OIL-IN-WATER ANALYSIS METHOD (OIWAM) JIP A Final Report for BG Group, BHP Billiton, CNR International, ChevronTexaco, DTI, Kerr-McGee, Marathon Oil UK, Shell UK,State Supervision of Mines and Talisman Energy (UK) Project No: OIW001Report No. 2005/96 Date: 4 July 2005TUV NEL Ltd Project No. OIW001Page 1 of 166 Report No. 2005/96 National Engineering Laboratory East Kilbride Glasgow G75 0QU UK Tel: 01355 220222 Fax: 01355 272999 OIL-IN-WATER ANALYSIS METHOD (OIWAM) JIP A Final Report for BG Group, BHP Billiton, CNR International, ChevronTexaco, DTI, Kerr-McGee, Marathon Oil UK, Shell UK,State Supervision of Mines and Talisman Energy (UK) Prepared by:Dr. Ming Yang.................................................. Mr Douglas McEwan.................................................. Approved by:.................................................. Dr David Stewart Date: 4 July 2005 for M Valente Managing Director TUV NEL Ltd Project No. OIW001Page 2 of 166 Report No. 2005/96 EXECUTIVE SUMMARY DuringtheperiodbetweenFebruary2004andFebruary2005,NELincollaboration withOPUSPLUSLtdcarriedoutaJointIndustryProject(JIP)entitledOil-in-Water AnalysisMethod(OIWAM).TheJIPwasinitiatedinresponsetoanOSPAR Recommendationtoimplementanewoil-in-wateranalysis referencemethodbased on using a modified version of the ISO 9377-2method (ISOMod). The Project was sponsored by the DTI in the UK, the State Supervision of Mines (acted on behalf of theMinistryEconomicAffairsandNOGEPA)intheNetherlands,andeightUK offshoreoperatorsincludingBGGroup,BHPBilliton,CNRInternational, ChevronTexaco, Kerr-McGee, Marathon Oil, Shell UK, and Talisman Energy (UK). The proposed new reference method is a gas chromatography (GC) based method, andissignificantlydifferentfromthecurrentinfrared(IR)methods.AlsoGC instruments used in the new reference method in general require much more skill to operate than the IR instruments used in the current approved methods. As a result of this,itwasthoughtthattherewouldbemanychallengesinimplementingthenew reference method. The objective of the study was to prepare both the regulators and the industry for a smooth transition from the current reference method to the new GC based reference method. Specifically the project aimed to achieve the following: To identify the best practical means to implement the new reference method To establish best practice guidelines for sample taking and handling To develop a realistic set of acceptance criteria for alternative methods Toadviseonhowtorelatedatafromthenewreferencemethodtothecurrent approved method Thestudyhasconcludedthatthebestpracticalwayforwardtoimplementthenew ISOModreferenceistousealternativemethodswhicharecalibratedagainstthe newreferencemethod.Acceptanceofthesealternativemethodsshallbeprimarily basedonhavingavalidcalibrationestablishedeitherbyanalysingcalibration standardspreparedinashorebasedlaboratoryorbyanalysingreplicateproduced watersamplestakenfromfields.Differentcalibrationapproacheshavebeen suggestedforalternativemethodsusinglaboratorybench-topanalysersandonline monitors respectively. However these approaches will need field trials to confirm their practicality. Calibrating an alternative method against the ISO Mod reference method foroil-in-wateranalysis,andensuringthecalibrationisvalidovertimewillnotbe easy. Indeed operators should be prepared to expect more effort in implementing the ISO Mod method than the current IR methods. Eightgeneralguidelineshavebeenestablishedforoilinproducedwatersample taking and handling. Proper adherence of these guidelines will minimise errors which may be resulted from improper sample taking and handling. With regard to data set continuity,forspecificinstallations,simplecorrectionfactorsmaybeestablishedto convertdatafromtheISOModmethodtoIRmethod.Howeveritisnotrealisticto expecttodevelopauniversalcorrelationorcorrectionfactorbetweenthenewISO Mod method and current IR methods across all the fields in the North Sea, because therearesignificantdifferencesbetweenthecurrentIRandthenewISOMod methodsandalsobecausetherearevariationsinthecurrentIRmethodsusedin different North Sea countries. This document is aimed at introducing a first step in the eventual implementation of the new reference method. TUV NEL Ltd Project No. OIW001Page 3 of 166 Report No. 2005/96 CONTENTSPage 1INTRODUCTION1.1Background................................................................................................... 5 1.2Objectives ...................................................................................................... 6 1.3Outline of Technical Programme ................................................................... 6 2REVIEWS 2.1Current Oil-in-Water Analysis Practices in the UK and the Netherlands....... 9 2.2Current Progress in Identifying Alternative OIW Analysis Methods.............. 12 2.3Use of the ISO 9377-2 GC-FID Method Offshore......................................... 14 2.4Availability of Suitable GC-FID Instruments.................................................. 16 2.5Onshore Laboratories with IR and GC-FID Analytical Capability.................. 18 2.6Possibility of Establishing a Secondary Reference Method.......................... 20 3SUPPORT FOR CONTINUED USE OF IR BASED REFERENCEMETHODS ..................................................................................................... 22 4ISO MOD METHOD IMPLEMENTATION APPROACHES 4.1ISO Mod Method Implementation Options.................................................... 24 4.2Laboratory Based Bench-Top Alternative Methods ....................................... 26 4.3Online Oil-in-Water Monitors......................................................................... 28 4.4Overall Implementation Approach................................................................. 29 5BEST PRACTICE FOR OFFSHORE SAMPLING AND SAMPLE HANDLING 5.1Background................................................................................................... 32 5.2Current Requirements & Practices ................................................................ 33 5.3Errors Resulting from Sampling.................................................................... 34 5.4Where Should Samples Be Taken................................................................ 34 5.5What Sampling Techniques Should Be Used............................................... 35 5.6Sample Handling........................................................................................... 39 5.7Sample Storage And Shelf Life..................................................................... 40 5.8Labelling & Documentation Requirements.................................................... 41 5.9Best Practice Guidelines............................................................................... 41 6ACCEPTANCE CRITERIA 6.1Basis of Acceptance Criteria......................................................................... 46 6.2General Calibration Issues............................................................................ 46 6.3Instrument Availability and Dealing with Failure ............................................ 48 6.4Data for Reporting......................................................................................... 49 6.5Recommended Calibration Approach for Laboratory Based Bench Top Analysers............................................................................................... 49 6.6Recommended Calibration Approach for Online Monitors............................ 53 7DATA SET CONTINUITY............................................................................... 58 7.1A Simple Correction Factor Across the North Sea......................................... 58 7.2General Approaches for Establishing a Conversion Factor.......................... 59 8FIELD EVALUATION OF THE ARJAY FLUOROCHECK 2000.................... 618.1Background of Study Work ............................................................................ 61 8.2Summary of Results...................................................................................... 61 8.3General Comments with Respect to OIWAM Guidelines.............................. 65 9CONCLUSIONS............................................................................................. 66 TUV NEL Ltd Project No. OIW001Page 4 of 166 Report No. 2005/96 10RECOMMENDATIONS FOR FUTURE WORK.............................................. 69 ABBREVIATION......................................................................................................... 70 GLOSSARY ............................................................................................................... 71 REFERENCE............................................................................................................. 72 APPENDIX 1 ISO 9377-2 GC-FID METHOD.......................................................... 75 APPENDIX 2 OSPAR ISO METHOD MODIFICATIONS ......................................... 98 APPENDIX 3 QUESTIONNAIRE FOR CURRENT OIW MONITORING/ANALYSIS PRACTICES...................................................................................... 101 APPENDIX 4 SIGNIFICANCE TESTING .................................................................. 107 APPENDIX 5 PREPARATION OF CALIBRATION CURVES A GUIDE TOBEST PRACTICE.............................................................................. 116 APPENDIX 6OSPAR DOCUMENT ON DYNAMIC CALIBRATION....................... 140 APPENDIX 7 RECOMMENDED METHOD FOR OPERATIONS OF THE ARJAY FLOUROCHECK BASED ON OPUS EXPERIENCE........................ 143 APPENDIX 8DETAILED DISCUSSION OF ARJAY METHOD DEVELOPMENTAND TRIAL RESULTS...................................................................... 148

TUV NEL Ltd Project No. OIW001Page 5 of 166 Report No. 2005/96 1INTRODUCTION 1.1Background Oilinproducedwaterisakeyparameterfortheoffshoreindustrybothforprocess control and for the purpose of reporting to the authorities.The determination of oil in producedwaterforreportinghasbeentraditionallycarriedoutusingapproved referencemethods[1-4]basedonsolventextractionfollowedbyaninfrared quantification. Whilst there are differences between the exact IR reference methods used in the different North Sea countries, these methods have been used for offshore oilinproducedwateranalysisforthelasttwodecades.Howeverduetothephase-outofFreon-113,andconcernsoverhealthandsafetyofitsreplacementsolvent Perklone(TetrachloroethyleneorTTCE),therehasbeenadrivetodevelopand adoptanewreferenceoil-in-wateranalysismethodbyboththeauthoritiesandthe offshore industry. Following the establishment of the ISO 9377-2 method [5] (also see Appendix 1) for the determination of hydrocarbons in water in 2000, there have been several studies [6-8]aimedatestablishingitssuitabilityasanewreferencemethodforthe determinationofoilinproducedwaterfortheoffshoreindustry.Howeverallthe studies have indicated that there were differences between the results from the ISO methodandthecurrentinfraredbasedmethods.Asaresultamodifiedversionof the ISO method was considered and a large comparison study [9] involving samples takenfrom58installationswascarriedoutundertheauspicesoftheOSPAROIC (Oslo-ParisCommissionOffshoreIndustryCommittee).Despitethesignificant difference observed between this method and the current Infrared methods from the latest study, the modified ISO method was recommended in 2003 [10]. Modifications to the ISO method are detailed in an OSPAR document [11] (also see Appendix 2). At the 2003 OSPAR OIC meeting it was formally agreed that the modified version of theISO9377-2GC-FID(GasChromatographyandFlameIonisationDetection) method will become the new reference method for the determination of dispersed oil in produced water offshore.It was also agreed that the method will enter into force from 1 January 2007. Asthenewmethodisinherentlydifferentfromthecurrentinfraredbasedmethods, andmoreimportantlythenewmethodisnotideallysuitedforoffshoreuse,itis recognised that there will be many practical challenges in the implementation of this new reference method. Thechallengesinimplementingthenewreferencemethodresultfromthefollowing issues: The new reference method is very different from the current IR methods and will produce different results (this has been proved by a number of different studies) Resultsobtainedfromallthecomparisonstudieshaveindicatedthatno generalised correlation could be established across the spectrum of the offshore installations between the ISO based method and the current methodsTheremaybeaneedtodetermineacorrectionfactoronaninstallationby installation basis The practical limitations of the new reference method may necessitate the use of alternative methods in the offshore environment. TUV NEL Ltd Project No. OIW001Page 6 of 166 Report No. 2005/96 Whilealternativemethods/technologiesmaybeavailable,itisnotclearat present on what basis such alternatives would be accepted by the authorities for reporting purposes It is on this basis that NEL proposed that a Joint Industry Project (JIP) be conducted topreparefortheimplementationofthenewreferencemethodandtoensurea smoothtransitionfromtheuseofthecurrentinfraredmethodtothenewreference method. 