Environment Report 2014
ENVIRONMENT REPORT 2014 OIL & GAS UK
ENVIRONMENT REPORT 2014
ENVIRONMENT REPORT 2014
Contents
1. 2. 3.
Foreword
5 7 9 9 9
Executive Summary
Emissions and Discharges Offshore 3.1 Introduction 3.2 Produced Water 3.3 Chemical Discharges 3.4 Discharge of Drill Cuttings 3.5 Atmospheric Emissions
13 17 20 25 30 30 31 41 42 42 42 43 47 47 49 51 53 54 55
3.6 Waste
4.
Accidental Oil and Chemical Releases
4.1 Introduction 4.2 Trend Data
4.3 Industry Initiatives Well Flow Survey 5.1. Introduction 5.2. Survey Design 5.3. Survey Results
5.
6.
Significant Issues and Activities 6.1 Provision of Evidence
6.2 Collaborative Work
6.3 Additional Services to Members
7.
Forums and Technical Groups 7.1 The Environment Forum 7.2 Oil Spill Response Forum
7.3
Decommissioning Forum and Decommissioning Sub-Committee
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8.
Glossary
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ENVIRONMENT REPORT 2014
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1. Foreword Welcome to Oil & Gas UK’s Environment Report 2014 . This year’s report presents data to show the overall environmental performance of the UK offshore oil and gas industry through the key metrics of emissions to the atmosphere, discharges to the sea, waste disposal and accidental releases. Data up to the end of 2013 are included (the latest full dataset), both a detailed analysis and a decadal trend analysis are provided and the key findings are given in the executive summary. In last year’s Environment Report we presented the results of an analysis of platform production wells on the UK Continental Shelf (UKCS) to determine how many are capable of natural flow and hence have the potential to spill oil. In this report we complete the picture by presenting an analysis of the subsea production well inventory. Of the 10,875 wells in the combined database, 992 platform wells and 543 subsea wells are capable of natural flow and 111 of these can flow at a rate greater than 5,000 barrels of oil per day. This analysis will be used to ensure that the oil spill response capability on the UKCS is appropriate and will help to determine the requirements for financial responsibility in the event of an incident. Throughout 2013/2014, the regulatory and management controls being applied to the marine environment continued to increase, for example, through the establishment of further Marine Protected Areas, Marine Plans and implementation of the Marine Strategy Framework Directive and European Offshore Safety Directive. The work undertaken by the Environment Directorate in support of these activities is detailed in Chapter 6, as is information on the significant studies undertaken to improve our knowledge of the marine environment. We hope you find the Oil & Gas UK Environment Report 2014 both informative and useful. To help improve and add value to next year’s report we welcome comments and questions from all stakeholders. Please address these to Mick Borwell, environment director, on mborwell@oilandgasuk.co.uk.
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Mick Borwell Environment Director, Oil &Gas UK
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ENVIRONMENT REPORT 2014
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2. Executive Summary
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Industry Emissions and Discharges • The regulator, the Department of Energy & Climate Change (DECC), issues permits for discharges and emissions from offshore installations on the UK Continental Shelf (UKCS). The potential effects of any such discharge on the marine environment must be considered as part of the permit application. • Discharges and emissions are closely monitored offshore and are recorded in the Environmental Emissions Monitoring System (EEMS) database. Analysis of the data from 2000 to 2013 indicates that the volumes of produced water discharged and atmospheric emissions continue to decline. This is the result of careful management and application of the best available techniques by industry. • Volumes of drilling chemicals discharged to the marine environment increased by 35 per cent from 2012 to 2013 due to exploration of new areas and the development of new and existing fields. The wells drilled commonly includedmultiple sidetracks, increasing the overall length of wells drilled and the quantity of chemicals discharged in 2013. The OSPAR Commission 1 considers the large majority (over 90 per cent) of these chemicals to pose little or no risk to the environment. • Research studies that have been carried out on the UK and Norwegian Continental Shelves over the past ten years indicate that contaminants from offshore operations are at background levels beyond the immediate vicinity of the platform. Although contaminants can be detected in individuals of some species, no effects have been detected at a population or community scale. • In 2013, almost 198,000 tonnes of waste materials were returned to shore from UK offshore oil and gas operations. The proportion of waste sent to landfill has been declining steadily over the past decade as a result of increased reuse and recycling and alternative treatments such as waste to energy.
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• In 2013, 28 per cent (41,000 tonnes) of total operational waste (147,000 tonnes) was reused or recycled, including scrap metal, oils and sludge.
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Accidental Releases • The UK oil and gas industry does its utmost to prevent accidental oil and chemical releases by investing heavily in the provision of physical barriers, such as downhole safety valves, maintenance to minimise leaks, as well as in the development of handling procedures and training to influence human behaviours. In the event of an accidental release, operators have approved emergency response plans in place and use a wide range of response techniques to monitor, contain and recover releases.
