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Floating Production, Storage, andOffloading (FPSO) units have beenused in the offshore industry fordecades. They have become theproduction unit of choice in anumber of regions, includingBrazil. And if analyst predictionsare correct, that picture is not likely to change in the near term.

The “Floating Production MarketReport to 2017”, published byInfield Systems, forecasts a boomover the next few years, with thenumber of installations in 2017expected to be 95% higher than in2008. While this growth in capexand the number of installations islargely driven by the increase inthe number of developments tomonetise gas in remote locations,an increasing focus on optimisingproduction from ultra-deepwaterdevelopments is another signifi-cant driver. Africa, Latin Americaand Australasia are expected toaccount for the most significantlevels of growth in terms of capexrelating to floating production system developments.

Already, there is a significant new-build program under way in

Brazil, where Petrobras anticipatesthe need for a sizable fleet of deep-water production units. While thecountry gears up for new fielddevelopment, however, there has

been recognition that there areproducing units working offshoreBrazil that have been in the fieldfor almost two decades.

A number of the country’s offshorepost-salt fields are reaching matu-rity, and the FPSOs that have beenon station since first oil are rapidlyapproaching their design lifeexpectancy. While it makes goodsense to build or convert units totackle the fields that will soon bein development, it is not economi-cally feasible to move newbuilds tomature fields to replace agingunits. With new reservoirs comingonstream through tiebacks to theseolder FPSOs, it is quite possiblethat the production vessels nowonsite in the Santos and Camposbasins could be needed in thosesame locations for another 20years.

The big question operators are fac-ing is a simple one: “Will theseunits be able to work safely foranother two decades?”

Petrobras, the largest offshoreoperator, has tackled this questionhead on. The operator wants tofind a way to safely extend the lifeof FPSOs in the field and is work-ing with the ABS Brazil OffshoreTechnology Center (BOTC) to meetthat objective, carrying out

A M E R I C A S F P S O

A new way of looking at FPSOs could allow some units to work safely beyond their design life.

BY CHRISTIANE MACHADO

Research in Brazil EvaluatesFPSO Life Extension

Mooring systems are among the critical components thatmust be evaluated carefully when considering FPSO lifeextension (photo: Andre Eichman)

The ABS-classed P-54, built in the 1990s, isone of the FPSOs working offshore Brazil

that is approaching the end of its design life (photo: Petrobras)

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research on corrosion rates inoperating conditions specific tolocal conditions.

Workshop Assesses LifeExtensionThere are many factors that affectthe survivability and longevity of afloating production unit, includingits design, structural integrity, andmaintenance. Additional factorsinclude fatigue life and environ-mental load changes. There aremajor challenges related to thehull structure of a production unitover time, and in the case ofFPSOs, these issues can be evenmore challenging because of thelarge number of onboard cargotanks that must be inspected andmaintained.

To discuss these and other keyaspects of FPSO life extension, ABSjoined other offshore industryplayers and regulatory agencies inan FPSO workshop supported byIBP (Instituto Brasileiro dePetróleo, Gás e Biocombustíveis)and the Society of PetroleumEngineers following the OTC Brasil2013 conference and exhibition, inRio de Janeiro, Brazil.

The event, “How to ExtendOperating Life”, provided a forumwhere approximately 200 attendeesfrom the offshore industry gath-ered to hear regulatory insightsprovided by Brazil’s NationalPetroleum Agency (ANP) and ABSand technical presentations from

Brazil’s primary FPSO operators –SBM and MODEC – and multina-tional energy majors Chevron,Total and Statoil, along withBrazil’s state-run Petrobras.

The primary objective of the work-shop was to facilitate discussionabout upcoming frontiers in tech-nology development and how newtechnologies might be applied toextend the service lives of FPSOsworking offshore Brazil.

Class RequirementsOne of the significant questionsconsidered at the workshop was therole of classification in the process

of FPSO life extension. Class soci-eties provide operators with criticalinformation, for example, the stepstaken in hull reassessment basedon a review of the original designcalculation results and the rela-tionship between these results andin-service inspection plans for lifeextension. Class societies also trackresults trends during a unit’s serv-ice life as well as modifications onthe design hull parameters.