1.2Objectives TheoverallobjectiveoftheJIPwastopreparetheauthorityandtheindustryfora smoothtransitionfromtheinfraredbasedoil-in-watermethodtoamethodbased around the modified version of the ISO reference standard method.More specifically the JIP aimed to achieve the following: Toidentifythebestpracticalmeanstoimplementthenewoil-in-wateranalysis reference method Toestablishbestpracticeguidelinesforoil-in-watersampletakingandsample handling Todeveloparealisticsetofacceptancecriteriaforalternativeoil-in-water analysismethodsincludingbothbench-topandon-linemethods.Thiswill encouragetheuseofalternativemethodsforbothreportingandprocess management purposes. Toadviseonhowtorelateresultsfromthenewreferencemethod,and alternativemethods,tothecurrentapprovedmethodinordertomaintainthe continuity of data and to facilitate practical comparison of new and historical data by the regulators. 1.3Outline of Technical Programme 1.3.1 Best Practical Means of Implementing the New Reference Method Theaimherewastoestablishanoverallstrategyastohowthenewreference methodcanbeimplementedsmoothly.Thisinvolvedreviewsonthefollowing issues: Current practices AvailabilityofsuitableGC-FIDinstrumentsthatcouldbeusedforoffshore applications in either permanent or portable form AvailabilityoftherequiredskillsforoperatingGC-FIDinstrumentsonoffshore installations Thepossibilityofestablishingasecondaryreferencemethodthatiscalibrated against the current method and/or the new reference method with the view that it can then be used offshore for calibrating other alternative methods ExperienceandlessonslearnedfromusingGC-FIDmethodsforthe determination of oil-in-water analysis offshore Basic requirements for implementing the method such as frequency and number of samples to be taken Availabilityofonshorelaboratoriescapableofanalysingoil-in-watersamples according to the modified ISO GC-FID method Currentprogressinidentifyingalternativeoil-in-wateranalysismethodsby offshore operators in the North Sea or elsewhere TUV NEL Ltd Project No. OIW001Page 7 of 166 Report No. 2005/96 Resultsobtainedfromreviewingtheaboveshouldprovideaclearindicationofthe challengesofimplementationandtheguidancerequiredtoensureasmooth transition to the use of the new reference method.Three scenarios were considered while the review process is carried out.These were: Use of GC-FIDs deployed offshore in permanent or portable form Useofasecondary(nonGC-FID)referencemethodavailableforcalibrating other alternative methods Onshore GC-FID analysis for direct measurement and/or calibration of alternative methods 1.3.2 Best Practices for Sample Taking and Sample Handling Sampletakingandsamplehandlinghasbeenrecognisedasprobablythemost significantfactorthatcontributesrandomerrorsanduncertaintiesintheanalysisof offshore oil in produced water.There are some general guidelines available through a number of studies that have been carried out on this subject.These were reviewed sothatbestpracticeguidelinessuitedfortheimplementationofthenewreference method could be established. Dependingonwhatmethodswereacceptableandwheretheseweretobeused, different requirements resulted in terms of sample taking and sample handling. Guidelines were established to answer the following questions: Where should the samples be taken? Whatsamplingtechniquesshouldbeused?Thisincludedconsiderationof samplebottles,sampleprobes,sampletubingmaterial,sizeandlength,timing and ways in which samples are bottled. How should the samples be handled? What is the sample shelf-life, i.e. what is the maximum time lapse that should be allowed between sampling and analysis for the result to remain valid? What are the labelling and document requirements? Inaddition,guidanceontheuseofflorisil,sparging,sampletransportationand temperature of samples before analysis were given. 1.3.3 Acceptance Criteria for Alternative Methods In order to establish acceptance criteria for alternative oil-in-water analysis methods, itwasimportanttounderstandthekeyissuesthatwillbeaddressedwhensetting these criteria.It was also important that these criteria are reasonable and realistic. A separate set of acceptance criteria were established for both laboratory bench-top analysismethodsandon-linemonitoringmethods.Thesecriteriawereproduced with detailed consideration of the following issues: (i) Instruments / methods What are the basic requirements for oil-in-water analysis instruments and methods to beconsideredforacceptance?Theseincludedparameterssuchasaccuracy, measurement range, reproducibility, and explosion-proof rating etc. TUV NEL Ltd Project No. OIW001Page 8 of 166 Report No. 2005/96 (ii) Calibration requirements Whatistheconcentrationrangeoverwhichacalibrationcurveshouldbe constructed? Howmanycalibrationpoints(asaminimum)arerequiredforconstructinga calibration curve?For each calibration point how many samples should be prepared? What are the re-calibration requirements? How should the calibration data be fitted and applied straight line, curve and/or through the origin? What are the requirements for instrument validation and routine checks? (iii) Instrument availability and failure What is considered as instrument failure? What methods may be used to identify failing instruments? What actions should be taken when instruments are failing or have failed? How do we define instrument availability? What is considered acceptable instrument availability? What actions need to be taken when measurements are not available? What are the requirements for a back-up system? (iv) Data and reporting Whichdatashouldbereported?Inwhatformatshouldthedatabepresented?These will be particularly important when considering the acceptance of on-line oil-in-water monitors. 1.3.4 Data Set Continuity Asthetworeferencemethodswereconsideredtobeinherentlydifferentandthe recentOSPARcomparisonprojectfailedtoestablishageneralisedcorrelation betweenthetwomethods,therewillbedifficultiesinrelatingdatafromthenew method to the current one. Inordertorelateresultsfromthenewreferencemethodtothatofthecurrent method, it may be necessary that conversion factors be used to compensate for the differences between the two methods for individual installations.Advice is therefore given on how to establish such conversion factors and on what basis. Also if a secondary reference standard method is considered, the implication of using such a reference method on data interpretation was considered TUV NEL Ltd Project No. OIW001Page 9 of 166 Report No. 2005/96 2 REVIEWS 2.1 Current Oil-in-Water Analysis Practices in the UK and the Netherlands Inordertoinvestigatecurrentindustrypracticeregardingoffshoreoil-in-water analysis,aquestionnaire(seeAppendix3),wasinitiallysenttooffshoreoperators whoseinstallationswerelistedasdischargingproducedwaterintheyear2002s Environmental Emission Monitoring System database. There were 71 oil installations from 20 operators and 33 gas installations from 8 operators. Overall responses were receivedfrom14operatorscoveringatotalof60oilinstallationsand11gas installations.Aslightlymodifiedversionofthequestionnairewasalsosenttothe DutchregulatorwhothendistributedittooffshoreoperatorsintheDutchsector. Responses from the Dutch sector were received from 5 operators covering a total of 22 installations of which 5 are oil and the rest gas installations. The information was collected by the State Supervision of Mines. The questionnaire aimed to ascertain the following: Sample taking and handling practices Analysis procedures and instruments used Instrument calibration and verification proceduresAvailability of GC hardware and GC analytical skills offshore Use and / or plan for alternative laboratory methods Use and / or plan for on-line monitoring The findings are summarised below: 2.1.1 Sample Taking and Handling UK Thevastmajorityofsamplesaretakenfromtheoverboarddischargelines(all approvedbytheDTI).Forinstallationsthatdischargecontinuouslysamplesare takentwiceadayatequaltimeintervals.Allsamplesarecollectedusing500ml bottles with caps; however not all of the caps have inert liners. Sampling technique varies, with some using a quill. Sampling tube size ranges from inch to inch and in most cases made of stainless steel. Samples are often taken after running the sampling line from minute to 5 minutes, with the majority around a couple of minutes. There are also a number of installations where the sampling line runs continuously. Thevastmajorityofsamplesareacidifiedwithhydrochloricacid;acidisaddedto samplebottleseitherpriortosampletakingorafterthesamplebottleisfilled. Samplesareusuallyanalysedwithinminutes,normallyafterthesampleshave cooled to room temperature. The Netherlands 16samplesareanalysedpermonthforthosethatdischargeproducedwater continuously.Samplesaretakenusinginchtoinchstainlesssteeltubeswith someusingaquill.Bothmeasuringcylindersandbottlesareusedforcollecting samples.Samplevolumesvaryfrom250mlto1litre.Samplesareoftencollected TUV NEL Ltd Project No. OIW001Page 10 of 166 Report No. 2005/96 afterrunningthesamplinglineforminutesto5minutes.Someofthesampling lines run continuously. Approximatelyhalfofthesamplesanalysedoffshoreareacidified.Allsamplesare analysed within 48 hours (as legally required). 2.1.2 Calibration, Analysis and Verification UK Analysis instruments used for oil-in-water include Miran 1FF, InfraCal, Buck Scientific HC404 and Horiba OCMA-310. Apart from the Horiba instrument, the calibration and analysisproceduresspecifiedbytheDTIarefollowed.ForHoribainstruments,a HoribaS-316solventisused.Tetrachloroethylene(TTCE)isusedforallotherIR based methods. Instrumentsarecalibratedeitheronsitebyoperatorsoronshorebyanindependent laboratory;thisisusuallycarriedouthalfyearlywithsomemorefrequently.Inthe vast majority of cases, back extraction is used to prepare a stock reference standard usingstabilisedoil.However,oneoperatorpreparescalibrationstandardsby dissolvingoilinTTCEsolvent.Thenumberofcalibrationpointsvariesfrom5(4 standardsplusblank0)to10(9standardsplusblank0).Bothstraightlineand curve fit calibrations are in use, they may or may not always go through the origin. The use of florisil treatment is mixed. Mostinstrumentsareverifiedquarterly.Verificationisusuallydonebytaking4 duplicatesamples;twoarethenanalysedonsiteandtheothertwoaresenttoan onshore lab. When samples are taken for verification purposes, a Y shape sampling device is sometimes used, but some adopt the practice of partially filling the sample bottles in turn; others simply fill the sample bottles one by one. When the samples are sent to the onshore labs, information put on the label varies; thismayincludedate,time,platform,samplepoint/location,acidaddedornot, destination lab, analysis required, bottle unique identifier etc. The Netherlands AnalyticalinstrumentsusedincludeThermoNicoletFT-IR,PerkinElmerSpectrum one,BOMENMICHELSONMB100andOMS-1.Twodifferentapproacheshave beennoticed.OneoftheoperatorsadoptsamethodbasedonusingtheOMS-1 system. The method is then correlated to the NEN 6675 modified method [3]. Results fromtheOMS-1systemandthereferencemethodarethencomparedstatistically. TheothersfollowtheNEN6675modifiedmethoddirectly.Hexadecaneisusedfor calibration. For the OMS-1 based method, zero calibration is done daily and routine calibration checks are made weekly. Correlation between the OMS-1 and NEN 6675 mod is re-established if it is found that the difference between the OMS-1 results and the reference method results is statistically significant. For the others that follow the NEN 6675 modified method, calibration is done once or twice a year. The use of Florisil treatment is mixed. Instrumentperformanceverificationisdonedifferently.InthecaseoftheOMS-1 basedmethod,StatisticalProcessControl(SPC)isused.ResultsfromtheOMS-1 and from the reference method are compared, also a known concentration standard TUV NEL Ltd Project No. OIW001Page 11 of 166 Report No. 2005/96 solutionpreparedinacentrallaboratoryisdistributedandanalysedbytheOMS-1 quarterly. 2.1.3 Availability of GC and GC Skills Approximately 10% of installations in the UK have GCs available onsite and are used forgascompositionanalysis.Thecarriergasusedisusuallyhelium.Bottled hydrogenoron-sitegeneratedhydrogenisusedasfuelgasforaround50%ofthe GCs. Skilled GC personnel are available at these installations, but not 100%. In the Dutch sector only one out of 22 installations has got a GC instrument. 2.1.4 Alternative Methods and Online Monitoring UK OperatorsintheUKsectorhavenotbeenactivelyseekingtousealternative methods.Onlyoneoperatorisactivelyworkingonalternativelaboratory-based methods. Some sponsors consider the current JIP as a way of looking into alternative methods.Oneoperatorhascarriedoutseveraltrialswithdifferentlab-basedand onlinemethods,butdidnotproceedanyfurtherasnoreasonablecorrelationcould be established between these methods and the current DTI approved method. A few platforms (6 out of 60 covered) have already installed online monitors.

