Http Fpso.olf.No 21625

OLF FPSO Project 2002

27/05/04 The Offshore Management Centre, RGU 1

A summary Report on

FPSO Lessons Learned, gatheredfrom 5 Norwegian FPSOs - May 2002

20 September 2002

Prepared for the Norwegian Oil Industry Association, OLF

The Offshore Management Centre,Robert Gordons University, Aberdeen



Preface

In 2001 OLF formed an Floating Production, Storage and Offloading (FPSO)Experience Transfer Workgroup. The group’s objectives are to facilitateexperience transfer between Norwegian FPSO operators and potentialoperators to reduce capital and operating costs and improve overalleffectiveness.

A decision was made in 2002 to interview Operating and Project staffinvolved in the 5 Norwegian FPSOs. The contractor RGU had been involved ina similar study in the UK and was therefore able to make comparisonsbetween UK and Norwegian experience. A team from RGU, OLF and Marintecconducted the interviews and prepared the interview summaries. The teamconsisted of;

Mark Capsey (RGU)David Llewelyn (OLF)Erik Dyrkoren (Marintek)

The OLF workgroup members provided the essential guidance and support forthe interviews and can be contacted if further information is required. Theworkgroup members were;

Torbjørn Huslende (ExxonMobil)Nils Kjær (Norsk Hydro)Stig Mjøen (Statoil)Erik Vogsberg (Enterprise/Shell)

Stavanger 20.9.02

David LlewelynWorkgroup Facilitator OLF



Contents

1. Executive Summary 3

2. Introduction 4

3. Aims and objectives 4

4. Methodology 4

5. Key Issues Raised and Resolved / Lessons Learned 6

6. Industry Challenges 17

7. Norwegian FPSO Successes 23

8. UKCS FPSO Lessons Learned 25

Appendix1 Home Page 27

Table 1 Summary of Key Issues, Lessons learned and Challenges 28

Table 2 Database of Norwegian FPSO Key Issues & Lessons Learned 37

Table 3 Norwegian FPSO Successes 66

Table 4: Most widely reported issues/problems relating to UKCS FPSO’s 67

Table 5: UK FPSO Checklist 68



1. Executive Summary

In April/May 2002 the Norwegian Oil Industry Association (OLF) initiated a research project to collect specific lessons learned from the operation of five Norwegian Floating Production Storage and Offloading vessels (FPSO’s).

Using a structured survey tool the project team interviewed 23 representatives of ExxonMobil, Norsk Hydro, Statoil and DNV.

Interviewees included 3 OIMs, 5 Maintenance Superintendents, 2 ProductionSupervisors, 2 Operations Superintendents, 6 FPSOs specialists, 4 ProjectManagement specialists and 1 DNV representative.

The findings were jointly written up by the project team against 64 topics and categorised for importance and underlying causes.

The major output of this exercise to date is the creation of a comprehensive database of issues and problems that the Norwegian FPSO sector has faced up to and resolved and the key lessons learned.

The most significant of these issues and related lessons learned are summarised in Chapter 5 and the Appendix Table 1.

More comprehensive details of the issues/problems, remedial actions and lessons learned are presented in the Appendix, Table 2.

Approximately 350 FPSO related issues/problems were reported. Where the primary underlying cause was identified the percentage number of attributions were design issues (63%), operational issues (16%), construction issues (12%), and commissioning issues (9%). It would appear that during the first 18 months problems are often down to poor construction and commissioning after that issues are usually attributable to design.

Respondents highlighted 21 significant challenges that the FPSO community faced.It is recommended that each of these issues presented in Chapter 6 and Appendix, Table 1 should be the subject of further consideration to determine the best way to jointly overcome that challenge.

Most lessons learned arise from the experience of problem resolution. Althoughselected feedback on Norwegian FPSO successes is presented in Chapter 7 andAppendix, Table 3; this was not the primary emphasis in the information collectionand respondents feedback.

A similar research exercise into lessons learned was undertaken for UKCS FPSO’s in

2001. In Chapter 8 and Appendix Tables 4 and 5 some general and selected links have been drawn between the Norwegian and UK experiences.



2. Introduction

The Norwegian Oil Industry Association (OLF) initiated this preliminary researchexercise. It was undertaken by David Llewelyn (OLF Project Manager, Stavanger), MarkCapsey (General Manager, Offshore Management Centre, Robert Gordon University,Aberdeen) and Erik Dyrkoren (Research Engineer, Norwegian Marine TechnologyResearch Institute, Trondheim).

3. Aims & Objectives

The purpose of this joint industry initiative has been to collect lessons learned from theexperiences of operators of Norwegian Floating Production Storage and Offloadingvessels (FPSO’s). Information was collected from three operators responsible for fiveFPSO’s; ExxonMobil (Balder & Jotun A), Norsk Hydro (Varg) and Statoil (Asgård &Norne) and the DNV. The objective has been to ensure that project and operatingexperience is not lost but that generic lessons learned are widely disseminated to allowcontinuous improvement, to assist common problem resolution and to seek to minimiserepetition of mistakes.

4. Methodology

The project team together with contributions from the participating companyrepresentatives identified a suite of categories of FPSO issues for investigation. Thesewere formatted into a survey tool under seven main headings: Hull & Marine; Turret;Layout; Project Management; Operations & Support; Codes/Classification; Manning &Safety. The survey tool invited respondents to identify issues/problems related toFPSO’s, to rank their relative level of importance, and to identify the underlying cause aseither design, construction, commissioning or operational related. Where remedialactions had been undertaken comments on the effectiveness of these were invited.Finally respondents were asked to comment on any lessons learned.

