dokument5 27.03.01 15:07 side 1 environment 2001...illustration: lasse skarbøvik photos: ©Øyvind...

Environment 2001The Norwegian petroleum sector

Ministry of Petroleum and Energy

Dokument5 27.03.01 15:07 Side 1

Environment 2001


Visiting address:Einar Gerhardsen plass 1

Postal address:P O Box 8148 Dep, N-0033 Oslo

Tel +47 22 24 90 90Fax +47 22 24 95 65

http://www.oed.dep.no

E-mail: [email protected]

Telex: 21486 oedep n

The Norwegian petroleum sector

Miljø 2001 ENG orig 27.03.01 15:01 Side 3

Editor: Øystein Aadnevik, MPEEdition completed: March 2001

Layout/design: Fasett AS, www.fasett.noIllustration: Lasse SkarbøvikPhotos: ©Øyvind Hagen, ©Fredrik Refvem, Statoil,©Victor Lenson Brott, BP Amoco, Norsk Hydro,©Fotobase/Willy Haraldsen, Husmo Foto.Paper: Munken Lynx 240 g/150 g.Printer: GunnarshaugCirculation: 4 000 Norwegian / 6 000 English

ISSN-1502-3400


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Foreword

SECTION 1

Petroleum activities in Norway

Environmental protection by the authoritiesExploration phase

Development and operation phase

Closing phase

Status of emission and dischargesCarbon dioxide CO2

Nitrogen oxides NOx

Non-methane volatile organic

compounds (nmVOC)

Oil, organic compounds and chemicals

SECTION 2: DISCHARGE TO SEA

Discharge components

Discharge sources

National policy

International agreements

Assessing environmental impact

Environmental management

Technological solutions

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Contents


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The purpose of issuing this environmental publication is threefold:

• To increase the knowledge of environmental issuesin the Norwegian oil and gas sector.

• To take a closer look at a topic which both the industryand authorities are particularly concerned about,including the options and challenges faced.

• To underline the Government’s goal that Norway shouldcombine her role as a major energy producer with thatof being a leader and setting a good example on environmental matters.

"Discharge to sea" is the main topic of Environment 2001.We wish to inform about the challenges and opportunitiesfacing the industry regarding the discharge of oil, organiccompounds and chemicals.We also wish to discuss thenational policy in this area and assess any environmentalimpact such discharges could have on the marine environ-ment.To make the presentation more focused we haveconcentrated on continuous discharges to sea both fromwell and drilling operations as well as from produced water.

In addition Environment 2001 also contains a factual section.Here we deal with the state of the discharge issue,the environ-mental effects and measures to reduce the emissions to airand discharges to sea from the offshore operations.

It is our hope that this publication will help to enhancethe knowledge about the petroleum activities and what isbeing done to protect the environment.We furthermore hopeto demonstrate that concern for the environment is alreadyan integrated part of the Norwegian petroleum policy.

I would like to extend special thanks to the externalreference group comprising representatives of Bellona, theNorwegian Oil Industry Association (OLF) and the Federationof Norwegian Manufacturing Industries (TBL) for constructiveinput and comments during the work with Environment 2001.

Foreword

Yours sincerely

Olav AkselsenMinister of Petroleum and Energy


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Figure 1 Production of oil and gas on theNorwegian continental shelf. (Source: MPE/NPD/FIN)

Figure 2 Government’s net cash flow from petroleumoperations 1988-2001. (Source: MPE/NPD/FIN) *estimate

Petroleum activities in Norway

Facts about the petroleum sector

• accounted in 2000 for around 48% of the valueof Norwegian exports

• contributed 25% of the state’s overall revenues in 2000 through:- revenues from the State Direct Financial

Interest (SDFI)- taxes and duties from the oil companies- dividends from Statoil and Norsk Hydro

• Statfjord/Snorre, Gullfaks and Oseberg,which account for well over 27% of Norway’sproduction of oil, have all passed their peak levelof production and now have declining output

• none of the oil discoveries made in recent yearshas been of this magnitude

• when Draugen came on stream in 1993 it markedthe introduction of the Norwegian Sea as a production area

• gas will gradually assume increasing importancecompared with oil

Oil production on the Norwegian continental shelfstarted on the Ekofisk field in 1971. Gas exportsstarted out from the same field in 1977. Outputgrew from year to year until 1997 (see Fig. 1).In 1998, production was somewhat lower than theyear before due to diminishing production frommature fields, production regulation to contributeto stable oil prices and postponed start-ups of newfields.Production increased last year and is expectedto reach its maximum level next year.

In addition to developments on the continental shelf,shore facilities have been built at Kårstø, Kollsnes,Sture, Mongstad and Tjeldbergodden in order toland gas, and to a greater or lesser degree, processoil from the fields.

Oil and gas are non-renewable resources.The production of oil and gas often generatesrevenues far in excess of what is normal in otherindustries.These additional earnings accrue forthe most part to the government through taxes andduties as well as through the State’s direct interest.

Petroleum operations have contributed enormousrevenues to Norwegian society.Total revenues fromthe sector have varied over time in step with changes inprice and production, see Fig.2.Petroleum revenuesare to a large degree determined by the worldmarket price for crude oil, the exchange rate of thedollar and production costs.This means that thegovernment loses considerable revenues when theprice of oil is low.The government’s annual cash flowfrom the sector is reduced by an estimated NOK 1billion each time the price of oil drops by one krone.

The demand for goods and services precipitatedby activities on the Norwegian continental shelfhas created major ripple effects in society. A highpercentage of the contracts for exploration,develop-ment,production, transport and removal of obsoleteequipment have been won by Norwegian industrialcompanies in competition with internationalcompetitors.The strength Norwegian offshore suppliershave consequently gained in recent years has allowedthem to make gradual headway in the internationalmarket as well.Being competitive on the world marketis vital if the industry is to have a future beyondits lifetime on the Norwegian continental shelf.

mill

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Gas production

Oil production(incl. NGL and condensate)

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Net cash flow

1990 1992 1994 1996 1998 2000*


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Environmental protection

by the authorities

Environmental policy has historically been basedon direct regulation of environmentally harmfulemissions and discharges. In recent years Norwayhas made increasing use of economic measuressuch as taxes. In a number of other countries theauthorities have to a greater extent chosen to signagreements with the industry in order to limit theenvironmental impact of various types of emissionsand discharges.

The authorities regard close co-operation with theindustry as a precondition for achieving establishedenvironmental goals without imposing too higheconomic costs on society. In order to furtherdevelop such co-operation in the oil industry,MILJØSOK was founded in 1995.The objective ofthis environmental initiative is to maintain theNorwegian continental shelf’s position as an exponentof environmentally friendly and competitive oiland gas activities in the future. Oil companies, thecontracting industry, authorities and other affectedgroups are all a part of the effort.

Exploration phaseThe objective of opening new exploration areas isto initiate exploration to find profitable petroleumresources for future development and production.The most important environmental consequenceof exploration activities is the danger of acutedischarges of oil (oil spills), which are potentiallydangerous to larvae, fish eggs, fish, seabirds andmarine mammals, as well as life along the shore.

Before a new area is opened to activities, thoroughanalyses are carried out to see how harmful

exploration may be to the environment.The obligationto carry out such impact studies is laid out in thePetroleum Act.The studies are circulated for publiccomment and are then presented to Norway’snational assembly, the Storting. Special impactstudies have been carried out for the NorwegianSea, the Skagerrak and the southern Barents Sea.

Since the end of the 1980s a number of environ-mental and fishery-related studies have been under-taken concerning issues in the Barents Sea in generaland the areas north of Bjørnøya in particular. Hereproblems of oil and ice are particularly prominent.In view of the marketing outlook, the geologicaluncertainty and the foreseeable technologicaldevelopment concepts for this geographical area, aswell as its environmental vulnerability, there is greatuncertainty associated with the commercial interestin this area.Therefore the Ministry does not plan tocarry out new environmental and fishery studies of theBarents Sea North either this year or the next few years.

The Ministry will start the work of assessing theneed of and interest in petroleum activities incoastal area off Nordland (Mid-Norway) beyondthose locations that have already been opened up.The findings of this work will be closely evaluatedbefore possible new steps are taken. Before openingnew areas the Storting undertakes an overallevaluation of the environmental considerations,fishery interests, the interests of other affectedindustries and the benefits of extracting oil andgas.Areas where the drawbacks outweigh thebenefits are not opened to exploration activities.The Storting can also impose special conditions oncertain areas, such as no-drilling periods.