The Netherlands Out of 22 installations, only one installation has an on-line oil-in-water monitor, which hasbeenusedsofarfortesting/trialpurpose.Afewtrialshavebeenconductedin the past by two other operators, but none of them intends to install such a device in the near future. None of the five operators is currently seeking / testing an alternative method (non-IR based)inpreparationfortheimplementationoftheISO9377-2Modmethod. HowevertheoperatorwhousestheOMS-1system,whichisconsideredasan alternative to the current approved Dutch method, may use the same instrument and approach (of SPC) for implementing the new ISO 9377-2 Mod method. Overall analysis of oil-in-water (dispersed / aliphatic) in the Netherlands is generally differentfromthatintheUK.Thisisreflectedintheapprovedstandardmethod, calibration,verificationandtheuseofIRinstruments.Likemostoftheoperatorsin theUK,theyarenotkeentouseGC-FIDsoffshore,noraretheyactivelyseeking alternativemethodsatpresentinpreparingforimplementationoftheISO9377-2 Mod method. TUV NEL Ltd Project No. OIW001Page 12 of 166 Report No. 2005/96 2.2 Current Progress in Identifying Alternative OIW Analysis Methods 2.2.1 IR Method Using Freon / TTCE Replacement Solvent AnewASTMinfraredbasedoil-in-wateranalysismethodwasmadeofficialinMay 2004.This method has been designated as ASTM D 7066-04 and is based on using dimer/trimer of chlorotrifuoroethylene (S-316) [12], also called Flon. ThemethodissimilartoASTM3921-85method[13]inwhichoilisextractedby Freon-113 and then quantified using an IR instrument at a fixed wavelength of 2930 cm-1 or 3.4 microns. This method is also very similar to the present DTI approved IR method [1]. S-316wasoneofafewsolventsincludedinapreviousUKOOA/DTIstudy[7] carriedoutbyNEL/OPUS.Itsmaincompositionis1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane. The solvent seems to have been developed specifically for the use of oil-in-water analysis by Horiba in Japan who supply both laboratory and online IR based oil-in-water analysers. Further information on the solvent is given below: Chemical:1,2,3,4-tetrachloro-1,1,2,3,4,4-hexafluorobutane(95%),other components including Cl(CF2CFCl)3Cl (5%), Cl(CF2CFCl)4Cl (1%). CAS No.: 9002-83-9.Density at 25 oC: 1.75 g/ml. Water soluble: 0.033% compared to 0.017% wt of Freon at 25 oC. Fire and explosion hazard: non-flammable. Health Hazard: Does not produce genetic damage in bacterial cell cultures, does not induce chromosomal aberration in hamster CHL cells. Oral, mouse, LD50 6 g/kg;rat:LD9.2g/kg.28daysgavageinrats:theNOELis30mg/kg/dayfor males and 100 mg/kg/day for females. Hydrocarbon solvating ability: at least as good as Freon. EuropeanUnionregulatoryinformation:ListedinEINECS1987list,ECand EINECS Inventory Number: 2488477.Price: 102 per 600 ml. According to the Chairperson of the ASTM Committeewho developed the method, thesolventS-316isclass 0(minimal) forhealthandprotection(safetyglasses requiredforsafety),ithaslittleGlobalWarmingPotential(GWP).Alsoithasahigh boiling point (above 200 F), which makes it less likely to enter into the atmosphere than Freon. More importantly it is not on the Montreal Protocol list of solvents to be discontinued. InNorwayStatoilhavebeenusingtheS-316solventintheirIRmethodforthe determination of gas / condensate in water for reporting. Prior to the use of S-316, a study was carried out to find out ifS-316 could be used todirectly replace Freon in theirIRmethod.Inthestudytestswereperformedbytakingtwospotsampleson various installations, which were then analysed by the IR method using either Freon or S-316 as an extraction solvent. The IR instrument was calibrated using a mixture of crude oils from 7 installations. IR results were obtained both before and after the clean-up of polar components. These results are shown in the Figure 1 and Figure 2. A seven percent difference between the use of Flon and Freon is probably within the IRmethodreproducibility.Onthisbasis,theuseofFlonintheIRmethodmaybe accepted without even applying the correction factor. TUV NEL Ltd Project No. OIW001Page 13 of 166 Report No. 2005/96 Figure1CorrelationbetweenIR resultsusingS-316andFreonafter polar components have been removed (Courtesy of Statoil) [14] Figure2CorrelationbetweenIR resultsusingS-316andFreonbefore polar components have been removed (Courtesy of Statoil) [14] A key issue with S-316 is the cost. In the UK currently the price is about 10 times that of TTCE. For a discharge point, assuming two samples are taken and analysed per day, (730 samples per year), it is estimated that about 58 litres of the S-316 solvent isrequired,whichmaycostabout10K(comparedtoabout1kusingTTCE). Howeverthismaybereducediftheusedsolventcanberecycled.Asolvent reclaimernamedHoribaSR-300,whichcosts12kintheUKisavailablefrom Horiba.AccordingtoHoribathesolventcanbere-used3or4timesusingthe reclaimer. 2.2.2 Other Developments IntheUK,TalismanEnergy(UK)Ltdhascarriedoutfieldevaluationstudies comparing an Arjay UV fluorescence based oil-in-water analysis method against the DTIspecifiedIRmethod,andalsotheISO9377-2method(bothoriginalandMod version)[15,55].Fieldtripswereinitiallymadetosixinstallationswheresamples were taken and analysed using the respective methods. Results showed that the UV fluorescence based method correlated well with the DTI approvedmethodforfiveoutofthesixinstallations.Repeatwork(coveringthe calibration procedures used) later carried out on the single installation giving a poor initialcorrelation,showedgoodagreementbetweentheIRandArjayresults.All installations are oil producing with API gravity ranging from 30 o to 39 o (see more in Section 8). InNorwayUVfluorescencebasedmethodshavealreadybeenusedformonitoring oil in produced waters, e.g. ConocoPhilips for some of their Ekofisk platforms. AlsobothinNorwayandDenmarkInfraCalHATR(HorizontalAttenuatedTotal Reflection) instruments have been used. In this method, pentane is used as a solvent to extract oil from water samples.A fixed volume of the extract is then placed into a HATR platform, which has an infrared transmitting crystal made of cubic zirconia or a sapphirewindow.Afterevaporationofthesolvent,anIRbeamfixedatcertain wavelength is internally reflected down the ATR crystal. At each of the reflection point theIRenergyactuallypenetratesintoathinoilfilmleftaftertheevaporationofthe solvent. IR energy is then absorbed each time the IR is reflected. The amount of IR energyabsorbedisproportionaltotheamountoftheoilintheoriginalsample.A TUV NEL Ltd Project No. OIW001Page 14 of 166 Report No. 2005/96 schematicdiagramshowingtheprincipleoftheInfraCalHATRisgiveninFigure3. However the method is not thought to be suitable for analysis of gas / condensate in water samples. Figure 3 A Schematic diagram showing the working principle of the InfraCal HATR 2.3Use of the ISO 9377-2 GC-FID Method Offshore Asfarasoffshoreoil-in-wateranalysisusingtheISO9377-2GC-FIDmethodis concerned,onlyoperatorsintheNorwegiansectorhaveanyexperience.Norsk Hydro is by far the most active operator in implementing the ISO GC-FID method for producedwateroil-in-waterdetermination.Nineoftheirinstallationshavehadthe methodimplemented.ConocoPhilipshasalsoimplementedthemethodattheir Ekofisk field. 2.3.1 Summary of Norsk Hydros Experience [16-18] (i) General Overall: there are 10 GCs offshore, 4 in onshore laboratoriesDuringandbeforeimplementation:7onshorecoursesfor40personsfromoffshore labs were presented Totalcapitalcostsforthepurchaseofthe14GC-FIDs:4,2MNOK(approximately 350K). Costs on training courses were about 200 KNOK (approximately 17K) TheGC-FIDmethodwasvalidatedbyWestLabServicesinNorwayintermsof linearity,discrimination,reproducibilityandsensitivitybeforethemethodwas implemented. (ii) GC-FIDs used Instrument / model:Agilent GC 6890Column used:HP SIMDIST 15m X 0.53 mm id. 0.15 m film Carrier gas used: Helium Hydrogen: Supplied in bottle Injector: PTV injector with Gerstel cryo-cooling device (iii) Quality Control (QC) on the performance of the method QC Level 1: Monthly water samples with known amount of reference oil are prepared attheDepartmentofAnalyticalChemistryatHydrosResearchCentreandsent offshore to be analysed. The labs get feedback on the deviation from the true value. TUV NEL Ltd Project No. OIW001Page 15 of 166 Report No. 2005/96 QCLevel2:MonthlythreeGC-vialscontainingn-pentaneaddedwithaknown amountofoilarepreparedattheDepartmentofAnalyticalChemistryatHydros ResearchCentreandaresentoffshoretobeanalysed.Thelabsgetfeedbackon the deviation from the true value. QCLevel3:Hydrohasalsoestablishedaprofessionalsupportteamatthe DepartmentofAnalyticalChemistryattheResearchCentre,whichgivessupportto the offshore laboratories on oil-in-water and other discharge issues. This support can be given in 3 ways, by Telephone E-mail Hydros Intranet using Windows NetMeeting HydrothinksthatthecombinationoftelephoneandIntranetNetMeetinggivesthe supportingpersonattheResearchCentreinPorsgrunntheopportunitytooperate the offshore GC instrumentation from onshore. The supporting person can control all aspects of the GC instrument with the exception of physically changing components.By adding web cameras at both ends, the support can be enhanced. (iv) Other useful information NorskHydroconsidersthattheISOModmethodisbasedonon-columninjection, which Hydro would not recommend for offshore use. AccordingtoNorskHydro,theimplementationofISO9377-2hasbeeneasierthan originally anticipated. This was due to the following: Good planning, including purchasing of the GC-FIDsGood preparation in installation of the instruments offshore Good training provided to laboratory technicians both onshore and offshore A suitable support system to take care of the challenges after installation 2.3.2 SummaryoftheConocoPhilipsExperienceontheEkofiskInstallations [19] (i) Summary ConocoPhilipsimplementedtheISO9377-2GC-FIDmethodonitsEkofiskfield installationsin2002.Thefieldhas6platformsandtwocentrallaboratories.Both laboratories were equipped with GCs for the analysis of oil-in-water. However due to thelonganalysistime,onlyoneGCisnowinuse.Samplestakenfromthree platformsareanalysedusingtheISOmethod;samplesfromtheotherthree platforms are now analysed using an UV fluorescence based handheld instrument. (ii) Additional Information GCInstrumentused:PerkinElmerClarusAutosystemXLfittedwith Programmable Split/Splitless injection system Large volume injection is currently carried out Total routine analysis time is approximately 25 minutes Costs: before the ISO 9377-2 method was implemented, 8 technicians were sent toa3-daytrainingcoursewhichwascarriedoutbyPerkinElmeratacostof TUV NEL Ltd Project No. OIW001Page 16 of 166 Report No. 2005/96 15k NOKperpersonapproximately10kintotal.Runningcost:10kNOK (approximately 8K) per year for maintenance and operationQualitycontrol(a)onesamplepermonthissenttoWestLabforcheck.