cycles to be accommodated without changing the original flaw acceptance criteria.

18 We provide an immense breadth of analysis and design services to the oil and gas industry, allowing us to take on complex packages of related tasks, or deep studies into specific problems.

19 CASE STUDY FITNESS FOR SERVICE ASSESSMENT THE CHALLENGE During routine maintenance, damage was found to have occurred to the inner bore surface of a branch connection in a Water Injection Header. Our client identified between 20 and 30 similar connections on the same header which could have suffered similar damage. This was an unexpected problem and only a very short period of time was available to inspect the branches and substantiate their integrity before production would be affected. The branch connections were quickly identified to be a bespoke design and no detailed drawings were available. OUR SOLUTION We developed a simple, flexible and effective approach to quickly identify those branch connections that had suffered damage attributed to a combination of corrosion and erosion damage. Our structural analysis team identified the key dimensions and the necessary inspection grid for Non-Destructive Testing (NDT) thickness measurement. The offshore inspection team then used this to gather the data from the branches most at risk. We developed an initial screening assessment against which the damaged branches could be assessed, which involved: API579 level 2 assessments, using a simple area replacement approach to better understand the extent of the damage on each branch Identification of key dimensions needing inspection When the results of the analysis produced low reserve factors a more detailed finite element model was built in accordance with a level 3 assessment to demonstrate protection against plastic collapse The wall thickness of these detailed models was then reduced until the limits of the solution for the applied loads were reached The mesh of the finite element model was built to match the inspection grid so that individual elements could be removed easily and the associated damage on each branch assessed When branch connections were in close proximity to major structural discontinuities, we adapted the model to consider these scenarios Analysis model to simulate actual corrosion/erosion damage redution in wall thickness THE BENEFITS The initial assessments and finite element model were developed in a few days allowing the analysis to drive the inspections. These models were developed so that individual branch connections and their associated damage could be assessed without the time-consuming process of re-building separate models. By quickly mobilising the right team with many years of experience, we demonstrated the fitness for service of all the damaged connections before the completion of the outage resulting in no further loss to production.

20 CASE STUDY ATEX COMPLIANCE FOR OFFSHORE POWER GENERATION THE CHALLENGE The considerable power demands of offshore production and processing platforms are usually met by the use of gas turbine power generators that provide reliable and cheap energy. However, these units are encased within acoustic enclosures which create the risk of explosion as the hot surfaces and natural gas combine. The design of these enclosures is governed by the pan-european DSEAR and ATEX Regulations which require assurances that the largest undetectable gas leak will not lead to an uncontained explosion. OUR SOLUTION Frazer-Nash worked under a joint industry project with the Health & Safety Executive to develop a process that would provide this assurance. Using Computational Fluid Dynamics (CFD), we analysed how the turbine and its enclosure were constructed. The CFD model highlighted areas where escaped gas could pool inside the acoustic enclosures, and then simulated the ventilating airflow throughout the enclosure. This identified a series of possible leak locations which could potentially lead to an explosion. The model also established whether a cloud of sufficient size could be created without tripping the gas detectors at the exit of the enclosure. Using this data, we then proposed a number of modifications to the enclosures, including: Using plating to control the ventilation flow and remove dead zones Modifying the ventilation flow volume Modifying the number, location, and setpoints of gas detectors The Health & Safety Executive was satisfied that once the acoustic enclosures had been amended, they would fully comply with the DSEAR and ATEX Regulations. THE BENEFITS Advanced CFD is just one of the tools Frazer-Nash utilise to calculate the probability and impacts of overpressure explosion. We also use FLACS (FLame ACceleration Simulator) which is an advanced tool for the modelling of ventilation, gas dispersion, vapour cloud explosions and blast in complex process areas.

21 CASE STUDY FMECA - CRANE WINCHES THE CHALLENGE ACE Winches are supplying two hydraulically powered, heavy capacity winches to a Danish oil and gas company as part of a repair scheme requiring various lifting arrangements at different stages of the programme. Due to the inherent risks associated with the particular platform, additional design integrity assurance was required in the form of a Failure Mode Effects Analysis and Criticality Analysis (FMECA). The identified failure modes needed to be assessed in terms of severity and probability, what mitigation is in place, and also if any further risk reduction activities were required. OUR INVOLVEMENT The purpose of this FMECA Study was to identify potential design weaknesses through a systematic analysis of the modes of failure, their causes and effects. The FMECA included analysis of failure mode criticality in terms of severity and probability, which enabled the failure modes to be ranked in terms of criticality (risk). To accomplish the analysis, we facilitated a series of review meetings at the client's site where both our knowledge of the FMECA process and ACE's Technical knowledge of the system allowed us to extract and record relevant information. This form of review process allowed the analysis to be performed effectively and within very short project timescales. EXTRA ADDED VALUE The analysis we undertook highlighted the areas of significant risk and enabled the client to focus design effort, where needed, and to present mitigating evidence to prove that the risks are being appropriately managed. As the FMECA was conducted at the design stage, potential problems were able to be resolved before manufacture, saving both time and money, as well as reducing operating risk.