• Analysis of the Petroleum Operations Notice 1 data over the past decade, which is submitted by operators to DECC, shows that the volume of accidental releases continues to decline.
• In 2013, accidental oil releases represented three per cent of the total oil discharged (permitted and accidental) to the environment and 0.0002 per cent of total oil production. Over 40 per cent of these releases were less than 0.001 tonnes (or one kilogramme) and would rapidly disperse in the marine environment.
1 The OSPAR Commission aims to protect and conserve the North East Atlantic and its resources. See www.ospar.org
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ENVIRONMENT REPORT 2014
• Accidental chemical releases in 2013 represented 0.1 per cent of the total chemicals (permitted and accidental) discharged to the marine environment. Many of these chemicals are hydraulic fluids from subsea systems and flow lines. Hydraulic fluid is largely water-based, has a low hazard potential and, as such, has no significant impact on the marine environment. Well Flow Survey • In 2013, Oil & Gas UK surveyed operators to collate data on 5,121 platform wells, representing the total platform well inventory on the UKCS. Nineteen per cent (992) of these wells are capable of unassisted flow of hydrocarbons to the surface. Only 21 of these, however, are able to flow at greater than 5,000 barrels of oil per day (bopd). • In 2014, additional information was collected by Oil & Gas UK on 5,754 subsea wells on the UKCS. Nine per cent (543) of these wells are capable of unassisted flow to the surface, of which only 90 are able to flow at greater than 5,000 bopd.
• The interim results indicate that only one per cent of all platform and subsea wells in the Oil & Gas UK inventory are capable of flow rates above 5,000 bopd (111 wells out of a total 10,875 wells).
Oil & Gas UK • Oil & Gas UK’s Environment Directorate continues to support members in three key areas in 2014, through the provision of evidence to government, policy makers and North Sea stakeholders; by improving our understanding of the marine environment through collaborative studies; and by providing datasets and resources to members, which help in their everyday environment management activities.
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3. Emissions and Discharges Offshore 3.1 Introduction
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In 2013, 524 million barrels of oil equivalent (boe) were produced on the UK Continental Shelf (UKCS), satisfying about 50 per cent of the UK’s oil and gas demand 2 . As with all processes to generate fuel and energy, hydrocarbon exploration and production and subsequent facility decommissioning result in discharges and emissions to the environment. These discharges and emissions include atmospheric emissions, produced water, drill cuttings, chemical discharges, waste and accidental releases. In the UK, European and national legislation tightly control discharges and emissions offshore, through a permitting process. To comply with these requirements, operators must consider the potential effect of the discharge or emission on the environment as part of their permit application, which is reviewed and approved by the Department of Energy & Climate Change (DECC) as the regulator. The industry closely monitors discharges and emissions and submits data to be recorded in the Environmental Emissions Monitoring System (EEMS) database. Oil & Gas UK has supported the EEMS database since 1992 and DECC uses it to help meet its national reporting requirements to Europe and the OSPAR Commission 3 . This chapter analyses the aggregated EEMS data from operators for the period 2000 to 2013 for atmospheric emissions, produced water, chemical discharges and waste. The EEMS data was extracted in June 2014 and, this year, Oil & Gas UK has carried out additional analysis on the 2013 data and sought clarification from individual operators on specific data entries where necessary. This supports our ongoing objective to enhance EEMS data quality. 3.2 Produced Water Produced water is water that comes to the surface with hydrocarbons during production. This can be water naturally trapped in the subsurface reservoir or water injected into the reservoir to help lift oil to the surface. Produced water is separated from oil and gas in the first stages of processing and then treated and discharged to the sea. It forms the largest permitted discharge and is the greatest volume of fluid handled offshore. Operators obtain approval for produced water discharge through an oil discharge permit under the Offshore Petroleum Activities (Oil Pollution Prevention and Control) Regulations 2005, which must be applied for using the DECC UK Oil Portal 4 .
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2 See DECC’s DUKES 2014 Statistics www.gov.uk/government/statistics/digest-of-united-kingdom-energy-statistics-2014-internet-content-only 3 The OSPAR Commission aims to protect and conserve the North East Atlantic and its resources. See www.ospar.org 4 The UK Oil Portal allows operators to apply for and receive consents and permits. See https://itportal.decc.gov.uk/eng/fox/live/PORTAL_LOGIN/login
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ENVIRONMENT REPORT 2014
3.2.1 Produced Water Volumes The UKCS is a mature basin and production has been falling since the early 2000s. As reservoirs deplete, oil and gas extraction requires greater energy input and management of larger volumes of produced water. Indeed, in 2013, produced water accounted for 71 per cent of the total well stream fluids. Nonetheless, for the past decade, the volumes of produced water discharged to sea have been declining, from a peak of 273 million m 3 in 2002 to 150 million m 3 in 2013. This is the result of careful management of produced water, application of the best available techniques and reinjection of produced water.