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The government also lays down specific require-ments in areas opened to exploration in order tolimit conflicts of interest between environmentaland fishing interests.Examples of such requirementscan be limitations on when drilling can take placeand specific emergency preparedness requirementsto limit the damage done by any oil spills.

Once an area is opened to exploration activities,blocks in the area can be advertised. Productionlicences are awarded to the companies which thegovernment, on the basis of an overall evaluation,believes can best realise the estimated assets inthe area.

There is general agreement on the need toimprove the current knowledge on the long-termeffects of discharges to sea.Studies have commencedon identifying the knowledge requirements andthus shed light on the need of research.

An overall review of ongoing work and existingstudies will be undertaken of the impact on theenvironment and fisheries of the offshore operationsin the North Sea.The purpose is to identify the needof any new studies of the overall consequencesof existing and future petroleum activity in theNorth Sea.

Development and operation phaseOnce commercially viable discoveries have beenlocated,the next phase is development and operationto realise the assets.

Before the participants in the production licencecan develop a discovery, the Petroleum Act requiresthat a plan for development and operation (PDO)and possibly a plan for construction and operation(PCO) is approved by the authorities.

As part of the PDO/PCO process, the developermust submit a study covering the impact on natureand the environment if the discovery in question

is realised.The study describes any environmentaleffect of expected emissions and discharges, anda systematic review of the costs and benefits ofpossible mitigating measures is undertaken. Boththe programme and the impact study itself arecirculated for comment among affected socialinterests. In addition new rules have been introducedon impact assessments relating to developmentsthat could cause environmental harm across theboundaries.

Depending on the scope of the development,the PDO/PCO is approved by the King in Council or the Norwegian Storting (national assembly)based on an overall evaluation of the project.Environmental protection is one of the criteria inthis evaluation.

In addition to the danger of acute discharges, theoperating phase entails continuous emissions anddischarges to air and sea.

These include:

• Discharge of water containing residual oil and chemicals

• Emissions of carbon dioxide (CO2) and nitrogen oxides (NOx) from energy production and flaring

• Emissions of non-methane volatile organic compounds (nmVOC) from fields based on buoy loading of oil

In order to limit the effects of emissions and dis-charges on the environment during the operatingphase, the authorities use the following policyinstruments:

CO2Under CO2 Tax Act, a CO2 tax must be paid forthe use of gas, oil and diesel in connection with


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petroleum activities on the continental shelf.Flaring gas beyond what is necessary for safetyreasons during normal operations is not permittedunder the Petroleum Act without the approval ofthe Ministry of Petroleum and Energy. However,in Storting White Paper no. 39 (1999–2000) it wasproposed to discontinue the rule of applying fora permit to flare and/or cold vent petroleum.The proposal was approved by the Storting.

NOxBeyond the PDO, NOx is currently not regulated onthe continental shelf during the operating phase.

nmVOCThe emission of nmVOC associated with loadingand storing of crude oil is now governed byemission permits under the Pollution Control Act.

Oil, organic compounds and chemicalsCompanies must apply to the Norwegian PollutionControl Authority (SFT) for permits to discharge oil,organic compounds and chemicals into the sea.The SFT issues permits in accordance with theprovisions of the Pollution Control Act. Under thePollution Control Act, the operating companieshave the responsibility and obligation of establishingthe necessary emergency preparedness to deal withacute pollution. Municipal and state emergencypreparedness plans provide further protection.

Closing phasePetroleum production on several fields on theNorwegian continental shelf has now ended or is in the process of ending.The authorities havemade decisions regarding the disposal of disusedinstallations on Nordøst-Frigg, Øst-Frigg, Odin, Mime,Tommeliten Gamma and Lille-Frigg.

The Ministry received in the autumn of 1999 a planfor the decommissioning of Ekofisk I.A Propositionon removing the installations in the Ekofisk areais expected to be submitted to the NorwegianStorting in 2001.

The provisions of the Petroleum Act regardingthe disposal of installations will be enforced incompliance with relevant national and inter-national obligations. In July 1998, the Commissionfor the Convention for the Protection of the MarineEnvironment of the North East Atlantic (OSPAR)passed a general prohibition against the disposal ofdisused offshore installations in the convention area.The prohibition makes exceptions for concreteinstallations, certain parts of large steel installationsand installations which for unforeseen circum-stances are more justifiably disposed of at sea.Before an installation is disposed under thisexception, consultations must be carried out withthe other parties to the convention.

The main rules otherwise are a consequence ofthe UN Convention on the Law of the Sea of 1982and guidelines adopted pursuant to it by theInternational Maritime Organization (IMO).Theserules mean that a major portion of the Norwegianinstallations which are not reusable will be broughtback to shore for recycling or disposal.

The OSPAR decision does not cover pipelinesand cables. In 1996 a three-year study programmeaimed at clarifying the effects of various disposalalternatives for pipelines and cables wascommenced.A Storting White Paper on this subjectwas submitted in 2000 based on this studyprogramme. In addition to a review of these studiesthe White Paper contained general principles forthe disposal of abandoned pipelines and cables,while also dealing with individual issues.


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The petroleum sector accounts for a substantialpercentage of Norwegian emissions of carbondioxide (CO2), nitrogen oxides (NOx) and non-methane volatile organic compounds (nmVOC).In addition, the sector generates minor emissionsof methane (CH4) and marginal emissions of sulphurdioxide (SO2). The data on emissions of CH4 andSO2 are, however, poor and many of the estimatesare highly uncertain. Operations also cause dis-charges of oil and various chemicals into the sea.

The various components of emissions contributeto different environmental problems, each of whichis international in nature. In dealing with trans-national pollution and emissions and dischargesin common areas such as international waters,it is necessary for the involved countries to worktogether to achieve desired environmental goals.

Global environmental problemsBoth CO2 and CH4 are greenhouse gases thatcontribute to the greenhouse effect.These areregulated internationally through the UNFCC.Norway’s obligation in accordance with the KyotoProtocol means that average emissions for the years2008-2012 may increase by 1% in relation to the1990 level.Compared to the current level, this meansa reduction of about 6%.This commitment can bemet through domestic reductions and partly in othercountries through the use of the Kyoto mechanisms.

Regional environmental problemsNOx, SO2 and nmVOC contribute to transboundaryregional environmental problems such as acid rain,overfertilization and ground-level ozone.They alsocause certain local pollution problems. Emissionsof these gases are regulated through protocolsunder the LRTAP Convention. In December 1999Norway, together with other European countries,USA and Canada, signed a new protocol (theGothenburg Protocol) which seeks to solve theenvironmental problems which acidification,eutrophication and ground-level ozone represent.Under the protocol Norway must reduce its emission

of NOx to 156 Kt by 2010, which represents a cutof 29% compared with the level of emissions in1990.For nmVOC the commitment is about identicalto the one Norway has accepted under the existingVOC Protocol. According to the latter the require-ment is that the emissions of nmVOC from all ofmainland Norway and the Norwegian economic zonesouth of the 62nd parallel are to be reduced by 30%by 1999 compared with the level in 1989. Norway has not met this obligation within the deadline.

Local environmental problemsregulated internationally

Oil and chemical discharge have local effects inthe immediate vicinity of the installations.The dis-charges are regulated internationally through theOSPAR Convention because they take place ininternational waters and are thus not the concernof only one country.

In accordance with the international agreementsmentioned above, Norway is obliged to limit itsemissions of the various substances. How this willaffect the petroleum sector will depend on theframing of the individual agreement. Emissionceilings are usually specified for each country inthe emission agreements.The framing of the agree-ments is decisive as to whether the obligatory emissionlimits must be carried out entirely within the bordersof each country, or whether the reductions can alsobe implemented in other countries where thereduction cost may be lower.The costs of reducingemissions and discharges from the various sources,and possibly in other countries as well, will bedecisive for to which degree measures will beimplemented vis-à-vis the petroleum sector.

For discharges to sea a maximum oil contentlevel has been set internationally for discharges ofwater. In other words, no ceiling has been specifiedfor total discharges, as is the case with air emissionagreements.The discharge of chemicals is governedinternationally by categorising the environmentalimpact of each chemical.