(b) thereisalsotheyearlyverificationrequirementbySFT,whichiscarriedoutby WestLabInstallationandmaintenancebySAMSI-aseparatesmallservicecompanyin Norway AccordingtoConocoPhilips,theyhavehighlyskilledandexperiencedlaboratory technicians and engineers on Ekofisk who are familiar with GCs. Whilst they have not experiencedanyparticulardifficulties,apartfromsomeequipmentbreakdown,their mainproblemwiththeGC-FIDmethodhasbeentheanalysistime,andreporting turnaround. 2.3.3 The Norwegian GC-FID Experience Overall AccordingtotheNorwegianPetroleumDirectory(NPD)website[20],theaverage concentration of oil in discharged produced water in Norway had been reduced from 21.6mg/lin2002to16.9mg/lin2003,about22%reductioninayear.Whilstthis maypartlyduetothecleaningmeasuresimplementedbytheindustry,ithasbeen acknowledgedthatthetransitiontoanewreferencemethodin2003,i.e.froman infraredbasedtotheISO9377-2GC-FIDmethod,mayhavecontributedtothe results.Thesitealsoconfirmedthattheimpactofthechangeoftheanalytical method on the results is being investigated. IfonelooksatNorwegianhistoricaloilinproducedwaterdata24.9mg/lin1999, 25.8 mg/l in 2000, 24.6mg/l in 2001 [21], between year 1999 to 2002, the reduction of oilconcentrationwas3.3mg/l(from24.9mg/lto21.6mg/l).Thereforeanaverage reductionof4.7mg/linasingleyearfrom2002to2003,coincidingwiththe implementationoftheISO9377-2GC-FIDmethod,raisesthesuspicionthatthe transition from the old IR method to the ISO method has an impact on the results. Overall,theexperiencesofoperators(includingbothNorskHydroand ConocoPhilips)intheNorwegiansectorshowthattheISO9377-2GC-FIDis implementable. Nevertheless it is also clear that there is a significant cost associated with new equipment purchase, technician training, maintenance, and also importantly thefactthatGCanalysistakeslongertoproduceresultsthanconventionalIRor indeed UV fluorescence based methods. In addition it looks very likely that the use of ISO 9377-2 method has resulted in lower measured oil in produced water figures. 2.4Availability of Suitable GC-FID Instruments 2.4.1 GC Requirements for the ISO 9377-2 GC-FID Method AccordingtotheISO9377-2Standard[5],aGCmustbeequippedwithanon-discriminating injection system and a flame ionisation detector. In addition, a data system should be suitable for integrating the total area of the gas chromatogram,compensatingforcolumnbleedingandforre-integratingafter drawing a new baseline. Concentration of the extract to 1.0 ml may be omitted if a high hydrocarbon oil index isexpectedorifalargequantity,e.g.100ulofthepartiallyornonconcentrated extract is injected by means of the so called large-volume injection systems. TUV NEL Ltd Project No. OIW001Page 17 of 166 Report No. 2005/96 2.4.2 GC-FIDs Available for the ISO Method from Leading Suppliers TherearemanyGC-FIDinstrumentsuppliersavailable.Someofthekeysuppliers have been contacted, including ATAS, Agilent, PerkinElmer, Shimadzu, Thermo and Varian.Summaryinformationobtainedfromeachofthesesuppliersregarding suitable GC-FID systems is given below: ATAS ATAS,inconjunctionwiththeNationalLaboratoryServiceoftheEnvironment Agency (EA), has developed the Anatune TPH-1 [22]. This is an automated GC-FID systemthatenablescompleteautomationoftheextractionandclean-upofwater samplesandcombinesthiswithlargevolumeinjectionintoaGC-FIDtoprovidea fullyautomatedsolution.ATASclaimedtoprovideacompleteturn-keypackage thatincludesinstallation,commissioningwithafullStandardOperationProcedures (SOP) and maintenance procedures. The system comprises: ATASGL Focus Robtic Sample Processor ATASGL Optic 2-200 Programmable Injector Agilent 6890 GC-FIDAgilent ChemStation Agilent Agilent [23] is the leading supplier of GCs in the GC market. However it has not itself workedontheISO9377GC-FIDmethod,butinsteadprovidedsuitableGCsfor others, such as ATAS, to develop complete packages for analysing oil-in-water using the ISO method. PerkinElmer PerkinElmer was one of the earliest GC suppliers who were involved in supplying GC instruments for the analysis of oil-in-water using the ISO 9377-2 method. Before the ISO Mod method was recommended by OSPAR, PerkinElmer instruments were also usedintheNorwegianOLFstudy[6],comparingtheGCmethodagainsttheIR based oil-in-water analysis method. PerkinElmerhassincerefinedtheprocedurestoeliminatethetime-consuming sample concentration stage used in the ISO method, their system includes: PerkinElmer Clarus / AutoSystem XL GC Fitted with Programmable Split/Splitless Injector and PreVent The system allows the injection of up to 100 microlitres of sample into a special large volume liner. The bulk of solvent can be purged off through the split vent. Use of the PreVenttechniqueremovestheentireconcentrationstep,andsimplifiesthebasic procedure. According to the supplier, calibration of the system is done on a weekly to monthly basis, with a run time for one sample of just 15 minutes. PerkinElmerisprobablyoneofthefewsuppliersamongtheleadingGC manufacturerswhohavespecificallyworkedontheISO9377-2MODmethod.The TUV NEL Ltd Project No. OIW001Page 18 of 166 Report No. 2005/96 development involved using two columns and two FIDs, where the light end (C7-C10) is characterised and separately quantified from the C10 to C40 [24]. Shimadzu A relatively small player in the European GC market, Shimadzu has also worked on the ISO 9377 GC-FID method for the analysis of oil-in-water [25]. Its systems include the following: Shimadzu GC-17AAF/AOC20I/S with On-Column Injection OCI -17 non discrimination injector (OCI and PTV Mode) automatic on-column injection electronic pneumatics for setting optimal linear velocity of the carrier gas complete control of heated zones and carrier gas pneumatics by PC-S/W Thermo (Finnigan) Thermo claim, that only their GC system enables a complete analytical cycle (sum of samplingtime,runtime,andcoolingtime)tobecompletedfortheISO9377-2 method in less than 5 minutes. The system comprises a Finnigan Trace GC Ultra configured with a (Split/Splitness) SSLinjector,andUltraFastoption(includingtheanalyticalcolumn)andaFast FlameIonisationDetector(FFID).TheanalysesareperformedusinganAS3000 auto-sampler to achieve maximum precision in automatic liquid injection [26]. Varian AlotoftheGCinstrumentscurrentlyusedoffshorearesuppliedbyVarian.Varian hasalsocarriedoutitsownevaluationoftheISO9377-2method.Ithasbeen suggestedthatabasicGCsystemfortheISO9377-2methodfromVarianwould comprise the following: VarianModel3800GCfittedwithModel1079PTVInjectorandaFlameIonisation Detector and optional 8400 Auto-sampler [27]. 2.4.3 GC Costs WhilstabasicGCthatcanbeusedfortheISO9377-2GC-FIDmethodmaycost about11K,thoselike AnatureTPH-1fromATASandClarus/AutoSystemXLGC from Perkin Elmer may cost as much as 27K. 2.5Onshore Laboratories with IR and GC-FID Analytical Capability Ifalternativemethodsaretobecalibratedonshoreagainstthenewreference method,orsamplesaretobesenttoonshoreforanalyses,itisimportanttoknow who can perform GC-FID oil-in-water analyses to the new ISO 9377-2 Mod reference method and who can provide a calibration service. ManylaboratoriesintheUKhavebeencontacted;theselabsmaybegroupedinto three main categories Labs already linked to the oil and gas industry Government labs and analytical labs in the water industry TUV NEL Ltd Project No. OIW001Page 19 of 166 Report No. 2005/96 Others 2.5.1 Labs Already Linked to the Oil and Gas Industry Organisationsinthisgroupwiththeiroil-in-wateranalysiscapabilitiesare summarised in Table 1. Table 1 OIW analysis capability in laboratories closely linked to O&G industry CompanyOIW Capability Using IR and GC-FID Champion TechnologyIR (InfraCal, DTI method, intends to purchase FT-IR), No GC-FID CoreLabIR (4 Mirans, 1 FT-IR, DTI method), 7 GCs but have not done any oil-in-water analysis using the ISO or its Mod method ERT(Scotland)Both FTIR and GC-FID are available. ITS Aberdeen - 3 Mirans, 1 InfraCal and 1 FTIR, and Sunbury - 3 Mirans, 2 FTIR,oneGC-FIDforoil-in-water.ManyGCsareavailableforthe analysisofparametersotherthanoil-in-water.BothDTImethodandIP methodareusedfortheanalysisofoil-in-water atITS.ITShavebeen doingtheUKOOAworkonanalysisofoil-in-water,aromaticsand aliphatics. Also involved in the OSPAR comparison project. Macaulay InstituteIR(FTIR,BluebookorIPmethod),havenotspecificallydoneanalysis workusingtheISO9377-2orModmethodbut4AgilentGC-FIDs available.InhousemethodanalysingC8-C40usingGChasbeen established OPUSIR(Miran,FTIR,BluebookandDTImethod),havecarriedoutoil-in-water analysis using both ISO 9377-2 GC-FID and its Mod method RUM ConsultancyIR(FTIR,Bluebookmethod,InfraCalhiredfortheDTImethod).No GC-FID. SGS Aberdeen1FTIR,nootherIRinstrument,DTImethodused,three peakanalysisusingtheBluebookalsoavailable.5GC-FIDs,all configured for analysis of parameters other than oil-in-water. Involved in theOSPARcomparisonstudy.GreatYarmouth1FTIR,DTImethod and also Blue Book method are used. No other IR instrument. No work on GC-FID ItisclearthatapartfromOpus,ITSandSGSwhohaveexperiencewiththeISO 9377-2 and its Mod method, no other laboratories who have close links to the oil and gas industry have analysed oil-in-water using these methods. 