Figure 1: Discharge and Reinjection of Produced Water from 2000 to 2013
Produced Water Discharged
Produced Water Reinjected
350
300
250
150 Million m 3 200
100
50
0
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Source: EEMS June 2014
From 2001, the volumes of produced water reinjected into the reservoir for oil recovery or disposal has increased. Over the past five years, reinjection volumes have stabilised at around one fifth of the total volume. In 2013, 40 million m 3 of produced water, representing 21 per cent of the total produced water (190 million m 3 ), was reinjected.
However, reinjection is not always technically feasible on installations, nor may the reservoir be suitable. Reinjection also consumes additional energy and therefore may not always be the best environmental option.
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The volume of produced water that is discharged to sea from offshore installations varies over the year, correlating with the variations in production. In 2013, produced water volumes declined between July and September, coinciding with the offshore summer maintenance period.
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Figure 2: Monthly Discharge and Reinjection of Produced Water in 2013
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Total Water Volume
Volume of Water Reinjected
Production 2013
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12
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4 Water Million m 3 6 8
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2
1
Production Million Tonnes
0
0
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Source: EEMS June 2014, DECC, Oil & Gas UK
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3.2.2 Produced Water Composition – Oil Content Produced water mainly comprises water but it does contain small amounts of other naturally occurring substances from the reservoir, such as dispersed oil, dissolved organic compounds, naturally occurring radioactive material (NORM) and traces of chemicals added during production. Any components commonly discharged in produced water rapidly dilute at sea. The chemical composition is determined by the reservoir geology and may also change during the reservoir’s production life. In 2013, the volume of oil discharged with produced water was 2,176 tonnes or 0.001 per cent of the total volume of produced water.
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ENVIRONMENT REPORT 2014
Produced water is sampled daily offshore for hydrocarbon concentrations and the results are recorded in the EEMS database. On the UKCS, hydrocarbon concentration levels have been declining since 2000. OSPAR recommendation 2001/1 requires that individual installations do not exceed an oil-in-water concentration of 30 milligrammes per litre (mg/l). In 2013, the average concentration on the UKCS was half this at 14.35mg/l, measured using the GC-FID method 5 , and is lower than the average over the year in 2012. The OSPAR Quality Status Report (QSR) 2010 6 stated that the oil discharges in produced water have fallen on average by 20 per cent from 2000 to 2006 in the OSPAR area through investment in separation technologies as well as reinjection projects. There was a small variation in the average monthly concentrations of oil-in-water discharged in 2013 from 12.90 to 16.68 mg/l. No correlation was found between hydrocarbon concentration in produced water and levels of production or summer maintenance activity.
Figure 3: Oil Discharged with Produced Water from 2000 to 2013
Oil Discharged with Produced Water
Average Oil Content with IR Method
Average Oil Content with GC-FID Method
Oil in Water Concentration Limit
7,000
35
6,000
30
5,000
25
4,000
20
3,000
15
Tonnes
2,000
10
Milligrammes per Litre
1,000
5
0
0
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Source: EEMS June 2014
5 Up to 2006, oil concentration in produced water was measured using the infrared method (IR). The IR method measures with solvent both the dispersed and dissolved hydrocarbons extracted. The method can, however, include other organic chemicals, giving an artificially high result and can also underestimate dissolved hydrocarbons. To rectify this and to provide a more accurate analysis of hydrocarbon content, OSPAR agreed (Agreement 2005-15) the use of a new method for oil-in-water analyses, based upon a modified version of the ISO 9377-2 (GC-FID) method. 6 The OSPAR Commission’s Quality Status Report 2010 is available to download at http://qsr2010.ospar.org/en/index.html
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3.2.3 Potential Environmental Impacts of Produced Water It is possible to measure concentrations of hydrocarbons in marine sediments. Analysis from Marine Scotland Science in 2010 7 found that poly-aromatic hydrocarbon concentrations in offshore and coastal sediments around the UK are close to background concentrations. Monitoring from Oil & Gas UK from 2006 to 2009 on random sediment samples also indicated that hydrocarbon concentrations are at background levels. This indicates that discharge of hydrocarbons from offshore installations is not resulting in increased concentrations within seabed sediments beyond the immediate vicinity of the installation. Discharge volumes of produced water and concentrations of hydrocarbons from the UKCS are comparable with those from the Norwegian Continental Shelf (NCS) 8 . In 2013, a ten-year study (PROOF and PROOFNY projects 9 ) was completed in Norway on the effects on the marine environment of oil and gas operational discharges. The study investigated areas such as biomarker, endocrine and reproductive effects on certain individuals of species, such as haddock, cod and mussels, that live in close proximity to produced water outlets. The evidence gathered suggests that the effects of produced water discharges are local, in general confined to within one to two kilometres of the outlet, and that the risk of widespread impact is low. Whilst effects could be detected in individuals, no effects were found on the population or community scale. 3.3 Chemical Discharges Chemicals are used offshore in the exploration and production of hydrocarbons. The chemicals can be divided into three categories according to their application. 1. Drilling Chemicals Drilling fluids (‘mud’) are used to lubricate the drill bit and drilling assembly and facilitate the removal of rock fragments during the drilling of wells. They also help to control pressure in the well. The largest component is water but the fluids may also contain organic phase fluids, weighting agents and acidity control chemicals, and they are generally recycled and only discharged when permitted. 2. Production Chemicals Specialist chemicals are used to produce oil and gas to maintain equipment integrity and optimise production. These chemicals include demulsifers to improve separation of oil from water; corrosion inhibitors to protect equipment; scale inhibitors to slow down the build-up of scale in pipework; and valves and biocides to reduce marine growth on equipment. Maintaining equipment integrity is critically important for the safety of offshore workers and to protect the environment. Industry discharges the residues of used chemicals under permit to the marine environment with the produced water. Cement and cement additives are also used in the drilling of wells and occasionally discharged with prior approval from DECC.