Status of emissions and discharges


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Figure 3 Sources of Norwegian emissions of CO2, 1999.(Source: Statistics Norway/Norwegian Pollution Control Authority)

Figure 4 CO2 emissions from oil and gas production broken downby source, 2000. (Source: MPE/Norwegian Petroleum Directorate)

Heating 20%

Other industrial processes 18%

Coastal traffic and fishing 10%

Road traffic 22%

Petroleum operations 24%

Other mobile sources 6%

Fuel gas 78%

Flaring 17%

Diesel 5%

Carbon dioxide CO2

Environmental effects of CO2

• The most important greenhouse gas contributingto the greenhouse effect, which in turn can leadto global warming

• According to the UN’s Climate Panel:"The balance of evidence suggests a discerniblehuman influence on global climate."

Human-generated emissions of CO2 are largelyconnected with the burning of fossil fuels. In anational context petroleum operations accountfor about 24% of the CO2 emissions (see Fig. 3),and this percentage is expected to increase withtime. Other major sources of emissions in Norwayare road traffic and other mobile sources, heatingand emissions from various industrial processes.

As Fig. 4 shows, CO2 emissions related to theproduction1 of oil and gas on the continental shelfmainly stem from the burning of gas in turbines andflares, and the burning of diesel on installations1.Of the fossil fuels, natural gas gives off the lowestCO2 emissions when burned. Beyond this, CO2emissions are connected with gas terminals onshore,exploration activities and indirectly to nmVOC

emissions from the loading of crude oil. Totalemissions of CO2 from the sector have grown yearby year, mainly as a result of increased activity.The trend in recent years and prognosis for theyears to come are shown in Fig. 5. Higher overallemissions do not mean that environmental improve-ments are absent. Improvements in energy utilisationand reductions in flaring have, however, not beengreat enough to outweigh the increase in energyuse that the greater activity has contributed to.One indication that activities have become moreefficient is that CO2 emissions per produced oilequivalent have been reduced by about 24% from1990 to 2000 (see Fig. 6).

The reduction per unit is inter alia attributed to:

• General improvements in technology

• Emission-reducing steps, inter alia becauseof the introduction of the CO2 tax in 1991

• Other factors, including changes in the productionpercentage of various fields and changes in thematurity of major fields

Emissions connected with producing a unit of oilor gas vary both between fields and over the life-time of the field.Reservoir conditions and transportdistance to the gas market mean that the need forenergy, and consequently emissions, varies amongthe fields.The variability of emissions over the lifeof the field is due inter alia to the rising percentage

1 The historical figures for the emission of CO2, NOx and nmVOC from offshore operations are preliminary.


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Figure 5 Total emissions of CO2 from the Norwegian petroleum sector. (Source: MPE/Norwegian Petroleum Directorate)

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Figure 6 Emissions of CO2 per produced unit.(Source: MPE/Norwegian Petroleum Directorate)

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of water in the well stream as fields age. Since it islargely the total quantity of liquid (water, oil andgas) that determines energy requirements in theprocessing plant, a field will have higher emissionsper produced unit as it ages.This is one of thereasons why we have seen a slight increase inemissions per unit in recent years. Figures from theNorwegian Petroleum Directorate in 2000 revealan increase in the overall emission of CO2 fromthe offshore sector from 1999 to 2000.

Future trends on the Norwegian continentalshelf in the direction of more mature fields andrelocation of activities northwards will consequentlycause emissions to increase per produced unit.Continued efficiency gains in power productionand more efficient energy use are necessary tolimit the expected increase in emissions.

The development of combined solutions forpower production offshore and reinjection of CO2from produced gas on Sleipner Vest are exampleswhich show that the Norwegian continental shelfis far ahead in terms of employing environmentallyefficient solutions.To avoid exceeding salesspecifications, it was necessary to reduce CO2content in the gas produced on this field.This isthe first time that CO2 removed from producednatural gas has been injected to subsea reservoirs.Thanks to this system annual emissions of about1 million tonnes of CO2 emissions are avoided.

In order to understand how high emissions of greenhouse gases from activities on theNorwegian continental shelf are in comparisonto similar operations in other countries, some

comparisons of emissions per produced unit ofoil and gas in various countries have been made.It must, however, be said that there are manyuncertainties regarding the reliability of suchcomparisons.

In a study done by SINTEF, greenhouse gaseson the Norwegian continental shelf were comparedto similar emissions in other countries includingRussia, the Netherlands, Britain and the US. Gasproduction-related CO2 emissions in Russia werenot available.

Activities on the Norwegian continental shelf didwell in the study.One example is that the productionof an oil or gas unit on the British continental shelf– which is perhaps the most comparable to activitieson the Norwegian continental shelf – generatesemissions that are more than three times higher thansimilar production on the Norwegian continental shelf.

Technology that will be implemented to reduce CO2 emissions:

• Removal of CO2 from the well streamand subsequent depositing on Sleipner Vest

• Utilisation of exhaust heat in the process system.

• More efficient energy production, e.g. combinedheat and power on Oseberg

• Optimal dimensioning of pipelines

• Replacement of old installations, e.g. Ekofisk

• Increased use of gas engines with higher efficiency than gas turbines

• Optimisation of new fields with respectto energy use and utilisation


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Figure 7 Sources of NOx emissions in Norway, 1999.(Source: Statistics Norway/Norwegian Pollution Control Authority)

Figure 8 NOx emissions from oil and gas production broken downby source, 2000. (Source: MPE/Norwegian Petroleum Directorate)

Heating 7%

Road traffic 24%


Other industrial processes 5%

Coastal traffic and fishing 40%

Other mobile sources 7%

Fuel gas 62% Flaring 19%

Diesel 19%

Nitrogen oxides NOx

Environmental effects of NOx

• Harm to fish and animal life throughthe acidification of river systems and soil

• Damage to buildings, stone and metalsas the result of acid rain

• Eutrophication resulting in changes in the composition of species in the ecosystem

• Damage to health, crops and building as the result of the formation of ground-level ozone when NOx and nmVOC are exposed to sunlight

NOx is formed mainly by burning fossil fuels. Thequantity of emissions depends on both combustiontechnology and how much fuel is burned. Forexample, combustion in gas turbines produces loweremissions of NOx than combustion in diesel engines.

Mobile sources account for the largest part ofNorwegian NOx emissions (see Fig. 7). Thepetroleum sector contributes 17%.As for CO2 gascombustion in turbines and flares together withdiesel consumption on the installations are majorsources of emissions in the sector (see Fig.8). Inaddition, there will also be some emissionsconnected with exploration operations and the gasterminals on land.As Fig. 9 shows, emissions of NOx from the sector

have grown steadily since 1990.The main reasonfor this is that the increased activity has meanthigher energy needs, thereby increasing emissions.The change in emissions per produced unit givesus an indication of the development in the efficiencyof operations on the continental shelf. Emissionsper produced unit are shown in Fig. 10.

Major reasons for the fact that NOx emissions havenot increased as much as the production of hydro-carbons are the same as for CO2:

• General technological progress

• Emission-reducing steps including improved efficiency in power supplies because of the introduction of the CO2 tax

• Other conditions such as changes in the production percentage of various fields and changes in the maturity of major fields.

The fact that there is a close connection betweenthe development of both CO2 and NOx is naturalsince the supply of power and flaring are mainsources of both emissions.

To gain an understanding of emissions on theNorwegian continental shelf compared to similaractivities in other countries, it is practical to comparevarious countries’ emissions per produced oilequivalent. It must be underlined that for a numberof reasons there is considerable uncertaintyconnected with such comparisons between countries.


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thou

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Figure 9 Emissions of NOx from Norwegian petroleum sector. (Source: MPE/Norwegian Petroleum Directorate)

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ced

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Figure 10 Emissions of NOx per produced unit.(Source: MPE/Norwegian Petroleum Directorate)

A study done for MILJØSOK indicates that emissionsof NOx on the Norwegian continental shelf arelower than in the countries with which it is naturalto compare ourselves.

Norway has signed a new international protocolgoverning i.a. the emission of NOx. Below possiblemeasures are outlined to reduce NOx emissions,but it is too early to say how this agreement willimpact on the petroleum sector.