2.5.2 Government Labs and Analytical Labs in the Water Industry Thefollowinglabshavebeencontacted.Theiroil-in-wateranalysiscapabilityis summarised: EnvironmentAgency(EA)(England):With5laboratoriesinEngland,onlyIRis currently used for oil-in-water analysis (FTIR, Blue book method). EA spent time andmoneyworkingontheISO9377-2methodwithATAS,buthasnot implemented the method ScottishEnvironmentProtectionAgency(SEPA)(Scotland):3laboratoriesall using IR (FTIR, Blue book method), no GC-FID, not familiar with the ISO 9377-2 method SevernTrentLaboratories:IR(FTIR,BlueBookmethod),notfamiliarwiththe ISO9377-2methodbuthavein-houseGC-FIDmethodthatquantifiesC6-C40, which is loosely based on the Texas Natural Resource Conservation Commission (TNRCC) Method 1005/1006 [28]. Agilent 6890 is usedTUV NEL Ltd Project No. OIW001Page 20 of 166 Report No. 2005/96 Scottish Water:Two of its 5 labs are equipped with oil-in-water analysers. Each lab has an FTIR and GC-FID (PerkinElmer or Varian). Blue Book method is used for IR analysis and again TNRCC Method 1005/1006 has been loosely followed. ISO 9377-2 method has not been followed 2.5.3 Others EclipseScientificGroup:IR(InfraCal),GC-FID(inhousemethodquantifying C8 to C40), not familiar with the ISO 9377-2 method RobertsonResearchInternational:LikeSevernTrentLaboratories,GC-FID (TNRCC 1005/1006 method) is used for the TPH analysis of C5 to C35) ItisnowatleastfourandhalfyearssincetheISO9377-2methodwasmade available for oil-in-water analysis, however from information gathered so far there is clearindicationthatthismethodhasnotbeenwidelyadoptedbythelandbased industries such as the water and petrochemical. Even laboratories at the government agencies are not familiar with the method. Overallthereareonlyalimitednumberoforganisationswhohaveexperiencedthe useoftheISO9377-2methodforoil-in-wateranalysis.Howevermanylaboratories dohaveGC-FIDcapabilityfortheanalysisofoil-in-waterthatquantifies hydrocarbons with a different window from the ISO 9377-2 or the Mod method. 2.6Possibility of Establishing A Secondary Reference Method One of the possible considerations for implementing the ISO 9377-2 Mod method is to use a secondary reference method, which is calibrated against the new reference method, to calibrate other alternative methods for offshore use. The following three methods are thought to offer potential: (i)Supercritical Fluid Extraction and IR (SFE-IR) method (ii)Current approved IR method using TTCE (iii)Newly approved ASTM IR method ASTM D 7066-04 AcommercialSFE-IRsystemforoil-in-wateranalysishasbeenrecentlymade available[29].Anexampleofsuch asystemis showninFigure4.BothportableIR instrumentsuchastheWilksInfraCalandFTIRcanbeconnectedtotheSFE system.SFE-IR effectively uses liquid CO2 as an extraction solvent for an IR based method.Arecentevaluationstudy[30]supportedbyBP,DTIandStatoilhas confirmedthatSFE-IRismorethancapableofanalysingoilinsimulatedproduced water in the concentration range of interest to produced water discharges. Extraction efficiencyhasbeenfoundtobegenerallyinlinewiththatfromtheDTIapproved method. Themethodisenvironmentallyfriendly.Alsoitslongtermuseisassuredandit allows the continued use of the IR methods without the use of harmful solvents. The methodisstillrelativelynewandhasnotbeentestedoffshoreinthefields.Inthe recentevaluationstudy,difficultieswerealsoexperiencedinestablishingcalibration and analysis for oil-in-water samples made using heavy crude oils. Cleaning of heavy oilresidueintheSFE-IRsystemwasfoundtobetimeconsuming.Someoperators havealsoexpressedsafetyconcernsinusingahighpressureCO2vesseloffshore and more importantly on CO2 asphyxiation in the event of a leak. In addition there are no standardised procedures for such a method. TUV NEL Ltd Project No. OIW001Page 21 of 166 Report No. 2005/96 BoththecurrentIR-TTCEandthenewASTMD7066-04methodshaveapproved standards. Some operators are already using the IR + TTCE method as a reference methodforcheckingalternativessuchasUVfluorescence,e.g.Talismanand ConocoPhilips. Therefore it would be natural to consider such a method for use as a secondary reference method. The key issue will be how results correlate between the secondary method and the new reference method. Figure 4A picture showing an example of the SFE-IR system Unlike other properties such as flow or density, oil-in-water measurement is method dependent.Withoutamethodspecification,thetermoil-in-watermaybecome meaningless.Thismakesitdifficulttorelatedatafromdifferentmethodsaswas clearly demonstrated in the OSPAR Comparison project [9,10]. In terms of measurement uncertainties, there are two main aspects systematic and random,whichhavealsobeendemonstratedintheOSPARComparisonstudy. Calibrationwasconsideredasanimportantsourceforsystematicuncertaintywhile sampling was thought to be a significant source for random uncertainty. In conclusion provided that data from IR based methods can be correlated to the new reference method, or alternatively that regulators will continue to recognise the old IR based method and accept results from using the old reference method, an IR based method(eitherusingTTCEorS-316asanextractionsolvent)couldbeconsidered as a possible secondary reference method. TUV NEL Ltd Project No. OIW001Page 22 of 166 Report No. 2005/96 3 SUPPORT FOR CONTINUED USE OF IR BASED REFERENCE METHODS Since the recommendation was made by OSPAR on using the ISO Mod method as thenewreferencemethodforthedeterminationofdispersedoilinproducedwater, there have been a number of interesting developments and observations which lend support for a continued use of the current IR based reference methods.These are: (i) Development of the latest ASTM IR method - ASTM D 7066-04 As detailed in Section 2.2, a new ASTM IR reference method (ASTM D 7066-04) has been established. The method is similar to the current DTI approved IR method and also the current OSPAR IRmethod [31]. The key difference is the use of a solvent, S-316, in the ASTM method compared to TTCE in the OSPAR and DTI approved IR methods. The approval of the new ASTM IR method would allow the continued use of IR based methodforoil-in-wateranalysis.AsthesolventS-316isC-Hfree,itcouldalsobe used to directly replace TTCE in the current DTI / OSPAR IR methods. (ii) Operators happy to carry on using IR based methods SurveyresultsindicatethatUKoffshoreoperatorsarereasonablyhappycontinuing with the current IR based method. The issue of TTCE being a suspected carcinogen hasbeenappropriatelyaddressedbyimplementationofproperHSEproceduresby the offshore operators both in the UK and in the Netherlands [32,33] . (iii) Data set continuity ComparisonstudieshaveclearlyshownthattheISOModmethodisdifferentfrom theIRbasedmethods.Asaresultitwouldbemucheasierforbothoperatorsand regulatory bodies to implement the 40 mg/l (30 mg/l by 2006) performance standard and also to interpret historical data if IR methods continue.

(iv) Current ISO 9377-2 method experience DirectimplementationoftheISO9377-2methodinNorwayhasprovedtobe feasible.However,thefactthatoneoperatorhasalreadypartlyswitchedtoanUV fluorescencebasedalternativemethodandoneoperatorisnotrecommendingthe use of the ISO Mod method for direct offshore implementation confirmed the practical difficultiesoftheISOModmethodforoffshoreuse.Furthermorethereisastrong suspicionthattheimplementationoftheISO9377-2inNorwayhassignificantly contributed to the apparent large reduction in the average dispersed oil in produced water concentration observed in year 2003 (compared to the year 2002 data). (v) The development of the SFE-IR method Commercial SFE-IR systems are now available. One such system has been recently testedandevaluatedindependently[30].Resultsobtainedhaveclearlyshownthat SFE-IRiscapableofmeasuringoil-in-water,inparticularsamplespreparedusing gas/condensate and light crude oils. Further trials of the SFE-IR system are currently beingcarriedoutbyStatoilwherefieldoilinproducedwatersamplesarecollected and analysed. In addition, when the new reference method is implemented, there may be a need to establishalinkbetweenresultsfromthenewreferencemethodtothatfromthe TUV NEL Ltd Project No. OIW001Page 23 of 166 Report No. 2005/96 currentmethods.Suchalinkmayhavetobeestablishedonaninstallationby installationbasis.Toestablishsuchalinkonemayhavetotakereplicatesamples andanalysethemusingboththeIRmethodandtheISOModmethod,hence requiringtheuseoftheIRmethodsevenaftertheimplementationofthenew reference method.