Experience suggests that the most valuable feedback is derived from respondents whohave had a chance to consider the subject matter in advance. Therefore the survey toolwas issued for completion to the interviewees some days prior to their formal interviewsas a catalyst for meaningful discussion. It was observed however that the majority ofparticipants had not completed the form before their interview, but preferred to‘brainstorm’ on the day.

Between 22-26 April 2002 the project team met with and interviewed 23 representativesof ExxonMobil, Norsk Hydro, Statoil and DNV in Stavanger, Sandvika and Stordal plus avideoconference with Harstad.



The project team would like to thank all the participating companies for the excellenttimetabling arrangements and the useful feedback supplied by all their representatives.

Once reviewed the interviewee’s comments were collated by FPSO Company. Thesewere then returned to each participating company for any additional feedbackcomments and amendments. To maintain client confidentiality in this final report allindications of information source including specific FPSO references and mentions ofvendors have been removed.

Part of this project has also involved linking the Norwegian FPSO experience withinformation collected by the Robert Gordon University, Offshore Management Centre fora UK FPSO research exercise conducted in 2001.

In this exercise a substantial amount of information related to FPSO operations has beengathered. To best review the data it is recommended that the Appendix beviewed on-line. A large number of hyperlinks have been created to assist users tomove from one data set to another. The Norwegian interview notes have beenevaluated and synthesised by the project team and compiled into a simple MS Exceldatabase. From this considerable information set a summary of the key issues, lessonslearned and challenges still to be faced have been compiled in Table 1. The bulk of theraw data on which this interpretation is based is presented in Table 2. Where given,insights into the perceived successes of Norwegian FPSO projects are documented inTable 3.

The most widely reported issues/problems relating to UK FPSO’s are presented in Table4. A particularly useful output from the UK research exercise was a checklist of design,construction, commissioning and operational issues, which if acknowledged might assistavoidance of decisions, and actions, that potentially could lead to problems during start-up and operations. A version of this is reproduced in Table 5 with hyperlinks to theNorwegian case study material.



5. Key Issues Raised & Resolved / Lessons Learned

In identifying issues/problems faced in the operation of their FPSO’s, respondents wereasked to rank them from 0 (not an issue) to 4 (critical issue) with respect to their overalllevel of importance. Summaries of those issues perceived as critical (4), major (3) andmoderate (2) are given below and have also been highlighted in the appendix.

Hull & Marine

A total of 172 hull and marine related issues/problems were reported. Where theprimary underlying cause was identified the number of attributions were design issues(97), construction issues (20), operational issues (16) and commissioning issues (3).

Green Water (Critical)Green water has affected 4 out of 5 FPSO’s. Waves over the bows have damagedstairways and broken accommodation windows. Waves along the side have damagedancillary equipment including fire stations, cable trays and pipework. Model testing andenvironmental predictions appear to have been inadequate to allow designers toeliminate these green water effects.

Retroactive repairs/redesign including the fitting of side panels, raising bow walls andmoving sensitive equipment appear to have reduced the problem. In some cases cargolimits have been imposed. A joint North Sea workgroup including the authorities andclassification societies has now led to a greater understanding of green water designrequirements.

Hull - Strength (Critical)3 out of 5 FPSO’s have experienced internal cracks between tanks. Cracks weredetected through minor leaks. No leakage has occurred outside the hull. In each case aprogramme of inspection and repair has been initiated. This involves taking the affectedtanks and adjacent tanks out of service, making a manned entry and after cleaning,fitting appropriate stiffeners.

Conventional hull design and basic fatigue analysis has been unable to eliminate FPSOhull cracking in service. While this is not unusual for trading vessels the operationalproblems and costs of offshore repair make this situation undesirable. Future hulldesigns should make use of fatigue analysis in all critical and high-risk areas withconstruction detail subject to high levels of control.

Accommodation (critical)The FPSO accommodation has insufficient beds (4 out of 5 FPSO’s). The situation isworsened by recent proposals from the unions that two people should not sleep in the



same cabin simultaneously. This lack of beds seriously hampers summer maintenanceprogrammes and delays major repairs or upgrades.

The economic impact of limited accommodation on operations and project (start-up andupgrades) is likely to be significantly greater than the cost of the extra beds andfacilities. Future FPSO’s should have 100+ usable beds and/or have provision fortemporary expansion.

Ballast & Cargo Pipework (Major)Construction standards for cargo and ballast pipework have proven inadequate forFPSO’s. Problems have included weld failures, leaks and corrosion. GRE pipework hashad to be reinforced due to inadequate jointing.

Since experiencing a number of failures in Cargo/Ballast pipework built to marinestandards in the Far East, DNV have tightened their inspection standards. This combinedwith more attention to material selection; inspectability and access should mitigate theproblem.

Corrosion & Coatings (Major)Coatings are required in the base of tanks to minimise corrosion from free water. If thiscoating fails or cracks SRB can build up causing significant pitting. This is a very difficultarea to inspect, so damage might become quite extensive before detection.

Operators should have an ongoing inspection programme of tank bottom coatings andwall thickness measurement. Highest risk areas are slops tanks, areas under solids buildup and locations where coatings may crack as a result of hull strains.

Cranes (Major)The choice of cranes - solid boom for 4 out of 5 FPSO’s was not optimum. These heavilybuilt booms are strongly affected by the wind and due to their weight, are insufficientlyresponsive when offloading a supply vessel or for working on equipment. The generalview is that these cranes were not designed for active load handling but for in-portoffloading.