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7 Scotland’s Marine Atlas is available to download at www.scotland.gov.uk/Publications/2011/03/16182005/0 8 A report on the Norwegian petroleum sector is available to download at http://npd.no/Global/Engelsk/3-Publications/ Facts/Facts2013/FACTS_2013.pdf 9 More information on the project group PROOFNY can be found at http://bit.ly/PROOFNY
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ENVIRONMENT REPORT 2014
3. Pipeline Chemicals Chemicals are used to maintain pipelines and ensure pipeline integrity. These include biocides and oxygen scavengers. Discharge of all the above is tightly controlled in the UK under the Offshore Chemical Regulations 2002 (as amended 2011). These discharges are permitted and approved by DECC prior to any discharge, following submission by operators of drilling operations, production operations and pipeline operations applications using the UK Oil Portal. These applications contain a description of the chemicals to be used and discharged, a risk assessment of the impact of any discharges, and any proposed monitoring and/or techniques that will be applied to minimise discharges. 3.3.1 Chemical Discharge Volumes In 2013, almost 131,150 tonnes of chemicals were discharged to sea, of which 79 per cent (103,000 tonnes) were from drilling activities. The total volume of chemicals discharged has varied each year since 2000; this is primarily due to changes in the levels of drilling chemicals discharged.
Figure 4: Chemical Discharges by Activity on the UK Continental Shelf from 2000 to 2013
180,000
Drilling Chemicals
Production Chemicals
Pipeline Chemicals
160,000
140,000
120,000
100,000
80,000
Tonnes
60,000
40,000
20,000
0
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Source: EEMS June 2014
In general, the volume of drilling chemicals discharged coincides with the levels of exploration, appraisal and development well drilling on the UKCS. Between 2000 and 2010, a period averaging around 93,000 tonnes of drilling chemical discharge per year, an average of over 250 wells per year were drilled on the UKCS. Drilling activity in the UK then dropped; 165 and 175 wells were drilled in 2011 and 2012, respectively. This correlates strongly to the drilling chemical discharges shown in Figure 4 as they also fell to around 67,000 tonnes per year in the same period.
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However, in 2013, the volume of drilling chemicals discharged increased by 35 per cent from 2012, while the total number of wells drilled remained relatively low at 164. Analysis of the top ten largest drilling discharges in 2013 showed that they are associated with multiple, rather than single, wells at the same site (a main well plus at least two sidetracks), increasing the overall length of wells drilled and hence the amount of chemicals used offshore. The majority of drilling discharges in 2013 are associated with mobile drilling units that were deployed to drill exploration and production wells in new and existing fields west of Shetland, in the southern North Sea and for subsea tiebacks in the central North Sea (CNS). Meanwhile, nine per cent of drilling fluids discharged came from existing fixed production platforms to develop current fields and for maintenance of well integrity. Small volumes were also discharged during well plug and abandonment (P&A) activities in the CNS and northern North Sea areas. Over the next decade, the proportion of drilling fluid discharges coming from well P&A may increase as activity in this area is forecast to rise. Over 900 wells are forecast to be decommissioned in this period 10 . 3.3.2 Chemical Discharge Composition On the UKCS, only chemicals that have been registered with the Centre for Environment Fisheries and Aquaculture Science’s (CEFAS) Offshore Chemical Notification Scheme (OCNS) are permitted. The OCNS applies the OSPAR Harmonised Mandatory Control Scheme (HMCS), developed through OSPAR Decision 2000/2 (as amended by OSPAR Decision 2005/1) and its supporting recommendations. The OSPAR HMCS contains a list of chemicals considered by OSPAR to pose little or no risk to the environment (PLONOR list). The OCNS involves generating an environmental dataset on toxicity, persistence and bioaccumulation potential using pre-screening criteria and a decision-support tool called CHARM (Chemical Hazard Assessment and Risk Management). Operators must consider the CEFAS OCNS classification as part of their risk assessment on the discharge of any chemicals as well as the European REACH (Registration, Evaluation, Authorisation and restriction of Chemicals) Enforcement Regulations 2008, which impose obligations on manufacturers/importers of substances and downstream users to evaluate and control the risks associated with their use.