Measures to reduce NOx emissions:• low NOx burners in new turbines.These have

the potential of reducing emissions from a gas turbine by almost 90%

• more efficient power generation

• optimisation of new installations with respect to energy consumption and energy production


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Figure 11 Sources of nmVOC emissions from the petroleum sector, 1999.(Source: Statistics Norway/Norwegian Pollution Control Authority)

Figure 12 Sources of emissions of nmVOC from the petroleum sector, 1999.(Source: MPE/Norwegian Petroleum Directorate)

Other industrial processes 19%Heating 4%

Road traffic 13%

Coastal traffic and fishing 1%Other mobile sources 4%


Diffuse emissions 3%

Terminal 7%

Fuel 1%

Buoy loading on the shelf 89%

Non-methane volatileorganic compounds (nmVOC)

Environmental effects of nmVOC

• The formation of ground-level ozone may damagea person’s health as well as crops and buildings

• It may cause respiratory injuries in the eventof direct exposure

• An indirect contribution to the greenhouse effect because CO2 and ozone are formed when nmVOCs react with air in the atmosphere

nmVOC is the term for volatile organic compoundsthat evaporate from crude oil and other substances.The various elements of nmVOC have differentimplications for the environment. It is, however,normal to view all gases as a whole whencomplying with international emissions obligations.

The petroleum sector is the main source ofemissions of nmVOC in Norway, accounting for59% of the national emissions. As Fig. 11 showsroad traffic and other industrial processes areother major sources of emissions. In the petroleumsector the bulk of the emissions stem from buoyloading of crude oil and from shore terminals.Some emissions also occur at gas terminals andduring minor leaks (see Fig. 12).

Until now emissions from buoy loading on the continental shelf have largely been connected withloading buoys on Statfjord and Gullfaks. Other bigfields like Oseberg and Ekofisk are based on thetransport of oil by pipelines to shore.There are bigdifferences in the emissions from loading one unitof oil on the various fields. One of the main reasonsis that the content of light gases in the oil variesbetween the various fields.

Several of the new developments on the continentalshelf are based on the use of floating storage ships.This type of development solution – in which theoil is stored under atmospheric conditions – maycause higher emissions of nmVOC than is the caseon fields where oil is stored in the base of theplatform (Statfjord and Gullfaks).This is becauseemissions will also occur during production inthe stores using such solutions.

For many years the oil companies have workedto make technology for recovering nmVOC availableto shuttle tankers, the ships that transport oil fromthe fields to the receiving ports.Two alternativesolutions are undergoing full-scale testing. Bothwill be able to reduce emissions from a loading byapprox. 70%. One of the concepts entails reinjectingnmVOC into the oil cargo and will expectedly bethe most likely candidate for older shuttle tankers.The second concept involves condensing and


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thou

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1990 1994 1998 2002 2006 2010 2014

Figure 13 Total emissions of nmVOC from the Norwegianpetroleum sector. (Source: MPE/Norwegian Petroleum Directorate)

kg

1,2

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0,4

1990 1992 1994 1996 1998 2000

Figure 14 nmVOC emissions per produced unit.(Source: MPE/Norwegian Petroleum Directorate)

using it as fuel to run the shuttle tankers.Thistechnology will probably be more workable fornew ships. Condensed nmVOC is a relatively cleanfuel, so that the emissions of environmentallyharmful gases from the operation of the shuttletankers will also be greatly reduced with thisalternative.

The prognosis for emissions of nmVOC from the sector shows a falling trend after the year 2001(see Fig. 13).This is due both to the fact that the oilproduction will reach peak levels in the course ofa few years,and that one expects recovery equipmentto be installed in keeping with demands set out inthe Pollution Act.

Sture is firstIn 1996 a nmVOC recovery plant was commissionedat the crude oil terminal on Sture.The plant hasthe potential to reduce nmVOC by about 90% perloading, and is the first of its type to be installedat a crude oil terminal.To use the plant, loadingships must be fitted with coupling equipment.Realised recovery in the first year of operation wasjust under 40% as only a limited number of thetankers were fitted with the necessary equipment.To promote the installation of coupling equipmenton the tankers, considerably lower port fees areoffered to ships that have installed such equipment.

International comparisons indicate that emissionsof nmVOC per produced quantity of oil and gas arehigher on the Norwegian continental shelf thanin other countries.The high percentage of buoyloading of oil on the Norwegian continental shelfcould be an explanation for why the emissionsare higher than in the other petroleum provincesthat were examined.

Measures to reduce nmVOC emissions:• Recovery of nmVOC on Sture

• Recovery of nmVOC on the continental shelf:- reinjection into the oil cargo- condensing for use as fuel on board

the shuttle tanker


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Environmental effects of oil discharges:

• Spills/acute discharges can harm fish,sea mammals, seabirds and shore zones

• There is considerable uncertainty about the environmental consequences of operational discharges.To this day no environmental damage has been proven and considerable research is taking place in the area, particularlyon the long-term effects.

Environmental effect of organic compounds

• There is great uncertainty on the long-term effects of dissolved organic compounds such asPAH compounds and alkyl phenols. Considerableresearch is being conducted in this area.

The environmental effects of chemicals:

• Discharges consist of a variety of substances with wide-ranging potential effects on the environment

• Most of the chemicals used (above 90%) are assumed to have little or no environmental effect

• Still little is known about the possible harmful effects of chemical discharges.

• Several of the chemicals are locally poisonous to a certain extent. Studies show that they are diluted in the water column so that they do notrepresent a major acute environmental hazard outside the immediate vicinity of the discharge

• A small portion of chemical discharges can haveextremely serious environmental consequences,including hormonal disturbances and bio-accumulation.

OilTotal discharges of oil from Norwegian petroleumoperations account for 2% of the total supply to theNorth Sea.The main supply of oil to the North Seacomes from shipping and the mainland via rivers.The oil discharges from the petroleum sector mainlystem from ordinary operations, although acutedischarges or spills occur.

Organic compoundsOrganic compounds are naturally present inreservoirs and are brought to the surface throughthe well with the produced water.The mostimportant compounds from an environmentpoint of view are and alkyl phenols.

ChemicalsChemicals is a generic term for all additives usedduring drilling operations and in the productionof oil and gas. It would be impossible to run efficientoil and gas operations without the use of chemicals.

Considerable efforts are therefore concentratedon developing chemicals that do the least possibleharm to the environment during use.To ensureprotection of the environment when the companiesselect chemicals, the CHARM model is used.

This model has been developed by the countriesparticipating in OSPAR. Some development workstill remains before the model is adequate as a toolin deciding choice of chemicals.

When looking at the environmental effects ofchemical discharges it is important to differentiatebetween:

• Discharges of largely harmless and more harmful chemicals

• The quantities that are used and discharged

• Where and under which conditions discharges are made, the conditions in the recipients.

More than 90% of the chemicals used in theNorwegian petroleum operations consist of chemicalsthat are thought to have little or no effect on theenvironment.A large proportion of these chemicalsare substances that exist naturally in seawater.Theremaining percentage include chemicals that havean effect on the environment or whose potentialeffect are not well enough documented.

In 1999 46% of the quantities used were dis-charged, including the water in which the chemicalswere dissolved.The figure for 1989 was 64%(excluding water).The chemicals not dischargedare dissolved in the oil, disposed of in the subsoilor treated as waste.

Oil, organic compounds and chemicals


22

Drilling As Fig. 15 shows drilling operations are clearlythe largest source of discharges of chemicals onthe continental shelf. Changes from year to yearin overall discharges of chemicals are thereforelargely caused by changes in the number of wellsdrilled (see Fig 16).

Since 1991 the discharge of oily cuttings hasbeen banned on the Norwegian continental shelf.As Fig. 17 shows the ban has helped to significantlyreduce oil discharges from operations in comparisonto what they would have been with continueddischarge of oily cuttings.

New drilling methods and new drilling technologyhave, together with increasing reinjection of cuttings,meant that discharges per metre drilled have gonedown in recent years, see Fig. 18. Since the use ofwater-based drilling fluids required greater use ofchemicals, the switch to this type of drilling fluidas a result of the prohibition on the discharge ofoil-based drilling mud has had the opposite effect.As previously mentioned, the oil containingdrilling mud accompanying cuttings is no longerdischarged on the Norwegian continental shelf.Recycling, subsea injection and disposal on landare alternative ways of avoiding drilling discharges.

Produced waterThe main source of oil released into the sea fromdaily operations is discharges of water that come up with the oil and gas from the well (producedwater), see Fig. 19. Although the water is carefully filtered before it is discharged, it still contains oil

residues and dissolved organic compounds. In1999 8,4% of all produced water was reinjected.

The average concentration of oil in producedwater on the continental shelf has been slowlydiminishing. Under the OSPAR Convention the oilcontent of water discharged into the ocean shouldnot exceed 40 g/m3 (milligrams per litre).The annualaverage for Norwegian installations in 1999 wasapprox. 25 g/m3 (milligrams per litre).This figureof concentration has been fairly stable since 1990(see Fig. 20).