A number of upgrades have been made or considered - increased hydraulic power,installation of coolers, emergency power pack, boom arc limit switches. However thesemodifications have only partially solved the problem.

Helicopters (Major)The forward positioned accommodation and helideck on all Norwegian FPSO’s is notoptimum for helicopter landing - misaligned approach, no forward visual reference-pointand increased vertical movement (cf. aft helidecks). However it does have theadvantage of clean air (no vessel-induced turbulence and no take off obstructions.



Installation of large helidecks on certain FPSO’s and provision of high-powered lightinghas helped pilots. FPSO’s can often turn across the wind to facilitate a 45-degreeapproach upwind. Reliable weather and heave monitoring equipment should always beselected. Future FPSO Helidecks should be designed and specified in consultation withhelicopter operators to take account of lessons learned on existing FPSO’s.

Hull Capacity (Major)Typical shuttle tanker (ST) capacities are 900,000bbls. For commercial reasons and tomake best use of the ST, Operators have wanted to fill the shuttle tanker. In severalcases the storage capacity of the FPSO requires the ST to wait and complete loadingwith a second hook up. As well as risking failure to connect due to weather, the extrawaiting time is expensive.

The cost benefits of increased FPSO storage volumes should be considered at theearliest opportunity in the design phase. It is likely that matching storage volumes tothe size of the planned shuttle tanker will prove the most cost-effective option.

Inert Gas System (Major)One FPSO was designed with Hydrocarbon blanketing to replace inert gas. Followingsuccessful proof of concept, this is now being extended to others. As well as eliminatingventing or flaring, it reduces use/maintenance of the inert gas generator.

This newly introduced technology has proven successful. Note: a key aspect ofhydrocarbon blanketing is O2 detection. This instrumentation must be kept in serviceand backed up at all times.

Moorings (Major)Different approaches have been taken by Norwegian FPSO’s. Use of individual anchorwinches has the advantage of facilitating winter installation, allowing activemanagement of the mooring system and enabling movement of the chain wear point.The permanently stopped design is simpler with reduced maintenance and lower capex.

It is not yet known if wear will be a problem for the permanently stopped design,however there is as yet no straightforward method to inspect the top of the chain andservice the fairlead. Good experience with such a design may lead to increased use ofthis lower cost approach. To date (other than minor drilling rig damage - bettermonitoring is required here) there have been no problems with the mooring lines andanchors.

Motion Assumptions (Major)Motion has not been a significant problem for production regularity in NorwegianFPSO’s. The key has been selection of effective level control instrumentation.Longitudinal separator placement has been successful. One FPSO was able to maintainfull production in 12m significant wave heights.



However operating experience for at least one FPSO has shown roll limits to be under-estimated. This has required an upgrade of the topsides fatigue design.

PAU Structures, Supports & Interfaces (Major)There have been a number of problems with PAU supports. These include excessivevibration of reciprocating compressors and pumps transferring noise too the hull, flexingof compressor supports, excessive PAU stiffness leading to cracks in the deck, pipeworkstresses due to moving independently from the PAU.

PAU design, supports and associated pipework are a critical area. Design must take fullaccount of vessel movement, machinery vibration, vessel role, wind and live liquidloading and construction tolerances.

Power Generation (Major)Each FPSO has a different engine combination. Wartsilla diesels while reliable andflexible have the disadvantage of design challenges for dual fuelling, high levels ofmaintenance and noise. LM 2500 engines have been the most successful for FPSO’s.The larger and newer LM 6000s have proven inappropriate for offshore use with variableloads (from thrusters) and the demands of low nox emissions and dual fuel use.

3 out of 5 FPSO’s have either inadequate power or incorrect engine sizes for efficientrunning. The best solution seems to lie in smaller gas turbine packages in combinationwith a large back-up diesel generator. Gas turbines also provide ample waste heat forcrude heating. The use of reciprocating diesels for main power has only been consideredappropriate for smaller FPSO’s.

HVAC (Moderate)There have been a number of examples of poor HVAC design. The most serious wasthe level of noise, which failed to meet Working Environment rules. Modifications afterconstruction are expensive and disruptive. Other problems are balancing difficulties,lack of external air locks; poor access for maintenance, stuck dampers and excessivedryness in the air.

HVAC design is a key area of design as a safety critical system. A contractor familiarwith North Sea conditions and Norwegian Working Environment legislation shouldmanage the work.

Selection of Marine Equipment (Moderate)Shipyards will normally fit butterfly valves on penetrations through the hull, howevertheir life is limited and they are easily damaged by marine growth. On FPSO’s theseshould all be replaced by gate valves, and provision made to blank these off externallyfor service



Workshops (Moderate)Workshop design and locations vary on the FPSO’s. The most successful are accessiblevia forklift, on the same level and close to stores, well equipped with mechanicalhandling equipment, separate from the accommodation (for noise) and in a safe areaallowing welding (forward).

Getting the workshop design right is important for maintenance efficiency and crewmorale. The working environment, access and conditions in the workshop will reducerepair costs, as the crew becomes confident to repair and service equipment on board.

Turret

A total of 30 turret related issues/problems were reported. Where the primaryunderlying cause was identified the number of attributions were design issues (15),operational issues (5) and construction issues (2).

Turret Location (Critical)The turret location is a key design issue. With the turret at greater than 75% of overallhull length from the stern, the vessel weather-vanes free. At around 65% (4 out of 5FPSO’s), thrusters are required to maintain/control heading. The controlled headingFPSO’s have the advantage of being able to lock the turret and thereby reduce bearingand swivel wear. However this places a demand on the thrusters (which are safetycritical) and the crew to mange turret repositioning.