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10 Oil & Gas UK’s Decommissioning Insight 2014 is available to download at www.oilandgasuk.co.uk/knowledgecentre/market_information.cfm
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ENVIRONMENT REPORT 2014
In 2013, over 90 per cent of the drilling chemicals and over 90 per cent of the pipeline chemicals discharged by the UK offshore oil and gas industry were on the PLONOR list. The top ten drilling chemical discharges by volume were all PLONOR substances and the majority of discharges were brine. Through the HMCS, some chemicals used offshore are assigned a ‘SUB’ or ‘substitution warning’, which means a reliable value cannot be calculated to indicate whether the chemical might bioaccumulate. In 2013, only five per cent of all chemical discharges contained a ‘substitution warning’ and operators are encouraged to select alternative products. In some cases, however, there may be justified technical reasons from the supplier as to why a particular substance cannot be immediately substituted. Efforts to replace ‘SUB’ chemicals have resulted in a 90 per cent reduction in such discharges since 2003 11 .
Figure 5: Composition of Chemical Discharges from the UK Continental Shelf in 2013*
140,000
120,000
100,000
Pipeline Other Pipeline SUB
Pipeline PLONOR Production Other Production SUB Production PLONOR Drilling Other Drilling SUB Drilling PLONOR
80,000
60,000
Tonnes
40,000
20,000
0
Source: EEMS June 2014
2013
* ‘Pipeline, Production and Drilling Other‘ refers to chemicals used and discharged offshore not classified as PLONOR and without a substitution warning.
11 The OSPAR Quality Status Report 2010 is available to download at http://qsr2010.ospar.org/en/index.html
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3.3.3 Potential Environmental Impacts Chemicals discharged from offshore operations are immediately diluted into the sea. The level of dilution depends on the water depth and currents. The dilution is at least 1,000 times at a distance of 500 metres from the discharge point, reducing the discharge to levels that are not acutely toxic to marine organisms. 3.4 Discharge of Drill Cuttings Drill cuttings are rock fragments generated during subsurface well drilling offshore. To prevent the well becoming clogged, the cuttings are carried back to the surface in the drilling fluid known as ‘mud’ due to its colour and consistency. There are two main forms of drilling fluids: water-based and non-aqueous-based (synthetic or oil). It is common practice to use both when drilling various sections of the same well. Water-based fluids are generally applied in the upper sections while non-aqueous fluids are used in the more technically demanding sections. The choice and composition of the drilling fluid depends on reservoir characteristics and consideration of the safety and environmental risks. On the drilling rig, the cuttings are separated from the fluids and disposed of, while the drilling fluid is recycled. The disposal option selected depends on the type of drilling fluids used. Cuttings are either thermally treated onboard to reduce the oil content and then discharged to sea, returned to shore for treatment and disposal, or injected back into a suitable rock strata.
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Since 2001, following OSPAR decision 2000/3, cuttings contaminated with non-aqueous drilling fluids cannot be discharged to sea without treatment to reduce the oil content to below one per cent of the total volume.
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Prior to any discharge, operators must conduct a risk assessment to investigate the potential environmental effects as part of their permit application to DECC.
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ENVIRONMENT REPORT 2014
3.4.1 Volumes of Cuttings Discharged The majority of cuttings discharged to sea from the UKCS are generated by drilling activities that use water-based drilling fluids. These fluids are labelled gold or silver under the CEFAS OCNS scheme, considered to have the lowest hazard to the marine environment. In 2013, 54,000 tonnes of cuttings separated from water-based fluids were discharged to sea. Meanwhile, 5,000 tonnes of cuttings from non-aqueous drilling fluids were discharged to sea after they had been treated to remove any residual oil to less than one per cent of the total volume. As mentioned, a permit must be sought from DECC before any such discharges.
The bulk of non-aqueous fluid cuttings (more than 40,000 tonnes) were brought to shore (see section 3.6) and 11,000 tonnes were injected back into the rock strata.