Research under way at ABS BOTCencompasses local studies onFPSOs in an effort to determine theintegrity of operating units, infor-mation that will be used when out-lining the critical aspects of lifeextension and the expected scopeof work to be developed, whichincludes structures, mooring sys-tems, machinery, and stability.Another significant considerationis maintenance challenges thatwill arise due to the large numberof surveys that are required andthe impact these surveys have onengineering documentation.

A wise approach to extending FPSOlife is to map the unit’s structuralbehavior according to class rule

requirements and to develop trendcurves for each finding by accu-mulating the design and opera-tions modifications and their con-sequences on structural behaviorand global performance. Thisprocess involves reviewing theoriginal and updated design basisand existing analyses (strength,fatigue, and stability) as well asexisting in-service inspection plans(ISIPs) and inspection reportsfrom the class society and theowner as well as modification andrepair records, metocean history,and measured load history.

This way, designers, operators andthe class society can understandhow each specific critical point ofthe hull structure develops over theyears. Having this data wouldallow engineers to better predictthe future behavior of the unit andthen to better specify safety factors,reducing the number of additionalcomplex numerical simulationsand close-up surveys required.

The next steps would be a reassess-ment of the unit based on a reviewof collected data, a baseline surveyaccording to the survey plan,

A M E R I C A S F P S O

Local R&D Delivers Site-Specific ResultsABS opened the doors of its BOTC in Rio de Janeiro, Brazil, in 2010 with the goal of part-nering with local industry and universities in R&D efforts that have immediate applicationto challenges encountered in oil and gas operations offshore Brazil.

BOTC is one of five international technology centres that co-locate ABS engineers with cus-tomers. In addition to the centre in Brazil, ABS has had a Harsh Environment TechnologyCenter on the campus of Memorial University in St. John’s, Newfoundland and Labradorsince 2009; the ABS China Offshore Technology Center, which was established in partner-ship with Shanghai’s Jiaotong University in 2011; the Korea Energy Technology Center inBusan, South Korea, founded in 2012; and the ABS Singapore Offshore TechnologyCenter, which opened eight years ago and has become a key research and developmentfacility supporting developments in Southeast Asia.

Supported by the extensive resources of the ABS global technology centre in Houston, allof the technology centres work through partnerships with local industry, government, andacademia to address the industry’s most pressing technology challenges.

ABS is studying the impact modifying structural design parameters will have on an existing FPSO (photo: Petrobras)

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engineering analyses, and a modi-fied survey scope based on the find-ings. This would be followed by thedevelopment of a revised ISIP andfinally, a decision on the part of theclassification society about lifeextension.

In one FPSO life extension R&Dproject under way at BOTC, ABS isstudying the impact modifyingstructural design parameters willhave on an existing FPSO. Thesefindings are being catalogued sothey can be incorporated into a newGuide on life extension based onABS’ existing Floating ProductionInstallation (FPI) Rules to betterdefine the current critical points ofthe structure according to Surveysand Rule Requirements.

BOTC already has presented someof the preliminary results of theprescriptive Rule Requirements ofthat particular unit, and the resultsare positive, indicating that it isboth possible and productive toreassess mature FPSOs for the cur-rent FPI Rules while taking advan-tage of more sophisticated designreview tools and criteria.

The Next ChallengeThe next steps in the BOTC projectfor 2014 and 2015 are to developmethodologies for considering thenon-linear behavior of FPSO struc-tures in their current condition(including wastage and coatingconditions), the typical fracturemechanics modeling that can be

used as part of this structural inves-tigation, and recent real-time hullmonitoring as an alternative toclose-up surveys and its consequences for engineering considerations.

Meanwhile, it is important forindustry to collect more data andperiodically to reevaluate globalperformance of FPSO units so oper-ators and class societies alike canhave a clear understanding of and develop best practices forservice life monitoring and maintenance.

Toward that end, ABS throughBOTC and ABS Group are workingtogether to deliver a pilot programfor Brazilian operators. n

The Author:

Christiane Machado is Manager ofthe ABS Brazil OffshoreTechnology Center. She has morethan 20 years of experience as anaval architect, focusing on basicand detailed structural design forships and offshore structures.

A M E R I C A S F P S O

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Mapping a unit’sstructural behaviourand understandinghow each specific crit-ical point of the hullstructure developsover time can helpengineers better pre-dict future behaviourof the unit and specifysafety factors

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