Experience to date from the single Norwegian FPSO with a free turret indicates lowermaintenance and crew involvement than with the other FPSO’s. In addition that FPSOhas managed to achieve adequate safety of the accommodation forward of the turret,by using a firewall. Current experience suggests that a free turret with swivel andthrusters used for offloading only, results in the lowest Opex.

Turret Design (Critical)Three types of turret bearings are used by the 5 FPSO’s. 2 out of 3 types have beentroublesome. The wheel and rail type have proven unsatisfactory due to high pointloading from the wheels, excess construction tolerances, vessel deflection, poor rail heattreatment leading to surface cracking and inadequate wheel lubrication. The hydraulicturret bearings have suffered from pad wear, high starting friction, gripper failures,hydraulic imbalance and difficulty to access and repair components.

Turret bearing design has evolved over time. While simple rails and wheels have proveninadequate, heavy duty rails and multiple bogies with rubber pads to spread the loadhave proven an effective solution. Hydraulic pads were selected to deal with highmooring loads on a large turret. While this has been effective leading to no downtime,



maintenance has been excessive. A key learning from all designs is the need to make allcomponents easily serviceable and replaceable.

Risers (Major)Risers are a critical component of the FPSO system. Damage to the outer sheath andseawater ingress can reduce fatigue life significantly. Gas permeation can haveunexpected effects including collapse, and HP gas flow can cause vibration or looseningof the inner carcass. To date however, there have been no catastrophic failures of risers.

Good riser design and operational management is a key success factor. Monitoringsystems, the ability to flush the annulus and protect the riser from damage, particularlyon installation are needed to ensure long and trouble free life.

Swivels (Major)Overall the performance of swivels on the 3 FPSO’s has been good. There have been nosignificant leaks; the only major problem was two failures and an explosion in the oilfilled 11KV-power transfer swivel. This was due to water entering the insulation oilmedium.

Initial worries about swivel reliability have now been reduced. However, only one FPSOhas continuous swivel movement (free turret) and this has only been in service twoyears, so long term wear concerns and repair methods remain untested.

Drag Chains (Major)2 out of 5 FPSO’s have drag chains as an alternative to a swivel. Specific problemsexperienced include hose and electric cable failure due to wear from bending, wear padsworn out, difficulty of access, and damage caused by running into the end stops. Inaddition the drag chain limits the free rotation of the vessel requiring thrusters to beserviceable at all times.

While simpler than swivels, high maintenance and operability problems have indicatedthat swivels would have been a better option. This is endorsed by one FPSO where theoperator has elected to replace the gas transfer hose with a swivel.

Layout

A total of 19 layout related issues/problems were reported. Where the primaryunderlying cause was identified the number of attributions were design issues (12),commissioning issues (2) and operational issues (1).



Layout (Critical)The layout of equipment on an FPSO is a critical design phase. Concerns noted includeplacing main generators too close to the accommodation, poor mechanical handlingsolutions, exhaust and flare radiation problems, module overcrowding when others arevery spacious, poorly placed vents, access and escape routes restricted by cable andpipework, poor workshop and store locations.

It is recommended that when a basic FPSO layout is outlined more time is spent with allinterested parties both informally and through formal design reviews to ensure the bestcompromises are achieved. Relevant specialists must carefully consider all Capex, Opexand Safety issues.

Vents & Exhausts (Moderate)All FPSO’s have had problems with cold venting of hydrocarbons tripping the process.Modifications have involved routing all vents up the flare stack or, on the thrustercontrolled FPSO’s, on the downwind side.

More attention should be paid at the design stage to any source of hydrocarbon venting.This requires a significantly different approach from a trading tanker. Minor releasescan be cold vented but lines need to be located and sized to minimise any risk ofexplosion or tripping gas detectors under any weather conditions.

Project Management

A total of 29-project management related issues/problems were reported. Where theprimary underlying cause was identified the number of attributions were design issues(11), commissioning issues (6) and construction issues (4).

Capex Overruns and Schedule delays(Critical)On only one FPSO capex over-runs were avoided. In this case contract terms werefollowed with minimum change. This kept costs under control, however the Operatoradmits quality was poorer than expected and opportunities to improve the design at lowcost were missed. On the remaining projects costs over-ran significantly but the qualitywas higher than the original specification and design improvements implemented.

Almost all FPSO projects in the 90s were underbid by the main contractor. The Operatorcan either participate actively implementing upgrades when poor quality or low costsolutions are offered, or impose the contractual terms. In general an optimum balancecan be struck by working with the contractor to maintain quality and provide assistanceto improve efficiency.



Construction Management (Major)In several cases the build contract specified functional requirements, however thedesign contractor and shipyard were unable to interpret these correctly. In addition theyfailed to manage builders and suppliers to adequate quality standards, or to keep withinbudget or time schedule.

Functional specifications generally give the yard and designers too little guidance. Morework should be done up front on the selection of key equipment and specification ofquality. In all 5 cases the operator has had to provide significant resources to supportthe project or in 3 cases take over responsibility for completing the project.

Project Input from Other Groups (Major)There is evidence that builders and contractors learn a great deal during projects. Thereis therefore a real advantage in building a second or third vessel in a yard, where manyof the original problems have been worked out. However this learning appears to beshort term, as people and teams are often moved to other areas of activity.

There are advantages in repeat orders due to organisational learning, however ifworkloads are high, there is the risk that a new team with little experience will have tostart at the bottom of the learning curve again.