ThereforeitisfeltthatthereisagoodcaseforcontinueduseoftheIRbased referencemethods.AcontinuedacceptanceoftheIRbasedmethodsafteryear 2006, will cause no disruption and will have no problem in interpreting historic data. Therefore it would be prudent for both the DTI and offshore operators to ask OSPAR to re-examine the case of continued acceptance of the IR based oil-in-water analysis reference methods after year 2006. (vi) ImplementationconsiderationsforcontinuedacceptanceoftheIRreference method FromtheUKpointofview,ifOSPARcontinuestoaccepttheIRbasedreference methods, there is little which requires to be changed in terms of implementation. Nevertheless the following points should be considered to help reduce the exposure of operators to TTCE and also to improve the current oil-in-water analysis practice: (a)Tousealternative(non-IR)oil-in-wateranalysismethods,whichare calibrated against the currently approved IR method(b)For those who intend to replace TTCE with S-316, one should initially double check if the use of S-316 will affect the results. If S-316 is to be used, recycle and re-use of the solvent should also be considered(c)To harmonise with other OSPAR nations in oil-in-water analysis procedures in terms of calibration and IR quantification (d)Tohavemoreunifiedproceduresonsampletakingandhandlingwhichis being developed in the current project (e)TodeveloptheSFE-IRtechniqueforfieldapplications,inparticular, gas/condensate and light crude oil fields TUV NEL Ltd Project No. OIW001Page 24 of 166 Report No. 2005/96 4ISO MOD METHOD IMPLEMENTATION APPROACHES 4.1 ISO Mod Method Implementation Options ToimplementtheISO9377-2Modmethod,fourpossibleoptionshavebeen considered, (1) Direct implementation by using GC-FIDs offshore (2) Direct implementation by sending all samples onshore (3)Indirectimplementationbyusinganalternativemethodcalibratedagainsta secondary non GC reference method (4)IndirectimplementationbyusinganalternativemethodcalibratedtotheISO Mod method onshore 4.1.1 Direct Implementation by Using GC-FIDs Offshore DirectimplementationoftheISOModmethodbyusingGC-FIDsoffshorewould seemthemoststraightforwardfromaregulatorypointofview.Howeverthereare potentialdifficultieswhichexcludeitfromfurtherconsideration.Thereasonsfor rejecting this option are presented in the following arguments:

-WhilsttheoriginalISOmethodhasbeensuccessfullyimplementedoffshoreby ConocoPhilips,NorskHydroandalsoothersintheNorwegiansector,thereis littlesupportfromtheNorwegiansoffshoreoperatorsexperiencefor implementing the ISO Mod method directly offshore -The ISO Mod method is less robust than the original ISO method-All operators in the UK and the Netherlands will have to purchase new GC-FIDs suitable for the analysis of oil-in-water using the ISO Mod method. In addition to the capital costs, there will also be significant running and training costs -Analysisofoil-in-waterusingGC-FIDsrequirestechnicianswithconsiderably more skills compared with the currently approved IR methods offshore -GC-FIDswillrequiretheuseofapressurisedcarriergasandalsotheuseof pressurised hydrogen; hence HSE issues need to be addressed -Analysisofoil-in-waterusingGC-FIDbasedmethodsisslow.Foroffshore operators,oil-in-wateranalysisisalsorequiredforprocesscontroland optimisation in addition to regulatory compliance monitoring -BoththeDTIandtheStateSupervisionofMineshaveindicatedthattheywere not so keen to take on this option 4.1.2 Direct Implementation by Sending All Samples Onshore From a regulatory compliance monitoring point of view, again this is a straightforward option.Samplestakenoffshorearesenttoanonshorelaboratorywheretheyare analysed directly using the established ISO Mod method. Advantages: -Onshore laboratories would be usually much better equipped and will have skilled GC specialists -AvoidstheoffshoreuseofGC-FIDsforoil-in-wateranalysisandhencethe additional costs associated with the purchase and running of these instruments-EasiertosolveproblemsandmaintaintheGC-FIDinstrumentsonshorethan offshore TUV NEL Ltd Project No. OIW001Page 25 of 166 Report No. 2005/96 Disadvantages -Needtosendallsamplestoonshorelaboratories,whichcanbeexpensiveand logistically difficult -There will be a delay in obtaining the results, taking days or even weeks-Itismostlikelythattheoperatorswillstillneedamonitor/analyserforroutine analysis offshore for the purpose of process control and monitoring If this option is to be considered further, the following should be investigated: Reduce the number of samples from currently two per day to one a day or even less. All samples send to a central laboratory where a procedure can be developed in which a large number of samples can be analysed automatically. This will reduce theoverallanalysiscostsandtheerrorswhichwouldresultfromtheusesof different laboratories. Asoffshoreroutineanalysisisstillexpectedtobecarriedoutbyoffshore operators, one should encourage the establishment of a correlation between the method used for routine analysis and the ISO Mod method. Whilstsendingsamplestoonshorelaboratoriesforoil-in-wateranalysisisfeasible, logistically it is still difficult, particularly when a large number of samples are involved. Also due to the delay in obtaining results, it is almost certain that operators will want to use a monitor / analyser for routine analysis for process control and monitoring. If such a monitor is to be used, the operators will probably want them to be calibrated anywaysothatresultsfromthesemonitorscanbedirectlyusedforreporting purpose. 4.1.3IndirectImplementationbyUsinganAlternativeMethodCalibrated Against A Secondary Non GC Reference Method WiththisoptionanonGCmethodiscalibratedagainsttheISOModmethodand then used to calibrate other alternative methods offshore. Two IR based methods, i.e. thecurrentapprovedIRandalsothenewlyavailableASTMIRmethodsare potentially suitable for such a purpose.Both methods have a relevant standard. One of the key considerations in using a secondary reference method should be that onceitiscalibratedagainsttheISOModmethod,itcanbeusedtocalibrateother alternativemethodsregardlessofthetypesofinstallations.Thereisnopointin havingasecondaryreferencemethodthatcanonlybeusedtocalibratean alternative method for a specific installation. To achieve this it may be necessary to develop a commonly accepted correlation between the secondary reference method and the ISO Mod method. One will probably have to use calibration standards made fromasyntheticoilforboththeISOModmethodandthesecondaryreference method. Provided that the correlation between the secondary reference method and ISO Mod method is accepted by the industry and regulators, this secondary reference method could then be used to calibrate other alternative methods offshore. Whilstsuchanapproachwouldmakeoffshorecalibrationofalternativemethods possible,itwillinvolvetwocalibrations.Thiscanbetimeconsumingandalsoitwill introduce larger uncertainty in the final oil-in-water results.TUV NEL Ltd Project No. OIW001Page 26 of 166 Report No. 2005/96 4.1.4 IndirectImplementationbyUsinganAlternativeMethodCalibratedto the ISO Mod Method Onshore Inthisapproach,analternativemethodisdirectlycalibratedagainsttheISOMod methodestablishedonshore.Oncethealternativemethodiscalibrated,itcanthen be used to determine oil in produced water offshore. This is considered as probably the best option for the following reasons: -Those advantages as listed in 4.1.2, plus-OnshorelaboratoriesarealreadycarryingoutcalibrationsonIRbased instruments for offshore operators.-SomeonshorelaboratorieshavealreadydoneanalysesusingtheISO9377-2 Mod method -BylimitingtheuseofGC-FIDsmainlyforcalibratingalternativemethods,the costs for the offshore operators for the implementation of the new method will be minimised. Thevariousimplementationoptionsaresummarisedinthediagramshowninthe Figure 5. Figure 5 ISO Mod method implementation options 4.2 Laboratory Based Bench-Top Alternative Methods For routine oil-in-water analysis offshore, the following four methods are considered astheleadingalternativebench-topmethods,whichmaybecalibratedagainstthe new reference method and used for reporting. UV fluorescence InfraCal HATR IR using TTCE and / or S-316 Horiba OCMA-310 AdetaileddescriptionoftheUVfluorescencetechniqueandInfraCalHATR techniquecanbefoundinareportpreparedbyNELforUKOOA[7].FortheUV fluorescence based technique, hand held instruments (see pictures in Figure 6) from Arjay Engineering and Turner Design Hydrocarbon Instruments are available. ImplementationOptions DirectIndirect ISO Mod methodGC-FID offshore ISO Mod methodonshore; samples sent/ analysed onshore Alternative method calibrated against a secondary ref.Alternative method calibrated against the ISO Mod ImpracticalLogistical issue & Routine offshore analysis required 2 stage calibration & Higher uncertaintyBest option TUV NEL Ltd Project No. OIW001Page 27 of 166 Report No. 2005/96 (a) FluoroCheck from Arjay(b) TD-500 from Turner Figure 6 Portable UV fluorescence analysers For the InfraCal HATR, the principle of operation is briefly described in section 2.2.2. A picture of the InfraCal HATR is shown in Figure 7(a). (a) HATR model (b) CVH model Figure 7 InfraCal HATR and CVH from Wilks For IR methods using TTCE and / or S-316 solvent, there are a number of portable instruments, which have already been used in the UK sector of the North Sea. These includetheWilksInfraCal(CVHmodel),Miran1FF,BuckHC404.PortableIR instrumentisalsoavailablefromDuratech(DuratechInfraredAnalyser).Picturesof these instruments are shown in Figure 7(b) and Figure 8. Miran Buck HC-404 TUV NEL Ltd Project No. OIW001Page 28 of 166 Report No. 2005/96 Duratech IR instrument Horiba OCMA-310 Figure 8 Portable IR Instruments TheHoribaOCMA-310(seeFigure8)isanuniqueinstrumentasithasabuilt-in extractionfacilityandusesaproprietarysolventS-316.Analysisiscarriedoutby injecting a fixed volumeof sample and a fixed amount of S-316 into the instrument, theinstrumentthenautomaticallycarriesoutextraction,cleaningandquantification stepstogiveanoil-in-waterconcentration.Aschematicdiagramshowingthesteps involvedintheanalysisusingOCMA-310isgiveninFigure9.Calibrationofthe instrumentiseffectivelydoneusingablanksolventsolutionandonestandard solutionataconcentrationdependingonthemeasurementrange.Thestandard solutionispreparedusingeitheraheavyoiloroilcollectedfromasiteinquestion. Horiba claims a measurement range of oil-in-water from 0 mg/l to 200 mg/l. Figure 9 Measurement process involved in the OCMA-310 OIW analysis 4.3 Online Oil-in-Water Monitors Thereareasignificantnumberofonlineoil-in-watermonitorsinthemarket. Techniques used may include the following: Focused ultrasonic acoustics Image analysis Light scattering and turbidity On-line solvent extraction and IR analysis Infrared attenuation total reflection Photoacoustic sensor TUV NEL Ltd Project No. OIW001Page 29 of 166 Report No. 2005/96 Laser induced fluorescence Spectral fluorescent signatures UV fluorescenceUV absorption Detailed descriptions of these techniques could be found in a report prepared by NEL forUKOOA[7].Inthesamereportdetailsofcommerciallyavailableinstruments, advantagesanddisadvantages,andcostinformationwerealsoreviewed.A summary of online monitoring techniques is given in the Table 2. UVfluorescenceandlightscatteringareconsideredtobethemostmatured techniquescurrentlyinuseformeasuringoilcontentofproducedwater.Forboth techniques, there are a number of systems available. Examples of these systems are shown in the Table 3. IntheNorthSeathereareanumberofinstallationsthathavebeenequippedwith online monitors using either light scattering and / or UV