Several of the largest fields are now so old thatmore water is now being produced per unit of oiland gas from the wells than before.This increasesthe volume of produced water which by itselfincreases discharges of oil. In recent years reinjectionof produced water has commenced on an increasingnumber of fields on the continental shelf.

Discharges of production and injection chemicalshave increased in recent years.This is mainlybecause of greater use of subsea templates andgreater quantities of water injection.These activitiesare normally dependent on using chemicals.The content of production chemicals in producedwater does not, however, show any clear trend(see Fig. 21).

Acute spills The damage to the natural environment becauseof oil spills depends more on the circumstances than the size of the spill.The spill site, time of year,wind strength, current and effectiveness of the

Figure 15 Chemical discharges on the continental shelf broken downby activity, 1999. (Source: Norwegian Pollution Control Authority)

Gas treatment chemicals 5.8%Production chemicals 4.4%

Pipeline chemicals 0.1%Other chemicals 0.8%

Drilling chemicals 88.9%


23

response to the emergency all play a vital role.Mostof the serious oil spills in Norway have involvedships near the coast.There have been no incidentsof major oil spills that have reached shore frompetroleum activities on the Norwegian continentalshelf. Expanded petroleum activitytowards coastal and more environ-mentally sensitive areas than earlierwill increase the risk of damage fromserious oil spills from activities onthe installations and oil tankersloading on these fields.

There have been relatively manyoil spills from installations on thecontinental shelf (see Fig. 22).Thetotal volume of oil discharged inconnection with oil spills is aspreviously mentioned neverthelessextremely limited in relation tothe supply from other sources.

Zero discharge strategy for discharges at sea

Zero discharge does not mean theend of all types of discharges and consequentlythe term can be somewhat misleading. Zerodischarges is a strategy that can be achieved witha continuous reduction of environmentallyharmful emissions towards a practical zero level,in which the damage to the environment dependson the content of potentially environmentallyharmful chemicals in addition to the time and

place of discharge.The degree of environmentaldamage depends on the discharge’s content ofenvironmentally harmful compounds, and thefield-specific discharge and recipient conditions.For the new independent developments the main

rule will be zero discharges to sea.A more detailed description will alsobe given of what the authorities meanby the term zero discharge. It isimportant that an overall evaluationof discharges to sea,emissions to airand energy conservation be donebefore the final technologicalsolutions are chosen.

The strategy will also be used for existing installations and fordeveloping smaller fields anddiscoveries in connection withexisting installations.Local conditionsat the various installations will affectwhich solutions will be practicalin such cases.

New technology is important in successfully implementing the

zero discharge strategy.Technology for separatingor blocking water before reaching the installationswill be major elements in realising this goal.Separation can take place either down in the wellor on the seabed. In addition to reducing dischargesto sea, such technology will also have favourableeffects on emissions to air and on oil production.

tonn

es200000

160000

120000

80000

40000

1990 1992 1994 1996 1998

Figure 16 Total discharges of chemicals from Norwegianpetroleum activities. (Source: MPE/Norwegian Petroleum Directorate)

Injection chemicals not measured before 1991.

tonn

es

3500

2500

1500

500

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Oily cuttings

Produced waterDisplacement

SpillTotal discharges

Figure 17 Total oil discharges broken down by source.(Source: Norwegian Pollution Control Authority/

Norwegian Petroleum Directorate)

Reinjection of cuttings

Oil reservoir

Bit

Cuttings mill

Finely groundcuttings

Denseformation


24

Troll: A PioneerThe Troll Pilot is a subsea separation unit made toseparate produced water from the rest of the wellflow in one of the production lines to the Troll Cplatform.The water is then to be reinjected into thereservoir. In this way both transportation ofproduced water to the platform is reduced as wellas the discharge of oily water.

Such benefits are achieved by down-holeseparation, which to date has only been tested infields located onshore.

Subsea reinjection of produced water is anothermethod that can contribute to a reduction indischarges where practical.The technology is usedtoday on several fields. However it is only at Ulathat this is done on a large scale - the other fieldshave smaller plants or test plants in operation.Reinjection of produced water will be implementedon several recently approved developments andwill be particularly interesting on fields anddiscoveries where there is a need for waterinjection to create pressure support.

Reinjecting produced water when there is noneed for pressure support increases energy useand emissions to air on the installations. In suchcases an overall evaluation will determinewhether the method is appropriate.

At other fields trials have been carried out toshut off water-bearing layers down in the well.However, such a step would also close off theproduction of hydrocarbons from these layers.

Technology for removing or reducingdischarges of produced water

• Whole or partial subterranean reinjection after separation on the installation.

• Mechanical or chemical shut-off of water-bearing layers in wells

• Separation in the well or on the seabed followed by reinjection

Technology for avoiding dischargesof drilling fluids

• Recycling

• Collection and subterranean injection

• Collection and disposal on land

Discharges to sea are further dealt with in theTopic section.


Figure 19 Oil discharges on the shelf broken down by activity, 1999.(Source: Norwegian Pollution Control Authority/Norwegian Petroleum Directorate)

Acute discharges 5%

Ballast and drainage water 10%

Produced water 85%

(g/m

3 )30

20

10

1990 1992 1994 1996 1998

Figure 20 Discharges of oil per cubic metre of producedwater. (Source: Norwegian Pollution Control Authority/

Norwegian Petroleum Directorate)

tonn

es

900

700

500

300

100

1990

30

25

20

15

10

num

ber Number

Tonnes

5

1992 1994 1996 1998

Figure 22 Acute oil spills.(Source: Norwegian Pollution Control Authority)

(g/m

3 )

200

160

120

80

40

1990 1992 1994 1996 1998

Figure 21 Production, injection and pipeline chemical contentin produced water. (Source: Norwegian Pollution Control Authority)

The amount of chemicals in 1998 includes water in which the chemicals are dissolved

tonn

es/m

etre

dril

led

0,45

0,35

0,25

0,15

1990

0,05

1992 1994 1996 1998

Figure 18 Discharges of drilling chemicals per metre drilled.(Source: MPE/Norwegian Petroleum Directorate)

25


Section 2

Discharge to sea


27

Most of the discharges in the next ten years willcome from fields currently producing hydrocarbons.These fields will gradually enter a more maturephase with an increasing production of water andconstantly growing production-related challenges.Without introducing new measures beyond thosecurrently adopted the discharge of produced water,oil and chemicals from the production process willincrease. The forecast for the period up to 2010shows that the amount of produced water will morethan double compared with today’s level. But dueto increased reinjection of produced water thedischarges to sea will only rise by about 50% (seeFigure 23). No major changes are expected in thedrilling activity the next few years, but the forecastsare uncertain and will of course depend on thefluctuation in the oil price.

Consequently discharges to sea, not least thoseassociated with produced water, represent aconsiderable challenge for the petroleum industryin the coming years.This is why we have chosen tofocus on it in our Topic section in Environment2001.The Topic section details both the challengesfacing the offshore industry in this area as well asthe measures that could contribute to solving theproblem.Attention is especially paid to the role newtechnology could play with regard to this issue.

To put a sharper focus on this problem we havedecided to concentrate on continuous dischargesof environmentally-harmful substances orcomponents associated with drilling and welloperations as well as the production process.This means that certain discharges will only be

dealt with to a minor degree,such as acute dischargeof oil and those discharges linked to the finaldisposal of installations.

DISCHARGE COMPONENTS

The three most important continuous dischargesto sea from offshore operations are oil, organiccompounds and chemicals.

As far as oil is concerned the Norwegian offshoresector accounts for approx.2% of the overall dischargeof oil to the North Sea.The main contributors arethe rivers and shipping.The main source offshoreof continuous oil discharges is drops of oil inproduced water (dispersed oil). In addition thereis dispersed oil in ballast water and drainage water1

as well as from acute oil spills (see figure 24). Inour account here of the continuous discharge ofoil we will for the most part focus on dispersedoil in produced water.

Organic compounds are components that arenaturally present in the reservoir and brought upwith the produced water.The most important compounds which are potentially the most harmfulare PAH compounds and alkyl phenols.

Chemicals is a common term for all the additivesand other substances that are used in drilling andproduction operations related to oil and gas.Theseare employed amongst other things to ensureregular and safe operations on the installations.

1 Ballast water comes from the storage cells for crude oil. Drainage water is water from hosing down deck areas where oily water as well as rain water can be expected.

mill

Sm

3

300

250

200

150

100

Discharge of produced water

Produced water

50

2029202320172011200519991993

Figure 23 Forecast of the discharge of produced water.(Source: Norwegian Petroleum Directorate)


28

The chemicals used in drilling and well operationsaccount for most of the discharge of chemicals,although some chemicals are also used in theproduction process.