Operations & Support

A total of 74 hull and marine related issues/problems were reported. Where the primaryunderlying cause was identified the number of attributions were design issues (20),operational issues (17) commissioning issues (9) and construction issues (4).

CompressionA). (Critical) 3 out of 5 FPSO’s had serious compression problems (gas seal failures,repeated bundle change-outs and cracked pistons) due to undersized scrubbers andliquid carry-over. Upgrades, improved instrumentation and online equipment monitoringsolved problems. The cost of these failures which includes; service costs, spares, CO2tax, substitute diesel fuel, and lost gas export income was substantial.

A number of factors contributed to these problems, poor instrumentation, and vesselmovement reducing efficiency of separation train, liquid hold up in pipes and sluggingand poor performance of internals. It would seem a good investment to install largerscrubbers than normal to provide a safety factor for unknowns. B). (Major) Vibration from reciprocating compressors can be a serious problem. On oneFPSO poor mounting of the compressors and failure to fit bellows and flexible hoses hasled to an ongoing sequence of high potential leaks and failures. Vibration has also



affected the drive motors with isolating pads coming loose and damaging rotors. Noiseis also a problem for personnel.

Reciprocating compressor vibration is a key design issue. Only a competent supplier withexperience of packaging such units offshore should design such systems. Anindependent review of noise and vibration levels is recommended.

C). (Moderate) One FPSO achieved Gas Compression start-up 7 days after first oil. Thisis probably an industry record. This was achieved through comprehensive pre-start-upcommissioning work and operator training.

Gas plant commissioning should be fully completed before sailaway. Equipment shouldbe run on load with simulated gas. Operations staff involvement with commissioning,use of plant tuning simulators also with a rapid start-up.

Uptime Performance (Critical)Overall performance has been excellent. 4 out of 5 FPSO’s are delivering 95% or moreof available volumetric production. The 5th is at around 90%. While these figures werelower in the first 18 months production, regularity has generally exceeded industryexpectations.

There is a lack of fully objective data and it is too early to fully evaluate the success orfailure of different FPSO designs and operating strategies. To date high performanceshave been achieved but often at the expense of major modification and/or ongoingrepair programmes. Opex data was not available for the review.

Shuttle tanker / offloading (Major)FPSO/Shuttle tanker offloading has been very successful. One high potential and oneminor incident occurred out of approx. 1000 offloadings – the first was a contact whensome light structural damage was sustained and the second a rope round the thruster.Incidents of missed loadings due to weather have also been very few.

Lessons learned include the need to identify contact zones at the rear of the FPSO toensure damage escalation risk is minimised, improvements to hose care when sliding inand out of the shute, better procedures for handling the messenger line andidentification of critical components for maintenance/sparing.

Submersible Offloading Pumps (Moderate)Many Problems were experienced with hydraulic submersible pumps in the early phasesof operation. Problems were related to debris in the tanks and pipework and pipeworkleaks.

Hydraulic submersible pumps are highly sensitive to debris and any weaknesses in thepipework. This should be an area of special focus during commissioning. Simplermethods to access and repair submersible pumps should be also implemented.



Process (Moderate)There is often inadequate provision for sand and solids in the separation system.Although wells are predicted to be sand free, when water arrives they often producesand. It is also useful to be able to clean up wells directly through the test separator,which should have sand jetting installed.

Provision for sand and solids’ handling is generally a good long-term investment, despiteoptimistic predictions from the reservoir engineers.

Codes/Classification

A total of 16 codes/classification related issues/problems were reported. Where theprimary underlying cause was identified the number of attributions were design issues(4), and commissioning issues (2).

Manning and Safety

A total of 7 manning and safety related issues/problems were reported. Where theprimary underlying cause was identified the numbers of attributions were operationalissues (3) and commissioning issues (1).

Safety - General (Critical)There is no evidence that FPSO’s are less safe than other installations. A number ofFPSO’s reported that with a smaller crew than a platform, relationships, communicationand morale are better.

There is evidence that active attention to and reporting of hazards improves safetyawareness and thereby performance.

Crew (Major)All FPSO’s operate with a base crew of 35-40. This required a number of staffparticularly crane operators and mariners to be multi-skilled. However most FPSO’scarry typical POB levels of 55-70. This can cause significant problems for majormaintenance or upgrade projects.

A significant realisation has been importance of carrying multi-skilled mariners withinbase crew. Their experience is particularly important for emergency situations, cargomanagement/offloading and maintaining equipment exposed to sea spray and corrosion.



Motion effects on people (Moderate)Seasickness has not been reported as a major problem. People suffer for a day or sobut seem to adapt. Many people use stick-on patches as a cure. It can be more of aproblem however for visiting service personnel, and crews sent out to work in enclosedspaces such as tank cleaning.

FPSO management must continue to be sensitive to the problem this can pose forcertain individuals. Again this underlines the importance of having a core crew ofmariners on board.



6. Industry Challenges

Respondents highlighted a number of challenges that not only they, but also the FPSOcommunity in general faced.

Hull & Marine

Accommodation (Major)A means is required to increase FPSO accommodation for short periods (say 2-6months) for project or major repair/remedial work. The upgrade would have to meet allapplicable safety requirements including the provision of recreation space, lifeboat,refuge and escape facilities.

The design option selected is likely to be different for each FPSO - these may rangefrom an additional deck mounted module to beds installed in unused rooms. Lifeboatand escape facility upgrades will also be required. Close and early consultation with theworkforce will also be essential.