22 CASE STUDY TANK SLOSHING THE CHALLENGE Our client designs and manufactures gas turbines for installation on the decks of floating oil production platforms. These turbines are fitted with their own oil supply tank for cooling and lubrication. The oil is collected in a sump before being scavenged back into the turbine. However, the motion of the ship allows the oil to slosh around inside the tank, and in some instances, the oil intakes and the heater element in the sump may be uncovered. This can cause air to be drawn into the oil system resulting in damage to the turbine. To mitigate this risk, Frazer-Nash was asked to analyse the existing design to determine the movement of the oil. The aim was to understand the limits of motion for which the unit will operate correctly and to ensure critical components were positioned to ensure maximum coverage. OUR INVOLVEMENT We established that the sloshing motion in the tank varied with conditions, and was affected by a number of factors, including: The amplitude and frequency of the pitching and rolling motion of the boat The height and displacement of the tank from the centre of rotation The geometric design of the tank and the position of internal obstructions The oil level in the tank To understand the interaction between all of these factors, we generated a computer simulation of the oil tank using three dimensional Computational Fluid Dynamics (CFD). We then simulated a range of motion to understand what was causing the components to be uncovered. Our evaluation showed that for the extreme motions modelled, the existing design was not able to maintain oil coverage on the critical components. This was reported to the client which allowed the component placement to be improved and tested before the unit was installed and run at sea.

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24 CASE STUDY FLOW INDUCED VIBRATION THE CHALLENGE Vibrations caused by the unsteady flow of production fluids are hard to predict (Flow Induced Vibration, or FIV), and can create unacceptable levels of fatigue. If FIV problems occur, then the situation must be rapidly examined to establish how production can be maintained at an acceptable level. In this project our client measured vibration levels that were neither predicted nor explained by conventional engineering studies. We were asked to make a more detailed study that would explain the phenomenon and hopefully provide a justification for continued high production rates. WHY CHOOSE FRAZER-NASH? Frazer-Nash's expertise in detailed fluid dynamics, fatigue analysis and subsea pipelines means that we are ideal for multi-discipline investigations of this type. The complexity of subsea systems required detailed analysis of specific features and components coupled with a parallel assessment of the global system dynamics. OUR APPROACH Our investigation followed three lines of study: Transient CFD modelling of flow within a mitred elbow. An analysis of the most credible sources, using a combination of scoping calculations and the measured data Detailed transient analysis using Large Eddy Simulation (LES), an advanced computational fluids technique that provides detailed, time-varying analysis of turbulent flows, and is considerably more accurate than conventional CFD methods Expert guidance for an onshore testing programme, including advice on scaling, set-up, instrumentation, and the analysis of results THE OUTCOME We discovered that a small set of components was responding to a previously unsuspected source of vibration. We were able to predict the flow rate bands at which the phenomena occurred, allowing production to return to an optimum level. Furthermore, the fundamental insight we gained has been incorporated into our client's design guidelines, ensuring that future facilities will avoid the problem.

25 CASE STUDY TECHNICAL MANAGEMENT OF OFFSHORE INSTRUMENTATION THE CHALLENGE During the operation of a large off-shore drilling and production platform in the, our client needed to measure a variety of interfaces and fluid levels. This would enable good process control of instrumentation deployed throughout the asset. Measurement is currently performed using nucleonic sensors which utilise gamma radiation sources and detectors to establish vessel fluid levels. Following 10 years of platform operation, a backlog of faults, repairs and non-functioning measurements had accumulated. A planned platform shutdown provided an opportunity to undertake a targeted campaign to bring sensors back online. OUR SOLUTION Challenging timescales defined by the platform shutdown schedule required a rapid deployment to the client's office in Aberdeen, where we: Gathered Information on the current issues Assessed vendor proposals and identified supporting material requirements Ensured all the documentation was in place to meet procurement deadlines Created a detailed schedule to match materials with resources Created work package documents and electrical drawings to detail the offshore tasks Monitored compliance with legislation for radioactive material Liaised between off-shore, on-shore, vendors and logistics representatives to deliver the planned improvements on schedule THE RESULT Using our flexibility and willingness to adopt our client's data management, purchasing and quality procedures we successfully managed the procurement, shipping and installation of over 400,000 worth of equipment in three months. From our vendor neutral position we acted as an interface between our client and the existing suppliers to assess proposed solutions, costs and risks. Using simple analysis and reporting tools we greatly reduced our client's cost. We provided a single point of knowledge for our client, providing clear insight and progress reports normally unachievable due to shift duration restrictions causing constant rotation of personnel. We allowed the client to keep overall control of the project in-house and retain knowledge of their own systems that would otherwise have been held by a third-party.

26 EQUAL TO YOUR CHALLENGE At Frazer-Nash we understand what s really important to our customers: a rapid response, high quality results combined with delivery on time.

27 For further details on our Oil & Gas services contact: Tel: or

28 Have you got a QR-Code reader on your mobile? Scan this code to go directly to our website. Frazer-Nash Consultancy Ltd Stonebridge House Dorking Business Park Dorking Surrey RH4 1HJ T +44 (0) F +44 (0) Other offices UNITED KINGDOM Aberdeen, Bristol, Burton-on-Trent, Dorchester, Glasgow, Gloucester, Plymouth & Warrington AUSTRALIA Adelaide & Melbourne