In addition to the three discharge componentsmentioned here offshore operations also accountfor some other discharges to sea.These are amongstothers non-organic compounds contained inproduced water, such as heavy metal (arsenic,nickel,copper, lead) and low-specific activity scale foundin the formations.These compounds will only bedealt with below to a minor degree.This is mainlybecause they are either not very harmful to theenvironment or that the discharges are very small.

DISCHARGE SOURCES

The most important continuous discharges to seafrom offshore operations are from two sources,drilling/well operations and produced water.

Drilling and well operationsThe chemicals added to the drilling fluid duringdrilling operations are the biggest source ofchemical discharges on the Norwegian continentalshelf. In order to drill exploration and productionwells it is necessary to use drilling fluid.This fluidis amongst other things used to grease the drillstring and transport drill cuttings out of the well,as well as for pressure control and stabilising thewell.The drilling fluid is made up of differentchemicals and additives; it can be based on oil orwater or a synthetic oily fluid. In relation to thenumber of metres drilled the consumption of

these three types of fluid was respectively 45, 45and 10%.

Water-based drilling fluids are normally usedwhen drilling the top sections of a well.The drillcuttings containing this fluid are discharged directlyto sea.Water-based drilling fluid is cheaper thanthe other two fluids, but does not have the samegood technical qualities. A number of chemicalsmust be added in order to employ water-baseddrilling fluid.Work is now in progress both inindividual companies and across the field ofplayers to find a standardised water-based drillingfluid to enhance the possibility of reuse.Thepossibility of reusing it on the installations isdependent on the storage capacity on site.Shippingit to shore and reuse involves transporting a lotof drilling fluid, but generally speaking reuse isbeneficial both for the external environment,working environment and economy. By reusingthe drilling fluid the total quantity of such fluidcan be reduced over time by up to 30%.The environ-mental qualities of water-based fluids are betterthan oil-based and synthetic fluids.

Oil-based drilling fluids are relatively speakinglow cost and have the best drilling-technical qualities.They are therefore commonly used in the lowestand most complicated sections of a well. Since1991 there has been a ban on discharging drillingfluids based on oil.The oily drill cuttings musttherefore either be reinjected or transported toshore for treatment and disposal.

Synthetic drilling fluids have similar qualities tothose based on oil.They were developed to havefluid that was less toxic and more biodegradable than

disc

harg

e of

oil

(tonn

es)

4000

1999

Drilling3000

2000

1000

Production

Ballast water

19961993199019871984

Figure 24 Development of operational oil discharges from 1984-1999.(source: Norwegian Pollution Control Authority 2000)


29

oil-based fluids. However they are more expensivethan oil-based fluids and may not be discharged tosea.The Norwegian Pollution Control Authority may,however, grant a permit to discharge drill cuttingscontaining synthetic oil.The synthetically basedfluids have better environmental qualities thanoil-based fluids.

From 1998 to 1999 there was an increase in thedischarge of drilling waste (drilling fluid andcuttings) of 11%.This was largely due to increasedactivities. Still, when seen in relation to the numberof metres drilled, there has been a positive trendin recent years.A total of 355 000 tonnes of drillingwaste was discharged in 1999, of which 322 000tonnes came from drilling with water-based fluidswhile synthetic drilling fluids accounted for 33 000tonnes.The discharge of synthetic drilling fluiddecreased from 3 291 tonnes in 1998 to 1 294 tonnesin 1999.According to data from the NorwegianOil Industry Association’s report "Discharges fromthe Norwegian offshore industry 1999" a total of108 000 tonnes of drill cuttings and drilling fluidfrom oil-based operations was produced in 1999,of which 72% was reinjected.The remaining wasshipped to shore to an approved facility.

Produced waterAn oil reservoir will always have formation water.When the reservoir is emptied of oil, the wellsproduce more water.The produced water alwayscontains crude oil in a dispersed form, as well asa number of other organic compounds and solubleinorganic compounds from the formation.Theproduced water furthermore contains chemicalsthat are used during drilling, production andinjection. Despite treating the produced waterbefore it is discharged it will still contain oil residue.It also contains dissolved organic compoundsand residual chemical additives.

Produced water accounts for about 84% of thedischarge of oil from the offshore industry. In 1999almost 99 million tonnes of produced water wasdischarged,compared with close to 91 million tonnesin 1998.This resulted in 2 467 tonnes of oil beingdischarged with the produced water in 1999compared with 2 111 tonnes in 1998 (NorwegianPollution Control Authority 1999).

NATIONAL POLICY

National goals• Discharge of oil from operations shall not lead

to unacceptable harm to people’s health or theenvironment.The risk of harming the environmentand other disadvantages caused by acute pollution shall be at an acceptable level.

• Discharge of certain environmentally toxic substances is to be stopped or reduced considerably in the next few years.

• Discharge and use of chemicals representing a serious threat to people’s health and to the environment are to be continuously reduced so as to have ended such discharges within a generation (2020).

In Storting White Paper no. 58 (1996-1997) "Environ-mental policy for sustainable development" theGovernment furthermore stipulated that a require-ment of zero discharge to sea was to be introducedby 2005.The goal of zero discharges can be achievedby a continuous reduction of environmentally-harmful discharges down to a practical zero level,where the environmental damage depends onthe contents of potentially harmful chemicals inaddition to the time and place of the discharge.The Government’s goal is not to permit environ-mentally-harmful discharges from new fields basedon a stand-alone concept.Existing fields will further-more be reviewed with a view to implementingdischarge-reducing measures by 2005.

MeansThe Petroleum Act and the Pollution Act are theauthorities’ most important means to reduce dis-charges to sea, and are used in all phases of thepetroleum operations from exploration to fieldabandonment.Before an area is opened up to allowoil activities the authorities conduct comprehensiveregional environmental impact assessments.Through this process the authorities can shieldareas that are especially vulnerable either bybanning exploration or have a requirement ofdrilling-free periods.When awarding new areasthe authorities may require e.g. that there bedrilling restrictions, restrictions on seismic surveysor contingency plans to combat acute pollution.Before a discovery can be developed the PetroleumAct requires that a plan for development andoperation (PDO) be approved by the authorities,in which i.a. the environmental aspects of a field


development are dealt with. In order to dischargeany oil or chemicals to sea the companies mustapply for a discharge permit from the NorwegianPollution Control Authority. One of the demandslaid down in the discharge permit is the regularmonitoring of the marine environment. Regulationsare currently being prepared which will set outgeneral conditions pertaining to discharges fromplanned operations.These regulations will replaceindividual conditions granted under the PollutionAct.The authorities audit the companies accordingto Norwegian legislation and internal companyrequirements.

INTERNATIONAL AGREEMENTS

The London Convention -72 is a global agreementgoverning the dumping of waste and other materialsas well as the burning of waste at sea. Since 1993the burning of environmentally harmful waste hasbeen banned.

The OSPAR Convention is an environmental agree-ment based on international law for the protectionof the marine environment in the North-East AtlanticOcean.The parties to the convention develop andfollow up their cooperation by participation in theOSPAR Commission.This is where definite measuresand programmes are adopted amongst others tocombat discharges from the onshore and offshoreindustry. A total of 15 countries with a coastlineor rivers to the North-East Atlantic are members.The convention came into force in March 1998,replacing the Oslo and Paris Conventions.TheOSPAR Convention deals with the discharge anddumping at sea.The principle purpose of OSPARis to prevent and eliminate pollution and protect

the marine environment against the harmfuleffects of human activities.

The OSPAR Convention:

• has stipulated that water discharged to sea mayonly contain a maximum of 40 mg of oil per litreof water;

• binds the countries to govern their use and discharge of environmentally-harmful chemicals;

• has placed a limit of 1% of oil content in drillingwaste during exploration and production;

• has introduced guidelines for the carrying out of regular surveys of the environment around installations;

• has adopted rules for the disposal of abandonedinstallations;

• has adopted an offshore strategy which is now being followed up.

The North Sea Conference was first held inBremen, Germany, in 1984.The main purpose of theconference was to reach political agreement onnecessary measures to protect the marine environ-ment of the North Sea.This also includes politicalinitiatives to ensure an efficient implementationof existing agreements.