Caisson Systems (Major)Placement of sea water pumps deep in the hull (forward or aft of the main tanks)presents three main problems, cavitation when the vessel is at shallow draft or in roughweather, cost of installation in the hull and difficulties with access and maintenance ofthe engine.

An evaluation should be conducted into the practicality of using inboard mountedcaisson installed pumps for delivery of seawater direct to the end user. The advantageswould be reduced pipework, easy access to fire pumps, less cavitation and simpler pumpmaintenance and marine growth removal.

Mechanical Handling (Major)Mechanical handling for all operation and maintenance activities has been stronglycriticised on all 5 FPSO’s. Cranes are not optimum for working on FPSO equipment. "Asbuilt" handling systems for equipment in the hull are often inadequate. In general thevessel layouts are poorly optimised for equipment handling and storage.

It is suggested that the best practices developed from experience with - choice ofcranes, use of forklifts, layout, storage and landing areas and protection, hydraulicmanipulators, lifting beams and appliances in the hull should be documented in a "codeof practice" so in future contractors can design and optimise handling systems from theoutset.



Hull Shape (Major)Hull shape involves a number of compromises. A sharp bow increases green water asthe hull cuts through the waves, but it reduces mooring loads. However a sharp bowleaves little space for machinery, reduces storage volumes and increases complexity forbuilding. The transition zone has also been a source of cracking. Alternatively a bluntbow increases spray and wave impact and mooring loads.

Lessons have been learned with the compromises in hull shape for harsh environmentFPSO’s. These lessons need to be documented and in combination with improved modeltesting and environmental data used to design and specify the optimum FPSO shape foreach situation.

Painting (Major)All 5 FPSO’s have suffered from inadequate paintwork. The underlying problem is lack ofpriority and time allocated to this activity. Quality control of preparation and finishinghas also been lacking. Painting in Singapore has been particularly poor due to thehumid conditions. There has been a serious problem on several FPSO’s with a topsidespaint system failure in Norway - premature thickening of the paint, that has led toextensive remedial work.

Painting of FPSO’s is a critical area to ensure a low maintenance facility over a longperiod offshore. The inability to dry dock the vessel and its limited accommodationdemand that the initial paint finish is to the highest standard. However this work isoften conducted late when the pressure for sailaway is high. The challenge is todevelop painting technology and methods compatible with project demands and a 20-year offshore life.

Thrusters (Major)Service or repair of thrusters is a major challenge, particularly as reliability has not beenas high as expected. Most FPSO’s require thrusters at all times; a failure in winter couldimpact safety and production. Most thrusters have to be withdrawn externally and ROVwork is weather sensitive and high risk. Use of FPSO cranes while helpful, is not alwaysfeasible due to thruster weights and position.

Methods for removal and repair of thrusters in field need to be developed and shared.One solution for the future is that thrusters are not safety critical (this is true of oneFPSO), and thrusters should be designed for internal retrieval and service. This designhas been achieved on one FPSO.

Painting (Moderate)Painting the hull in the area of the water line will present a challenge as this is normallydone at 5-year dry dock. The vessel can be raised under light ballast however the work,if required, will be very exposed with no provision for scaffolding.



The challenge is to devise a methodology to safely clean, prepare and paint FPSO hullsat the splash zone while the vessel is on location and in production. The work must beconducted by a small crew so minimising impact on other summer maintenanceactivities.

Tank entry (Moderate)Entry to tanks for inspection and repair is proving very costly both the time andresources. Primary problems include tank washing, gas freeing, solids removal, tank andpipework isolation, and personnel access, repair and recoating methods.

Crude and ballast tanks should be designed to facilitate maintenance. This involvesspecial provisions for cleaning, venting and access. For existing FPSO’s, tools andmethodologies should be developed to improve the safety and efficiency - best practiceshould be shared.

Produced Water Disposal (Moderate) Produced water with 20ppm oil content (within allowable limits) can create a sheenwhen discharged from an FPSO in still water. This is in conflict with industry aspirationsof minimum environmental impact.

Work is required into the emulsification of produced oil in seawater and reasons for theformation of a free oil sheen. Studies should indicate an appropriate mitigation andprovide guidelines on when it's use should be necessary.

Sea Chests (Moderate)Marine growth in sea chests is a problem on all FPSO’s. It is an ideal location for marinegrowth and is difficult to clean. The ability to blank off the sea chests is also required inthe event of a leaking main seawater valve. Fitting blanking plates is also timeconsuming and weather sensitive. In addition the safety risks of relying on a singleblanking plate may be considered unacceptable.

The need for sea chests (normally used in vessels underway) needs to be reconsidered.Options that reduce opportunities for marine growth and allow blanking off in the eventof valve failure are required. Consideration should also be given to submersible pumpsin a caisson - (see above).

Power Generation (Moderate)Warstilla diesels are required to run on diesel and gas. This has proven difficult inpractice. Main concerns have been safety related, whereby HP gas has to be routed intoan engine room where the risk of fire is already high. HP fuel gas compressor designand reliability has also been a concern.

A solution is required to fundamentally improve the safety and reliability aspects ofrunning diesel engines on Natural gas.



Turret

Swivels/Tie-backs (Major)Increasingly opportunities to tie back new fields are being considered. This allowsvolumes to be maintained while the primary field reaches tail end production. There area number of constraints including available riser slots, swivel capacity or paths, ability toproduce separate streams, metering and control upgrades.

Typically the swivel and turret are the most challenging areas for upgrade. A low costmethod is required to upgrade swivel capacity and pull in new risers with minimum shutdown time.