Figure 6: Drill Cuttings Discharges on the UK Continental Shelf from 2010 to 2013
70,000
Non-Aqueous Fluids
Water-Based Fluids
60,000
50,000
40,000
30,000
Tonnes
20,000
10,000
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2010
2011
2012
2013
Source: EEMS June 2014
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3.4.2 Composition of Discharged Cuttings Drill cuttings vary in size and texture, ranging from fine sand to gravel, depending on the type of rock being drilled and the type of drill being used. Drill cuttings may contain residuals of the drilling fluid used and are disposed of accordingly as previously outlined. 3.4.3 Potential Environmental Impacts The Oil and Gas Industry Marine Monitoring and Assessment Committee commissioned (through Oil & Gas UK) a series of wide-area monitoring studies between 2005 and 2009. The work used a wide-area stratified random sampling strategy in the Fladen ground, east Shetland basin, east Irish Sea and CNS. Each of the four surveys involved collecting over 100 sediment samples that were analysed for grain size, carbonates, organic matter, metals and radio-chemicals. The samples revealed that all contaminants were at background levels and that far-field contaminants from offshore activities, including drilling operations and their associated drill cuttings, were not detectable. From 2005 to 2006, surveys were also undertaken around five producing platforms on the UKCS to investigate long-term trends in contaminant persistence and biological recovery. Following the cessation of oil-based mud discharges in 2001, the surveys confirmed significant reduction over time of sediment hydrocarbon concentrations and a return to background or near background levels. This year, Oil & Gas UK commissioned Heriot-Watt University to undertake a spatial and temporal assessment of North Sea benthic species using the UK Benthos database. A statistical framework was developed to test the far-field effects of drilling operations, accounting for the physical factors relevant to benthic distribution such as water depth. Nineteen platforms were considered, 90 per cent of which did not reveal far-field effects on the benthic data. The spatial extent of the impact footprint was greatest within the first one to two years after drilling, but with time the footprint shrank, in some cases to about 50 metres.
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The statistical framework was also able to detect environmental effects and signs of recovery within the benthic dataset; the benthos’ capacity for recovery was notable.
The PROOFNY study on the NCS (see section 3.2.3) also found that the effect on benthic organisms fromdrill cuttings contaminated with water-based muds was confined to a distance of 100 to 500 metres from the installation.
Overall, recent studies indicate that chemicals and cuttings discharges fromoffshore installations are not increasing contaminate concentration within seabed sediments beyond the installation’s immediate vicinity. Over time, the area of impact of cuttings shrinks to the immediate vicinity of the installation and the benthic organisms are able to recover.
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3.5 Atmospheric Emissions Extraction, stabilisation and export of hydrocarbons involve several processes that give rise to atmospheric emissions. These include combustion to provide electrical power and to drive compressors and pumps; flaring of excess gas for safety and during well testing; and incidental releases from tank loading, as well as firefighting and refrigeration equipment.
Combustion and flaring result in emissions of carbon dioxide (CO 2
), carbon monoxide (CO), methane (CH 4
) and
oxides of nitrogen (NO x
) and sulphur (SO x
). Small amounts of nitrous oxide (N 2
O) are also released. Releases of
volatile organic compounds (VOCs) and CH 4
may occur during tank loading, while firefighting and refrigeration
equipment may release halon and chlorofluorocarbons (CFCs).
There are several legislative instruments that apply to and control emissions from the offshore industry, including the European Union Emissions Trading Scheme (EU ETS), the Carbon Reduction Commitment (CRC), the Regulation (EC) 1005/2009 on substances that deplete the ozone, the Prevention and Control of Pollution (PPC) Regulations (as amended 2007), the Energy Savings Opportunity Scheme (ESOS) Regulations 2014, and the EU Energy Efficiency Directive. DECC issues permits for atmospheric emissions and these emissions are recorded by the operator in the EEMS database. 3.5.1 Atmospheric Emissions Trends emissions offshore since the early 2000s (see Figure 7 opposite). This correlates with the decline in production and volumes of produced water over the same period. Production is forecast to level out over the next five years which could result in a plateauing of offshore emissions. In 2012, CO 2 emissions from UK offshore oil and gas production contributed three per cent of the total domestic CO 2 emissions 12 . There has been a sustained decrease in CO 2 , NO x , CO and SO 2
12 This data came from DECC. See http://bit.ly/CO2factsheet. Values for 2013 were not available at the time of writing.
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Figure 7: Offshore Emissions of Carbon Dioxide, Nitrogen Oxides, Carbon Monoxide and Sulphur Dioxide from the UK Continental Shelf from 2000 to 2013
1
NOᵪ Emissions SO₂ Emissions
CO Emissions CO₂ Emissions
2
80,000
10 12 14 16 18 20
70,000
3
60,000
50,000
4
40,000
0 2 4 6 8
Tonnes
30,000
5
20,000
CO 2 Emissions Million Tonnes
10,000
0
6
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Source: EEMS June 2014
7
2013
CO
NO
CO
SO
2
x
2
8
Tonnes
14,310,000
45,000
21,000
3,400
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ENVIRONMENT REPORT 2014
In 2013, 45,600 tonnes of CH 4 follow the trend in declining emissions.
and 38,000 tonnes of VOCs were emitted from offshore installations. These values
Figure 8: Offshore Emissions of Methane and Volatile Organic Compounds on the UK Continental Shelf from 2000 to 2013
CH₄ Emissions
VOC Emissions
0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 90,000
Tonnes
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Source: EEMS June 2014
Methane is the principal component of natural gas although VOCs are also found in natural gas. These gases are released through incomplete combustion and venting during loading and offloading of crude oil from tankers. Emissions of VOCs offshore have halved since 1999 13 as a result of action taken by operators to reduce gas escape and the use of vapour recovery systems, where practical, at offloading facilities.