fluorescence. In the last few years the use of UV fluorescence systems appears to have gained popularity. UV fluorescence based instruments are generally more sensitive to the types of oils, thepresenceofproductionchemicals,andthedropletsize,butbothdissolvedand dispersedoilscanbemeasured.Lightscatteringbasedinstrumentshoweverare more sensitive to the droplet size, the presence of gas bubbles and solids. However they can not measure dissolved hydrocarbons. Hence selection of an online monitor will largely depend on the characteristics of the produced water stream. Forasuccessfulon-lineoil-in-watermonitoringapplication,thereareanumberof issues that need to be carefully considered by users and instrument suppliers. These include: Produced water characteristics Instrument selectionLocation and proper installationSampling and sample handling Calibrations (initial and routine) and maintenance 4.4 Overall Implementation Approach Havingconsideredthevariousimplementationoptions,itlooksthatthebestoption forimplementingtheISOModmethodistousealternativemethodswhichare calibratedagainsttheISOModmethod.Thisisbasedonthefollowing considerations: DirectimplementationoftheISOModmethodoffshorehaspracticaldifficulties and also implication on costs Direct implementation of the ISO Mod method by sending all samples onshore is logisticallydifficult,but moreimportantly,duetothedelayinobtaining theoil-in-waterresults,operatorwillmostprobablyneedtohaveanoil-in-wateranalysis method offshore for routine monitoring anyway UsingasecondaryreferencemethodthatiscalibratedagainsttheISOMod method,andthenusethesecondaryreferencemethodtocalibrateother alternative methods will involve two stage calibrations. Whilst it will make offshore calibrationpossible,itwillalsointroduceadditionaluncertaintiestotheoil-in-water analysis results TUV NEL Ltd Project No. OIW001Page 30 of 166 Report No. 2005/96 Table 2 Summary information on on-line oil-in-water monitoring methods [34] TechniqueDescriptionInstrumentN.S.trials and applications Comments Focused ultrasonic acoustics Anacousticbeamisfocusedontoasmallvolumeofsample.Particlesincludingoil dropletspassthroughthebeamgeneratedreflectedwaveswhicharedetectedand correlated with the concentration.Prototype On trialTransducermountedonapipe,sonotin contactwithfluids.Technologytobe proven. Image analysisBasedonusingavideocameratocaptureimagesofsamplecontainingoilandsolid particles.Byanalysingtheimageintermsofsize,shapefactorsandnumbers,itcan produce size distribution and concentration of both solid particles and oil droplets. 1 Commercial YesAbletoseevisuallyparticlesofoiland solid.Infoofoilconcentration questionable.Light scattering and turbidity When a beam of light passes through a produced water sample, the transmitted light is reducedduetoscattering,bymeasuringtheintensityifthescatteredlightorthe transmitted, it is possible to measure the oil concentration. At least 6 commercialYesMaybeaffectedbygasandsolids. Already in use offshore and many onboard ships.On-line solvent extraction and IR analysis This is an automated version of the approved IR method using commercially available instruments. At least 4 commercial NoMustuseanIRtransparentsolvent. Analysisintermittently.Affectedbysolids. But direct method. Infrared attenuation total reflection (IATR) A polymer-coated sapphire rod is made. At the centre of the rod an infrared transmitting optical fibre is placed. The fibre is then coupled to an FTIR spectrometer. When the rod isincontactwithanoilcontaminationwatersample,oilisabsorbedbythepolymer cladding.AsaresultwhenanInfraredlightistransmittedthroughthefibreoptic,IR absorptionoccurs.BydetectingtheIRlightattheexitendoneisthenpossibleto measure the oil concentration in the water sample. Prototype NoAnalysisintermittently.Stilltobeproven. But directly measure oil.Photoacoustic sensor By focusing a pulsed laser light into small volume of sample, oil absorbs the energy and creates high frequency pressure wave. This is detected and correlated to the amount of oil. PrototypePlannedStilltobeproven,inparticularforlow conc.OIWanalysis.Developcommercial type on-goingSpectral Fluorescent Signatures (SFS)SFSisbasedonmeasurementofbothexcitationandfluorescentspectrainsteadof usingafixedwavelengthintheconventionalUVfluorescencemethod.Inadditionto concentrationmeasurement,itcanbeusedtodistinguishsubstancesandsourcesof oils. 1 Commercial NoComplexsoftware,morecapabilitythan just measuring oil concentration Laser Induced Fluorescence (LIF) In many ways this is similar to the photoacoustic sensor. The differences are that in LIF, UVisfocusedintoasmallvolumeofwatersample,alsoinsteadofdetectingthehigh frequency wave, it detects the UV fluorescence intensity to quantify oil concentration.Prototype On TrialStill to be proven. Development on going. UV fluorescence Fluorescenceintensityismeasuredandcorrelatedtotheconcentrationofthetotalor aliphatichydrocarbonsprovidedthattheratioofaromatictothetotalhydrocarbons remains relatively constant.At least 4 commercial YesMaybeaffectedbygasandchemicals. Already in use. Trend of increasing use UV absorption UV absorbance is correlated to the concentration of the total or aliphatic providedthat the ratio of aromatic to the total hydrocarbons remain relatively constant. At least 2 commercialNoComplex and may be affected by Fe3+ and chemicals Notes: Costs for offshore on-line systems can vary from 25K to 100K. In comparison bench-top ones cost about 3K to 5K TUV NEL Ltd Project No. OIW001Page 31 of 166 Report No. 2005/96 Table 3 Online monitor examples TechniquesManufacturerModelSpecification and safety feature SigristOilGuardRange:0-1000ppm;Exprotectionclass Ex-p II T4 UV Fluorescence Turner DesignTD4100 XDRange: 0-1000 ppm. Class I Division I and Class I Division II. DeckmaOMD-7Range: 0-200 ppm, E EX pLight scattering RivertraceOCD Xtra0-200 ppm, IP 66, Explosion ProofEEXd or purged formats for Zone 1 Alternativeoil-in-wateranalysismethodsbasedonusingeitherlaboratorybased bench-topanalysersoronlinemonitorsareavailable.Bycalibratingthesemethods againsttheISOModmethodandestablishingavalidcorrelationbetweenan alternative method and the ISO Mod method, ISO Mod method equivalent results can beobtainedfromtheuseofthealternativemethods.Thiswillenableindirect implementation of the ISO Mod method. Thekeystepsinvolvedinthisimplementationapproachmaybesummarisedas follows: Select and procure an oil-in-water analyser suitable as an alternative method Select an onshore laboratory with experience of using the ISO Mod methodPreparetheanalysertomakesurethatitwillperformtothemanufacturers specifications. This may involve some sort of simplified calibrations. Carryoutcalibrationtestsandestablishalinearcalibrationcurve/correlation between the alternative method and the ISO Mod method Validate the calibration curve and / or perform routine calibration checks using a control chart. Put adequate measures in place to deal with instrument failure/break down Whencalibratinganalternativemethod,differentcalibrationmethodologiesmaybe allowed. These will be detailed in the Section 6. TUV NEL Ltd Project No. OIW001Page 32 of 166 Report No. 2005/96 5BEST PRACTICE FOR OFFSHORE SAMPLING AND SAMPLE HANDLING 5.1 Background Howsamplesaretakenandhowtheyarethensubsequentlyhandled,isgenerally recognised as one of the most significant factors in contributing to errors associated with the analysis of offshore oil in produced water.Studies have been carried out on thisissueinthepastandseveralpapersanddocumentspublished.Theissueis alsoreferencedinpublicationsandproceduresrelatingtoonshoreandoffshore sampling,soitisclearlyrecognisedasanimportantfactorinestablishingreliable results. Theobjectiveofthissectionistobrieflyexaminecurrentpracticesemployed offshore,butmoreimportantly,toestablishbestpracticeguidelinessuitedtothe implementationofthenewreferencemethodandanyothermethods.Current practicesarecentredonsamplingforthesolventextraction/IRspectrophotometric method, so these were examined to determine whether they require any modification for the new method.Amongst the other issues covered in this section will be: sampling locations sampling techniques sample handling sample shelf life labelling and documentation Awiderangeofliteraturehasbeenexaminedinhelpingtobuildtheguidelinesfor goodsamplingpractice,whicharepresentedlaterinthissection.Thereferences examinedincludeanalyticalmethods,technicalpapers,technicalguidelinesand technicalstandards[1,5,31,35-40].Examinationofthesereferencesrevealedthat mostoftheapplicableguidelinesarealreadypresentintheliterature,butarenot specificallywrittentocomprehensivelycoveralltheissuesrelevanttooffshore sampling. Theprocessforanalysisofanoil-in-watersampleiscomposedofthreesteps, namely: (i) collecting the produced water sample (ii)extracting the oil from the sample, and (iii) quantifying the oil extracted Eachofthesestepshasasetoferrorsassociatedwithit,whilstthissectionwill primarilyfocusonthecollectionaspect,othersamplehandlingaspectssuchas sparging, the use of florisil etc will also be covered. The potential errors in the steps are not all of the same magnitude.The collection of theproducedwatersamplehasthepotentialtointroducethelargesterrorinthe entire process, although quantifying the potential error is difficult. The quantification step is likely to be much less variable than the other two steps, as it is less prone to human error.If so, then differences in results when comparing the analysisofreplicatesetsofsamples,oneresultingfromthedefiningmethodforoil andtheotherresultingfromapotentialnewmeasurementtechnologymayresult from sampling and extraction errors not from differences in the methods. TUV NEL Ltd Project No. OIW001Page 33 of 166 Report No. 2005/96 In doing such comparisons it becomes important to account for errors introduced by the analytical steps that were not changed. Ifregulatorybodiesaretopermittheuseofalternativemethodstheyneeddataon which to determine comparability of the alternative methods.Operators who want to get an alternative method approved need data to confirm that they are in compliance withtheregulations.Theobjectiveofthissectionistoprovidebestpractice guidelines for the collection and handling of oily water samples.Only by minimising allpotentialerrors,canthetruecomparisonbetweenexistingandalternative methods be established. 5.2 Current Requirements & Practices Theanalysisofoil-in-watersamplesonoffshoreinstallationsis,atpresent,almost universallycarriedoutusingasolventextraction/IRspectrophotometricmethod.Different approved methods are in use in North Sea countries producing oil and gas offshore.Inaddition,inanumberofcountries,othertypesofanalyticalequipment have been approved for use offshore for overboard discharge monitoring. IntheUKsector,thedischargeofoiltoseaiscurrentlyregulatedthroughthe 'PreventionofOilPollutionAct1971',whichisshortlytobesupersededbythe 'OffshorePetroleumActivities(OilPollutionPreventionandControl)Regulations 2005'.POPA defines that water is to be sampled and analysed for oil content twice daily,toDTIapprovedstandard.(IntheNetherlands,samplingandanalysisof producedwaterisrequiredevery48hoursonmannedinstallationinlinewith OSPAR).Further,thelegislationstatesthatthesamplepointtobeusedmustbe approved by the DTI.In other countries, similar guidance is provided in the relevant legislation.Whilstthemethodsinthemselvesareoftendescribedindetail,less emphasis is often placed on the sampling process.Yet this is one of the main factors influencing the quality of any samples taken for analysis. As an example, Section 2 of the DTI method [1] provides some brief guidance on the method of sampling and storage, as follows: 2.1"Samples should be taken at least twice each day (24 hour period) such that they are taken at equal intervals of time". 