Swivels (Moderate)While swivel repairs have not yet been required, a methodology to simplify repair andseal replacement is required. At present a repair to a key seal may take up to 5 days.

Project Management

Design Input from Operations (Major)It is agreed that Operations input a key to good design, however on 4/5 FPSO’s staffconsider operations input inadequate. Reasons are lack of an operating organisation,lack of operations experience, concern at capex over-runs, lack of data for operations tojustify more expenditure and information provided too late.

The challenge for operations staff is to be able to provide a reasoned justification forCapex vs. Opex trade offs based on past operating experience. Data must be presentedin a quantitative way and early enough to support investment decisions in appropriatedesign and quality requirements.


In Situ Repairs and Modifications (Critical)FPSO’s are placed on location for the duration of field life typically 7-20 years. Thismeans that all-major repairs, inspections and maintenance must be carried out in situ.Marine standards and codes assume periodic visits to port and occasional dry-docking.

The challenge is to revise all aspects of marine standards including quality control,material specifications, coatings, fatigue analysis, subcontractor management, andmechanical handling to take account of the need for minimum maintenance and in fieldrepair.



Process (Major)Failure of separator or coalescer internals due to sloshing is a common problem ofFPSO’s (reported by 3 out of 5). Reason is fatigue of internals due to poor support. Thecost of such failures is very high - shut down and repair costs.

It appears that suppliers have not adequately understood loads associated withseparators on FPSO’s. Work is required to define fluid loading and build an industryspecification for moving separation equipment to eliminate the problem.

Role of Vendors / OEM (Major)Primary equipment vendors have little involvement in the operation of equipment. Thishas two drawbacks, the Operator has difficulty accessing adequate specialists to assist inproblem resolution and the supplier has little opportunity to learn for operationalexperience.

The challenge is to secure a commitment for technical support or a minimumperformance level when the equipment is competitively bid and purchased. Thisrequires expectations to be set up front by the Operations team. If the supplier refusesto offer a performance level, another supplier should be preferred.

Solids Disposal (Moderate)Disposal of high solids content fluids is always a problem on an FPSO. The ability toclean up a new or treated well via the FPSO would add value over field life. In the eventof paint stripping or tank cleaning these solids could also be routed to the solids tank.

Consideration should be given to a third slops tank specifically designed for high solidsfluids and solids drop out. The tank would have easy cleanable surfaces with jettinglines and solids/slurry handling pumps.

Documentation (Moderate)Every Operator has complained of inadequate documentation. Primary problems havebeen late documentation from suppliers, missing data from subcontractors (particularlymarine suppliers), inability to get paperless systems up and running even one year afterstart-up, missing as built drawing and loop diagrams, incompatible tags and poor linksto maintenance databases.

The problem appears to arise from inadequate specification of documentationrequirements at order placement. It is also a low priority for suppliers after theequipment is delivered and paid for. Follow up is often inadequate. Differentspecifications from Operators are also a problem. This is an opportunity for a jointindustry initiative, perhaps building further on Norsok standards.



Standby Vessels (Moderate)All FPSO’s are using SBV’s in different ways, including storage, firefighting, ROVinspections, tug support during offloading and one FPSO is sharing with a Platform60kms away - and holds a large daughter craft on board.

The challenge is to share best practices and agree a common role for the vessel and it'sspecifications so that every FPSO can get best value from the vessel and achieveappropriate standby cover at most economical price.

Codes/Classification

Approvals & Safety Verification (Major)While all FPSO’s were built to Class, 4 out of 5 have now dropped Classification. Theirview is that there is little to be gained from remaining within the "marine" inspectionand approval regime offered by leading classification societies. NPD do not requireongoing classification.

There is potential value in classification, but there is a view that the societies have notkept up with the demanding design, build and manning requirements of FPSO’s. Thechallenge is for Classification Societies and Operators to tighten FPSO’s classspecifications so they become fully effective both for Operators, builders and regulators,in both build and operation phases.


7. Norwegian FPSO Successes

Evidence suggests that what goes wrong is more likely to be remembered than whatgoes right. In both the Norwegian and the UK research exercises the interviewees weremore forthcoming with information about problems and challenges faced, solutionsidentified, remedial actions undertaken and lessons learned. People were often reticentor unsure about classifying something as a success or a potential best practice. This isoften in part because of the difficulty people have in comparing their experiences withthose of others and then coming to an informed conclusion as to what is a good or badpractice or performance relative to a norm. It is hoped that these type of knowledgeexchange initiatives will in future assist FPSO specialists to report both positive andnegative experiences relative to established best practice.

Reported Norwegian success stories are highlighted in Table 3 of the Appendix. Theseinclude:

Hull & Marine

Inert Gas Systems (Major)One FPSO was designed with Hydrocarbon blanketing to replace inert gas. Followingsuccessful proof of concept, this is now being extended to others. As well as eliminatingventing or flaring, it reduces use/maintenance of the inert gas generator.

Motion Assumptions (Major)Motion has not been a significant problem for production regularity in NorwegianFPSO’s. The key has been selection of effective level control instrumentation.Longitudinal separator placement has been successful. One FPSO was able to maintainfull production in 12m significant wave heights. Motion effects on people has beenreported as a minor issue, particularly for people coming from fixed platforms.

Mooring Integrity (Major)Mooring integrity appears to have been better resolved in Norway compared with theirUK counterparts where a recent Noble Denton study suggested this was a majorproblem area.

Material Selection (Moderate)Material selection strategies that started early have had good results. Another FPSOreported that the hull is mainly carbon steel, several exotics- titanium seawater and GRPpipe have both been a success.