13 As reported in the OSPAR Quality Status Report 2010 , which is available to download at http://qsr2010.ospar.org/en/index.html
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3.5.2 Sources of Atmospheric Emissions Oil & Gas UK, with support from industry, has worked with DECC, the Environment Agency and the Scottish Environment Protection Agency this year to introduce and co-ordinate new emissions auditing requirements as part of ESOS under the Energy Efficiency Directive. The effects of the scheme will be monitored and reported in future editions of this report. are mainly generated offshore during the burning of fuel for energy. Carbon dioxide emission sources for 2013 are shown in Figure 9, with the majority generated by fixed installations. Last year, 77 per cent of CO 2 emitted was from burning gas, diesel or oil for fuel to generate heat and light for the installation, to process and export hydrocarbons, and to treat and reinject produced water. emissions is from the combustion of fuel gas; 3.4 million tonnes of gas was used for this purpose in 2013. Volumes of fuel gas used have been decreasing since 2008 (see Figure 10 overleaf), in line with decreasing production, associated gas and produced water volumes. Emissions of CO 2 , NO x , CO and SO 2 The largest single source of offshore CO 2
1
2
3
4
5
Figure 9: Sources of Carbon Dioxide Emissions Offshore on the UK Continental Shelf in 2013
1%
3%
1%
6
Gas Flaring and Venting (Fixed)
12%
22%
7
Gas Consumption (Fuel) (Fixed)
Diesel Consumption (Fuel) (Fixed)
8
Oil Consumption (Fuel) (Fixed)
Gas Flaring and Venting (Mobile)
Diesel Consumption (Fuel) (Mobile)
61%
Source: EEMS June 2014
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ENVIRONMENT REPORT 2014
In 2013, 1.2 million tonnes of gas was flared on the UKCS and the volume has remained consistent over the past five years. Flaring is necessary offshore for maintenance, well testing and, most crucially, for the safety of offshore workers. Gas venting and flaring are both subject to consent under the Petroleum Act 1998, which aims to conserve gas by avoiding unnecessary wastage during hydrocarbon production.
Figure 10: Comparison of Offshore Fuel Gas Used and Gas Flared on the UK Continental Shelf from 2008 to 2013
6
Flare Gas Fuel Gas
5
4
3
2
Million Tonnes
1
0
2008
2009
2010
2011
2012
2013
Source: EEMS June 2014
Despite declining production, it is difficult to reduce emissions as hydrocarbon extraction from mature reservoirs necessitates the use of more energy intensive techniques, such as the reinjection of produced water. Furthermore, as some equipment ages (for example turbines), their efficiencies can drop. The steady decline in emissions witnessed over the past decade can therefore be attributed to reduced fuel gas use as well as the implementation of energy efficiency measures, continued maintenance, and optimisation of equipment and processes.
Low NO x turbines can be effective in reducing NO x experienced offshore leading to increased downtime 14 .
emissions, however, operational difficulties have been
14 More detail can be found in the Oil & Gas UK Technical Note on Offshore Gas Turbines and Dry Low NO x
Burners at
www.oilandgasuk.co.uk/publications
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3.5.3 Potential Environmental Impacts
1
Atmospheric emissions have several potential environmental impacts:
2
• Contributing to anthropogenic global warming – which is attributable to greenhouse gas emissions, notably CO 2 and CH 4 • Stratospheric ozone depletion – caused by halon and CFCs, which are known collectively as ozone depleting substances (ODS) • Ground level ozone formation – caused by reactions between VOCs and NO x • Acidification – caused by emissions of acid gases such as NO x and SO x Emissions fromoffshore oil and gas production, however, only form a small proportion of the UK’s total greenhouse gas emissions (less than three per cent in 2012). Although ODS have the potential to have a global impact, they are used in closed systems offshore. Furthermore, the prospect of ozone formation and acidification is minimised by the geographical location of most offshore installations. 3.6 Waste The offshore oil and gas industry generates a number of waste streams during exploration and production activities. Waste is stored on the installation and returned to shore for recycling and disposal. These waste materials include: • Cuttings (rock fragments) from drilling wells • General inert wastes, such as segregated recyclables (paper, glass, cardboard, aluminium cans), food waste, scrap metal, non-hazardous paints and chemicals • Special wastes, such as oils, hazardous chemicals and drums/containers containing hazardous residues, batteries and electrical equipment • Other wastes such as asbestos, explosives and clinical wastes The volume of waste generated varies according to the level and type of maintenance, drilling and production activities taking place offshore. Scrap metal is generated during shutdown, construction and/or refurbishment, while plastic and metal drums are employed to supply and use chemicals offshore. Special wastes arise from drilling, workover and platform maintenance activities. Operators have a duty of care to manage and monitor all wastes generated offshore and their subsequent handling and disposal through an environmental management system. These volumes are recorded in the EEMS database annually.