The fourth North Sea Conference was held inEsbjerg, Denmark, in 1995.This conference agreedon a long-term goal of eliminating the discharge ofenvironmentally-toxic substances within a generation.Agreement was also reached on further developingand utilising environmentally-friendly technologyto protect the marine environment.The fifth North SeaConference will take place in Norway in March 2002.

30


ASSESSING ENVIRONMENTAL IMPACT

What do we know?The discharge of drill cuttings and drilling fluidscover the seabed and thus alters the chemicaland physical conditions on the seabed.Furthermorethe mounds of drilling waste, which in some casescan be several metres high, lead to a change in theseabed fauna.The effect on the seabed fauna,causedby water-based drilling fluids, is mainly limited toa 500-metre area from the installation. In connectionwith older fields, where oil-based fluids have beenused,the impact can be seen from 2 to 2.5 kilometresfrom the installation. Solutions range from leavingthe mounds of cuttings, covering them or removingthem.Work is in progress to find the best solution.The British oil companies, through UKOOA, havestarted a common research programme (1999-2002)to study the cutting deposits.The Norwegian OilIndustry Association participates in this work,while at the same time mapping the scope of thedrilling deposits on the seabed off Norway.

The discharge of chemicals from offshoreoperations contains a large number of substanceswith a greatly varying effect on the environment.The chemicals that are environmentally acceptableconstitute an increasing share of the discharges.Some chemicals have a certain acute toxic effect.But studies show that these chemicals very quicklybecome diluted in the water column and do notrepresent a serious threat to the environment beyondthe immediate vicinity of the discharge. Althoughpractically all the chemicals discharged on theNorwegian continental shelf consist of substancesthat are assumed to pose a minor threat to theenvironment, there is uncertainty as to the unknownlong-term impact of some of the chemicals.

31

Environmental impact of oil discharges

• Spills/acute discharge can harm fish, mammals,sea birds and the coastal zone.

• There is uncertainty as to the environmental consequences of operational spills. No environ-mental damage has been proven to date.

Environmental impact of organic components

• There is uncertainty on the long-term effects of decomposing organic components such as PAH compounds and alkyl phenols.This is subject to considerable research.

Environmental impact of chemicals

• The discharges consist of a long series of substances whose potential effect on the environment varies greatly.

• The majority of the chemicals used (90%)are believed to have little or no environmentalimpact.

• Still only little is known about any long-term effects of discharged chemicals.

• Several of the chemicals have a certain local toxic impact. Surveys show that they are dilutedin the water column and so do not lead to anymajor acute environmental impact beyond theimmediate vicinity of the discharge.

• A small portion of the chemicals discharged mayhave very serious effects on the environment,including hormone disorders and they can be bioaccumulating.


Produced water contains soluble components (PAHcompounds and alkyl phenols) which may have apotential for long-term negative effects.Thesecomponents have a reduced biodegradability andhave in certain instances proven to be accumulatingand have impacted negatively on the reproductionability of marine organisms.

The oil companies have for many years fundedresearch into the long-term effects of discharges tosea. Still the general view persists that there is aneed to have more knowledge about this issue. Inorder to get the most out of the overall research effort(both public and industry-based) the NorwegianMinistry of Petroleum and Energy has taken aninitiative for a better coordination of this work.

What do we need to know more about?The lack of knowledge about the long-term effectsof produced water and discharge of chemicals isone of the major gaps in our knowledge on theenvironmental impact of the current activities.This applies especially to the ecological impactof the discharges and the effect of particularlyvulnerable resources and ecological key species.More knowledge is also needed concerning thedevelopment of a tool for environmental riskanalyses.There is furthermore a need of moreresearch associated with effect of discharges onthe deep-water ecosystems and Arctic ecosystems.The fate of drilling chemicals after being dischargedto sea is partly unknown. Some will adsorb toparticles and sink to the bottom while others willbecome dissolved in or transported with the water

column or be taken up by feeding organisms.Consequently there is a need to test the impactof the chemicals on marine life. Marine species arecurrently being tested to determine acute toxicity(OECD/OSPAR), but there is also a need of long-term testing (over a 20-30 day period) to be ableto determine possible chronic effects.

Petroleum operations will increasingly be carriedout in environmentally sensitive areas, where thereare important spawning and fishing grounds. Inthese areas there will be strict demands as to theknowledge about the spreading, impact of smallconcentrations, long-term effects and bio-accumulation of discharges as well as knowledgeabout emergency preparedness.

Special deep-water challengesBefore 1997 Norway’s deepest offshore well was523 metres water depth,while current wells exceed1 300 metres.Eight wells have been drilled in the deep-water areas on the Norwegian shelf.To date boththe planning and execution of all the drillingoperations in deep water have been successful.Still we have limited knowledge about the spreadingand effect of discharges in deep water.Several kindsof plankton,e.g. red feed,stay in the deep-water areasin the winter months and these species play a crucialrole in the marine nutrition chain. Acute spillsfrom wells in deep water will behave differentlyfrom such spills in shallow areas. Deep-water spillswill be spread over larger areas and will be furtherdispersed into the water column before reachingthe surface.This may lead to special requirements

32

???

100

80

60

40

20

Chemicalson the A and B list

1997

Other chemicals+ balance

Chemicalsto be phased

out

Chemicalswith a discharge

ban

1998

1999

70,7

86,5890,34

26,24

11,348,21

2,64 2,05 1,44 0,11 0,03 0,02

Figure 25 Total discharge of chemicals according to per cent in weight in 1999 compared with 1998 and 1997 per environmental category. (source: Norwegian Oil Industry Association 2000)


33

relating to contingency plans and oil-recoveryequipment.The oil spill contingency plans shouldbe judged on a case-by-case basis.

The Norwegian Deepwater Program (NDP) wasstarted in 1996 by the operators of the deep-waterlicences. Considerable resources have been usedto study the patterns of currents and spreadingof hydrocarbons in the event of an uncontrolleddischarges in deep water.

Especially vulnerable areasIn recent years the offshore operations have movednorthwards and closer to the coast.This meansthat the oil activities will increasingly be conductedin environmentally-sensitive areas.The coastal

population have for generations harvested from thecoastal resources, not least by fishing and gathering.In the environmentally-sensitive northern areas thenutrition chains are shorter and fewer. Oil andchemicals dissolve more slowly and plants andanimals contain considerably more fat.This makesit easier to accumulate many of the most problematicenvironmentally-toxic substances.The legislationand practical measures relating to exploration foroil and gas will take into account that the traditionalindustries are to be able to harvest the resourcesof the sea also in the future.The wording of theannouncements of the last five licensing rounds,from the 15th round (1996) to the North Sea round2000, requests companies to take particularly intoaccount the fishing activities and the presence ofliving marine resources during the planning of thedrilling activity.

ENVIRONMENTAL MANAGEMENT

The chemicals currently being discharged arebecoming more and more environmentally-friendly.This is due to the authorities’ ban on the

use of chemicals known to be harmful to theenvironment and active environmental managementrequirements.The improvements have come aboutamongst other things by the introduction of frame-work discharge permits, environmental testingrequirements for chemicals, requirements onsubstitutes and the operator’s follow up of thephasing out of potentially harmful chemical sub-stances.The chemicals on the Norwegian PollutionControl Authority’s A and B2 list (environmentallyacceptable) increasingly make up a larger portionof the discharges (see figure 25).

Tools have been designed to ensure that theenvironmental improvements are achieved in themost efficient manner. CHARM (Chemical Hazard

and Risk Model) is a method used to rank theenvironmental impact of chemicals.By using CHARMthe industry can compare the different chemicalsand choose the ones that have the least harmfuleffects.The authorities have also imposed on theplayers to carry out environmental risk assessments(by means of CHARM) of new chemicals beingemployed. A method called EIF (EnvironmentalImpact Factor) has also been developed whichmakes it possible, on the basis of knowledge aboutdischarged quantities, spreading and toxicity, todetermine which components in produced waterthat are most harmful to the environment.TheDREAM project (Dose-Related Risk and EffectAssessment Model) is another tool designed to limitthe risk of harming the environment from thedischarge of produced water.This latter is basedon EU guidelines for environmental risk assessment.

To date both the planning and execution

of all the drilling operations in deep water

have been successful.

2 The chemicals are commonly divided into four classes (lists):1.List A (PLONOR) are chemicals assumed to have a minor or no

negative effect on the environment2.List B contains chemicals that may have a temporary effect on

the marine environment, but which are well documented.3.Chemicals to be phased out.4.Chemicals which have a discharge ban.