2.2"The sampling point shall be: (i)immediately downstream of the final oil-water separation, and (ii)from, or just downstream of, a turbulent region. ThesitingofthesamplepointmustbeapprovedbytheSecretaryofState and may not be moved subsequently without permission". 2.3"Careshouldbetakentoensurethatthesampleisofadequatesizeand representative of the effluent.The sampling line/point should run continually oratleastbeflushedforoneminutebeforea500mlor1litresampleis taken". 2.4"Thebottleshouldbescrupulouslycleanandshouldnotberinsedwith effluent prior to sampling nor over-filled during sampling". TUV NEL Ltd Project No. OIW001Page 34 of 166 Report No. 2005/96 4.1"If the sample was not acidified at the time of collection, add 5 ml hydrochloric acid to the sample bottle". Interestingly,althoughtheDTImethodprovidessomeguidanceonsamplepoint location,thesamplepointdesignisnotconsidered.Also,whilstthesolvent extractionmethodiscoveredindetail,thepotentialimpactofacidificationand storage time is not mentioned. The operator survey results in Section 2 confirmed a number of issues relating to the analysisofoil-in-wateroffshore.Specificallythesewerethatthevastmajorityof installationsemployanIRspectrophotometricmethodwhichusesTTCEsolvent.Further,thevastmajorityofsamplesarebeingtakenfromtheoverboarddischarge line via the approved DTI sample point. Somerespondentsconfirmedthatcentrelinequillswereusedforsampling,whilst otherswereunsure.Samplepointswereconfirmedasbeingrunforthenecessary1-2minutespriortosampling,withsomeoperatorsrunningthesamplepoints continuously.Thevastmajorityofsampleswereconfirmedasbeingacidifiedwith hydrochloric acid, and analysis was carried out as soon as the samples were cooled down. Theoperatorsurveyconfirmedthatoperatorsarealreadyfollowingseveralofthe guidelinesspecifiedintheDTImethod.Thisinitselfisquiteencouragingandthe establishment of more formal guidelines should help improve this further. 5.3Errors Resulting from Sampling It is very difficult to actually quantify errors associated with some aspects of sampling as the errors will only reveal themselves when the differences between good and bad practice are examined.Since the actual analysis method produces the final result, if bad practice in collection of samples continues to be used without any understanding oftheimpactonthefinalresult,thennoobviouserrorswillbeapparent.Itis thereforeessentialthatgoodpracticeisadoptedinthecollectionandhandlingof samples, in order to minimise or eliminate potential errors. The error introduced, for example, by analysing a sample from a line which had not beenflushed,comparedtoonewhichhad,isverydifficulttoquantifyoreven replicate.However,itisclearthatfailuretoflushasamplelinepriortosample collectioncanadverselyaffecttheresult,soitisthusessentialthatgoodpractice guidelines are followed.Where samples may have low concentrations of oil-in-water, suchassub40mg/l,thenitisentirelypossiblethaterrorsof100%ormoremay result from failure to follow best practice. 5.4Where Should Samples Be Taken? ThecurrentDTIapprovedmethod[1]andthePARCOMmethod[31]provideclear guidance on the location for where samples should be taken for oil-in-water analysis.Thesestatethatthe samplepointshouldbedownstreamofthefinalstageofoil-in-water separation, and it should be from, or just downstream of, a turbulent region. ThePOPAlegislationalsodefinesthatthesamplepointhastobeapprovedbythe DTI, and that the sample point location cannot be moved without prior authorisation.Since the objective of this guidance is to obtain a representative sample for analysis atthepointofdischarge,therewouldappeartobenoreasontochangethese TUV NEL Ltd Project No. OIW001Page 35 of 166 Report No. 2005/96 requirementsforthetransitiontotheISO9377-2Modmethod,orindeedanyother method which has been approved for use. 5.5What Sampling Techniques Should Be Used? Thelocationofanysamplepointclearlyhasanimpactonhowrepresentativeany sample may be of the main flow.Sampling from dead legs, for example, cannot give a true indication of the main flow conditions.Similarly sampling from the top, bottom orsideofapipecanyielddifferentresults,particularlywhereoilispresentinthe water phase.However, a number of other factors can also affect how representative any sample may be, including: design of the sample point flow conditions in the pipe containing the sample point sample point condition sample bottles used Each of the above issues is considered below in further detail. Design of the sample point Assumingthecriteriaforlocationofthesamplepointaremet,thedesignofthe sample point is equally important.The design may vary depending on whether spot samples are required or an on-line oil-in-water monitor is being installed.Themain objectiveindesigninganysamplepointistoensurethatitcanprovidea representative sample, assuming all other conditions are met.For most pipework (1 and upwards), this can be achieved by the use of centre line sampling probes, such as that provided by Jiskoot [41] (see Figure 10 below).Pipewall effects mean that it isessentialtosampleatleastfromthecentre1/3rdofthepipeflow.Ideally, installationinverticalpipeswithup-flowispreferableforoilywatersamplesto minimise any potential for settlement.However, providing turbulence is maintained, installation in horizontal pipework should cause no problems. Intermsofsamplepointdesignandtheminimisationofsamplingerrorsforspot samples, the use of a completely integrated and automated sampling system should be considered. Such systems are available and in widespread use for fiscal sampling and monitoring e.g. crude oil sampling. Figure 10 Jiskoot centre line pitot sampler TUV NEL Ltd Project No. OIW001Page 36 of 166 Report No. 2005/96 Figure 11 Fast loop sampling system Thesystemscansampleusingeitherafastloop(seeFigure11)orinlinesampling system.For oil-in-water sampling, the use of such a system would have benefits in minimisingthesortsoferrorsassociatedwithsamplingfrommanualsamplepoints.However, the use of such a system on balance probably introduces an unnecessary level of complexity to the collection of oily water samples.This would also increase the need for maintenance. Providingsomesimplerulesarefollowedwithrespecttothedesignofthesample point, then representative sampling should always be attainable.These are detailed below. Wherepracticable,acentrelinepitotshouldalwaysbeused.Theseare availablecommerciallyandcanbe ofsucha designthattheycanbe withdrawn forinspection.Pitotscanalsobemadeveryeasilyusingstainlesssteeltubing.Thepitotshouldbeofatleastboreandtheedgesofthepitotshouldbe smoothed off prior to use. On older installations, where installation of centre line pitots may prove difficult, side wall sampling may be used together with a suitably designed sample point. However care needs to be taken with regard to ensuring adequate rigidity. For external valving at the sample point, there will normally be a requirement for double block and bleed valving.Ideally, full-bore sample valves should be used, suchasballvalves.Specificationsforvalvingonoffshoreinstallationsnormally means that other valve types may be required, such as needle or gate valves. Thedistancebetweenthesampleprobeandthesamplevalvingshouldalways beminimised,asthelongerthesampleline,thegreaterthechanceoferrors influencing any subsequent analysis.For example, where a sample point has not beenflushedproperly,thereisapossibilitythatoilresidueretainedwithinthe sample line will introduce an artificially high result. Where possible a dedicated flowmeter should be installed as part of the sample point, to allow the sample flow to be measured and regulated, such that isokinetic sampling can be achieved. Sample tubing requires no special guidelines, other than the material used should becompatiblewiththefluidsbeingsampled.Generally,stainlesssteelisthe preferredmaterialofchoiceoffshore,althoughspecialalloysmayberequired subject to fluid characteristics. TUV NEL Ltd Project No. OIW001Page 37 of 166 Report No. 2005/96 A schematic of an ideal sample point is shown Figure 12. 12 " STAINLESS STEEL PITOT(VARIABLE INSERTION)FLOWBALL VALVEGATE VALVE Figure 12 A schematic of an idealised sample point Where an on-line oil-in-water monitor is being considered for installation, it is just as important to consider how the system may receive a representative sample.A wide rangeofoil-in-watermonitoringtechnologyisnowavailablecommerciallyandthe natureofhowtheyoperateintermsofboththeirdetectionprincipleandmethodof sampling can vary significantly.Some systems operate using a sidestream from the mainprocess,whilstotherscanbeinstalleddirectlyintothemainpipe.Itis thereforeimportantthattheinstallationrequirementsdonotoverridetheneedto ensure effective and representative sampling. Somegeneralguidelinescanbeappliedtotheinstallationofon-linesystemssuch that representative sampling is achieved. Where on-line systems require a sidestream feed to the monitor, the feed should be provided by way of a dedicated sample connection.A centre line pitot should be used to ensure that the sample is representative.Depending on the available linepressureandthemonitorflowrequirements,thesamplemayneedtobe pumped to the monitor. Whereon-linesystemsrequiretheinstallationofaprobeinthemainpipe,the locationshouldbesuchthatthereisconfidencethattheprobeisexposedto representative flow conditions. Flow conditions in the pipe containing the sample point Variationinflowconditionscanalsoaffecthowrepresentativeasamplemaybeof the main flow.As stated earlier, the sample point should ideally be located within a turbulentzone.Iftheflowistoolow,thenitispossiblethatseparationoftheoilin the fluid will occur, leading to stratification and thus unrepresentative sampling. TUV NEL Ltd Project No. OIW001Page 38 of 166 Report No. 2005/96 Knowledge of the flow regime within the main pipe is therefore important for ensuring representative sampling. Figure 13 Examples of offshore sample points Sample point condition The condition of the sample point is important, as contamination of the sample point islikelytoleadtocontaminationofanysubsequentsamples.Atconcentrationsin the0-40mg/lrange,suchcontaminationcouldhaveamarkedimpactontheend result.Samplepointsnotincontinuoususecannaturallycausehydrocarbonsor solidsorbothtocollectwithintheprobe.Itisthereforeessentialthatadequate flushingtimebeprovidedpriortoasamplebeingtaken.Asanabsoluteminimum, the sample point should be flushed for 1 minute before a sample is taken.For ideal representative sampling, the sample point should be allowed to flow continuously to a suitabledrainontheinstallation.Thesamplepointitselfshouldbemaintainedin good working order and kept as clean as possible.On offshore installations this can prove difficult.Two examples of offshore sample points are shown in Figure 13.Sample bottles Given some of the issues discussed above with respect to sampling, it is unsurprising that sample bottle condition and cleanliness are of equal importance if representative resultsaretobeobtainedbyeithertheIRorGCmethods,orindeedanyother approved method. Foroil-in-watersampling,Pyrex(Duran)glassnarrowneckedbottlesof500ml shouldbeused.Plasticbottlesshouldneverbeused,asthehydrocarbonsinthe samplecanreadilydiffusethroughthebottle.Plasticiserscanalsoleachfromthe plastic, resulting in misleading results.A good example of the type of 500 ml bottle that should be used is shown Figure 14 below. TUV NEL Ltd Project No. OIW001Page 39 of 166 Report No. 2005/96 Figure 14 Typical oil-in-water monitoring sample