Turret

Swivels (Major)Overall the performance of swivels on the 3 FPSO’s has been good. There have been nosignificant leaks; the only major problem was two failures and an explosion in the oil


filled 11KV-power transfer swivel. This was due to water entering the insulation oilmedium.

Project Management

Project Learning/input (Moderate)There is evidence to suggest that a number of Norwegian FPSO projects benefitedsignificantly from knowledge sharing of lessons learned from other projects indevelopment at the same time. Operator’s staff and nominees working in the yardsduring construction and commissioning phases appear to have been adept at seekingout and implementing good practices from other operators and the DNV.


Uptime Performance (Critical)Where reported uptime performances have been excellent.

Compression Start-up (Major)One Norwegian FPSO had gas compression up and running 7 days after first oil. Thiswas claimed as an industry record and was attributed to comprehensive commissioningwork and operator training.

Shuttle tanker/offloading (Major)FPSO/Shuttle tanker offloading has been very successful. Only two minor incidentsoccurred out of approx. 1000 offloadings - one contact when some light structuraldamage was sustained and one rope round the thruster. Incidents of missed loadingsdue to weather have also been very few.

Manning & Safety

Crew OrganisationDecision to have good professional marine competency onboard has been beneficial.OIM is mariner, plus additional marine superintendents. Onshore management hasstrong confidence in offshore team to use their judgement to maintain stability androutinely undertake vessel related activities e.g. tank cleaning.

Safety PerformanceAll operators reported good FPSO safety performances, backed up by proactive safetycultures to enhance and extend good safety practices within project contractors andshipyards.


8. UK FPSO Lessons Learned

In 2001 the Offshore Management Centre at the Robert Gordon University in Aberdeencompleted a similar knowledge sharing research exercise on behalf of the FPSOcommittee of the United Kingdom Offshore Operators Association (UKOOA). Part of theresearch involved the collection of lessons learned from the first 12-18 months operationof FPSO’s on the UKCS. Like the OLF project a number of specialists representing tenFPSO’s were interviewed and their views collated. Whereas the emphasis andinformation reporting in the UK study were slightly different, it is worthwhile trying toalign some of the experiences and lessons learned from the two areas.

The main conclusions from the UK work were as follows:

• It appears that the majority of problems arose because of the way the projects werestructured and managed.

• Decision and actions taken in the design and construction phase are the mostprobable causes of problems in commissioning and early operation.

• Problems have also been caused by lack of communication between isolated groupsinvolved in design.

• The misapplication of functional specifications has led to operational problems.

• It appears that the responsibility for QA/QC was not clear and this has led toproblems with equipment delivered which was not fit for purpose.

• A major cause of early operational problems was that FPSO’s were sailed to theirlocation before their construction was complete and before their systems had beenfully tested.

• Knowledge of lessons learned does not seem to be shared readily across the UKFPSO industry. A change of attitude will probably be needed before the situation willimprove.

A synthesis of the most widely reported issues/problems relating to UKCS FPSO’s isshown in Table 4. Also shown in Table 5 are a checklist derived from informationcollected during interviews with UK operators of FPSO’s in September and October 2000.The checklist was produced to assist the avoidance of decisions and actions, which couldlead to problems during start-up and operations. Where appropriate, hyperlinks havebeen created between the UK suggestions in Table 5 and related Norwegian experiencesdocumented in Table 2.

A significant majority of FPSO related problems are attributable to the design phase.There is clear evidence from both the Norwegian and UKCS research of the existence ofcommunication problems in the design process and that input from personnel withoperational experience has been undervalued at this stage. Emphasis on initial capitalcost control and fast-tracking has lead to poor design decisions negatively impacting foryears to come on the operational efficiency of a number of FPSO’s and their workforce.


It is essential that lessons learned feedback from knowledge sharing initiatives such asthis are channelled back to the FPSO design companies and their staff. It is equallyimportant the customer maintains an adequate degree of internal competency andunderstanding to ensure the operational design specification is fully fit for purpose.

There have been a number of problematic issues common to both Norwegian and UKFPSO’s. These have included:

Crane design and mechanical handling issues. Many FPSO’s have been designed withinefficient cranes, poor crane coverage and inadequate lay-down areas, bumper barsand mechanical handling capabilities. This appears to be due to lack of familiarity ofoperational needs by designers.

Both Norwegian and UKCS FPSO’s have struggled with accommodation POB restrictions.Prioritisation of construction and engineering work presents real challenges because oflimited POB flexibility.

There are examples from both the Norwegian and UK project experiences that too muchfaith can be placed in the knowledge of the supplier. This can be a significant problem iffunctional specifications are not clarified down the supply chain. There are manyexamples of suppliers and even constructors not appreciating the distinctive nature ofFPSO operations i.e. assuming that the vessel can be taken off station and brought intoport if there are any problems. Designers have not adequately faced up to thechallenges of simplifying failed equipment removal mechanisms for FPSO’s. The changeout of power generation systems and thrusters has and will continue to represent amajor operational challenge.

Both Norwegian and UK FPSO’s have had experiences of poor quality painting andcoatings during the construction phase. When not properly addressed at the time thisfactor has the potential to create significant POB scheduling problems at a later stage.

Some problems attributable to the effects of motion have been reported from bothNorwegian and UK FPSO’s. These appear to be mainly where there has been insufficientattention to the effects of sloshing inside tanks and damage to separator internals as aconsequence of fatigue.

Vessel orientation and location of venting problems resulting in exhausts and otheremissions being blown over vessels have been experienced in both the UK and Norway.

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