TECHNOLOGICAL SOLUTIONS

Drilling and well operationsTechnological developments in recent years havecontributed to improved mapping of reservoirs,which in turn has resulted in fewer dry holes.Thishas led to a considerable reduction in dischargedquantities.

New drilling technology. In recent years the rapiddevelopment of drilling technology has led to majorefficiency gains. By employing this new technologyit is possible to drill very long and deviated wells,horizontal wells and wells which curve and bend.All of these come under the expanded term ofdirectional drilling.The development of multilateraldrilling will further reduce the need of wells byhaving more branch wells down in the reservoir,which share the upper part of the well.Thecombination of long, horizontal and multilateralwells has several environmental advantages.Thereduction in the number of wells reduces theproduction of cuttings and drilling fluids, whileat the same time reducing the use of chemicals.Another beneficial side-effect is reduced energyconsumption.Larger areas can now be reached fromone installation and reduce the pollution associatedwith development and operations (see figure 26).

Reinjection of oil-based drilling waste has nowbecome a standard operational procedure on most

fixed installations. In 1999 a total of 72% of the oil-based drilling waste was reinjected.The cuttings areground up and diluted before being injected backto a formation by means of the mud injection pump.

Reuse of drilling fluids. Some companies haveroutines for re-circulation and regeneration ofused drilling mud. Suppliers of drilling mud arecontinually working to improve such routines.Environmentally-friendly drilling fluids with goodtechnical qualities are also increasingly beingdeveloped.

Alternative weight substances. During a drillingoperation it is necessary to add a weight substance,usually barytes.This additive contains heavy metalwhich is not desirable for environmental reasons.Ilmenite is an alternative weight substance thatcontains less heavy metal and which is used onseveral installations in the Norwegian sector.Ilmenite opens up new areas of application fordrill cuttings. Instead of depositing cuttings asspecial waste onshore, it can be used to coverpipelines, in the cement and ceramics industry, asa filler in asphalt and rubber and to surface cycleand walking paths.

35

Figure 26 Technological developments withindrilling and well operations. (Source: Statoil)


36

Produced waterSteps to reduce the environmental damage causedby the discharge of produced water can be dividedinto four technological areas (see figure 27):

• Reduction of water production

• Reinjection of produced water

• Treatment of the produced water before discharging it to sea

• Reduced discharge of environmentally-harmful chemicals.

Figure 27 illustrates different methods to reducethe production of water (water shut-off, downholeseparation and sidetracking), as well as reinjectionafter separation on the platform and on the seabed.

Reducing water production. The best way ofreducing discharges associated with produced wateris to reduce the production of water.The shapeand location of wells may affect how long it takes

before the field begins to produce water and howmuch water that is produced.

Water shut-off down in the wells is used to reducethe production of water and thus the dischargeof produced water. Mechanical methods are mostcommon to day. Chemical shut-off methods are lessused amongst other things because they require

special reservoir conditions to be successful and because problems of durability sometimes occur.Over the years new equipment and methods haveprovided a flexible and selective way of shutting-off of water-producing zones, which do not requirethe use of a drilling installation.The trend is towardsequipment that can be remotely controlled fromthe surface.

Water

Oil

Oil

Oily water reinjection

Hydrocycloneseparator

Water pumpOilpump

Electriccable

Figure 27 Technological solutions for the treatment of produced water. (source: Statoil)

Separation on the platform anddischarge to sea

Separation on the platform and reinjection to reservoirs

Separation on the seabedwith reinjection to thesubsurface

Selectivewater shut-off.

Downhole separationand reinjection

Sidetracking to zones with a higher fraction of oil


37

Downhole separation. By using downholeseparation the produced water is separated down inthe well and reinjected.The main aim of downholeseparation is to avoid handling large quantitiesof water on the installation by moving the processdown into the production well.This also preventsthe capacity of the processing system becominga problem when the water production increases.This can help prolong a field’s lifetime and soenhance the oil production. At the same time theuse of chemicals is reduced because of improvedseparation conditions and by avoiding dischargesthrough water reinjection.This process removesalmost all of the water from the production flow.

Reinjection of produced water. The reinjection ofproduced water is an important option because itcan do away with the discharge of oil and chemicalsfrom produced water. However, this option isdependent on the specific reservoir conditions andit can therefore not be applied everywhere. If thedecision is made early in the planning phase of anew field to reinject the produced water, then theextra costs of reinjection will be much lower thanif it is implemented at a later stage. A decision toreinject produced water to provide pressure supportand boost production may only marginally increasethe investment costs of a new installation and causeno or a very limited increase in the emission to air.If the produced water for some reason cannot beused as pressure support and a separate injectionwell must be drilled this would mean considerableextra investments and an increase in the emissionto air. On existing installations it may be possibleto convert to reinjection without major outlays, ifconditions allow it. In the Norwegian sector morethan ten fields reinject produced water or haveplans to do so, and this option is being consideredat several other fields. It is expected that the amountof produced water that is reinjected will increase inthe coming years.

Seabed separation. Seabed separation involvesseparating the produced water from the well flow atthe seabed, so that only oil and gas are transported

up to the production installation.This method willreduce the amount of water requiring treatmenton the installation.The separated water is for themost part reinjected. Discharges at the seabedwould only result in minor discharges of chemicalsbecause of the reduced need of corrosion andhydrate inhibitors on the surface. In order that thistechnology is to become a real environmentalalternative to downhole separation, the water mustbe reinjected and possibly provide pressure supportat those fields where this is possible.

Treatment of produced water before dischargeto sea. Treating or cleaning produced water isprimarily done by removing the oil before the wateris discharged to sea. Oil recovered in this way isfed back to the oil treatment facilities and soldtogether with ordinary crude.The removal of othersubstances, such as heavy metals, aromatic sub-stances and phenols, may lead to end products thatmust be handled and deposited in an environ-mentally-safe manner.

The treatment of produced water on installationsis done by means of physical facilities such asflotation tanks, separators, hydrocylones andcentrifuges. Depending on the process chosenthere will always be oil residues in the water.Thedischarge requirement of oil in the water is 40 mgper litre.The oil content in produced water variesconsiderably from field to field, but on averagethe concentration of oil in recent years has beenstable around 22-25 mg per litre. But there is a risein the total amount of oil discharged because ofa higher production and discharge of water.

Different measures are being introduced to makethe treatment process better, simpler and cheaper,while at the same time reducing the chemicalrequirements.To considerably enhance the effect ofthe treatment of oil and other components, severaltreatment stages utilising different technologieswhich operate in a series, may have to be built.There are a number of methods for furthercleaning the produced water, but some of theserequire plants that are too cumbersome orcomplicated for use offshore. Some methods are


38

being tested offshore, while others are beinglooked into to a varying degree. Among the mostrelevant treatment technologies for use offshoreNorway are:

• Methods for making small drops of oil melt together into bigger drops so that the oil can more easily be separated from the water in the separation process.Varieties of this has been tested at the Draugen field and used at Troll.

• A method where the oil components are capturedby the condensate, which is mixed with the produced water.This technology has been tested at the Statfjord field.

• Methods consisting of different types of filters which can remove oil and other components from the water.This technology has been testedat the Oseberg field.

Some of the treatment methods can also removeother organic components, particles, chemical residue and heavy metal from the produced water.

CHALLENGES

It is a challenge to reduce environmentally-harmfuldischarges to sea without this leading to a higherenergy consumption and increased emissions to air.It is necessary to undertake an overall evaluation

of the different measures, while at the same timetaking into account conditions specific to thedifferent fields.Good knowledge about the reservoirand hydrocarbon flow may make it possible to placewells in a manner that contributes to reducing theproduction of water.Process optimisation is anotheroption requiring integration of know-how fromdifferent skills and operating environments.Several different technological options exist at themoment. But as several of these technologies havenot been tested and undergone qualification, itremains a challenge to decide which methodshould be selected for a particular field. In thiscontext cooperation and sharing lessons learntcould be very important in finding solutions basedon cost/utility considerations.On many installationsseveral smaller measures have been introducedwhich collectively can contribute considerably todischarge reductions. It could be very useful toshare this knowledge and the lessons learnt.

For further information view the Internet pages of:Norwegian Pollution Control Authority:http://www.sft.noNorwegian Oil Industry Association:http://www.olf.no (Including the MILJØSOK-reports)OSPAR: http://www.ospar.org


F A S E T T

P O Box 8148 Dep, N-0033 Oslo Tel +47 22 24 90 90, fax +47 22 24 95 65

http://www.oed.dep.noE-mail: [email protected]

Y-0101/3 E


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