3
4
5
6
7
8
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ENVIRONMENT REPORT 2014
3.6.1 Waste Volumes In 2013, almost 198,000 tonnes of materials were returned to shore with the single largest category being special wastes at 39 per cent (77,000 tonnes) of the total. Between 2004 and 2010, the amount of waste being brought onshore each year was relatively stable at 130,000 tonnes. Over the past three years, however, volumes have been increasing, especially for general wastes.
Figure 11: Waste Generated Offshore by Type on the UK Continental Shelf from 2001 to 2013
250,000
Cuttings
Special
General
Other
*
200,000
150,000
100,000
Tonnes
50,000
0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
*'Other' category includes wastes such as asbestos, explosives and clinical wastes. This is brought onshore in very small amounts and appears on the above graph in purple
Source: EEMS June 2014
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The largest category of operational waste generated in 2013 comprised sludges, liquids and tank washings. These can be inert or contain traces of hazardous substances and are separated and labelled as such offshore.
1
Sludge disposal involves separating and treating oil, water and solids onshore. The cleaned solids are then sent for disposal to landfill while the separated water is treated to enable discharge to the sewer. Recovered oil is usually reused as a fuel after further treatment. Last year, small volumes of waste were returned onshore from decommissioning activities, the majority of which were segregated recyclables and 30 per cent was scrap metal that was recycled. Decommissioning projects on the UKCS have been achieving recycling rates in excess of 95 per cent in recent years.
2
3
Figure 12: Waste Generated Offshore by Activity on the UK Continental Shelf in 2013
4
0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 90,000 100,000
Total Disposed Operational
Total Disposed Decommissioning
5
6
Tonnes
7
8
Source: EEMS June 2014
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ENVIRONMENT REPORT 2014
3.6.2 Waste Disposal Routes Last year, decommissioning wastes were mainly returned to yards/ports in Teeside, in north east England, and Lerwick on the Shetland Islands. Nearly 80 per cent of operational wastes, meanwhile, were returned onshore in Aberdeen, with over 80 per cent of drill cuttings sent to the north east of Scotland ports of Aberdeen and Peterhead. Figure 13 illustrates the waste disposal routes for operational wastes. The proportion sent to landfill has been declining steadily over the decade since 2001 as a result of increased reuse and recycling and alternatives such as waste to energy. In 2013, 28 per cent (41,000 tonnes) of of total operational waste (147,000 tonnes) was reused or recycled, including scrap metal, oils and sludge.
Figure 13: Disposal Routes of Operational Wastes from the UK Continental Shelf from 2001 to 2013
Landfill
Reuse and Recycle Other *
Incineration Waste to Energy
160,000
140,000
120,000
100,000
80,000
60,000
Tonnes
40,000
20,000
0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
*Other: Any other disposal route, includes composting, land spreading and treatment of aqueous wastes
Source: EEMS June 2014
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Drill cuttings returned to shore (or back-loaded cuttings) may contain residues of drilling fluids and are usually sent to specialist treatment plants in the north east of Scotland, where solids are recovered and oil and water are separated. In 2013, the recovered solids accounted for 56 per cent of back-loaded cuttings, with the majority sent to landfill (32,000 tonnes) following treatment. Nineteen per cent (9,400 tonnes) of back-loaded cuttings were recycled last year.
1
2
Figure 14: Disposal Route of Back-Loaded Cuttings from the UK Continental Shelf from 2001 to 2013
3
*
Landfill
Reuse and Recycle
Other
Incineration
Waste to Energy
0 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
4
5
Tonnes
6
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
7
*Other: Any other disposal route, includes composting, land spreading and treatment of aqueous wastes
Source: EEMS June 2014
8
3.6.3 Potential Environmental Impacts Wastes deemed hazardous only present a risk to the environment if they are improperly managed. Modern disposal and recycling techniques, such as engineered landfill, incineration and recovery of waste oils minimise the environmental impact.
Disposal to landfill is costly and is not sustainable in the long term. Operators segregate wastes to reduce the quantity of material going to landfill and to maximise reuse or recycling.
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ENVIRONMENT REPORT 2014
4. Accidental Oil and Chemical Releases 4.1 Introduction
The oil and gas industry does its utmost to prevent accidental oil and chemical releases by investing heavily in the provision of physical barriers, such as downhole safety valves, maintenance to minimise leaks, as well as in the development of handling procedures and training to influence human behaviours. 4.1.1 Oil Releases The UK is a signatory to the Oil Pollution Preparedness, Response and Co-operation Convention (OPRCC). TheConventionhas been implemented in theUK through theOffshorePetroleumActivities (Oil PollutionPrevention and Control) Regulations 2005 (as amended), which means it is an offence to make an unlawful discharge of oil (a discharge of oil other than in accordance with the permit granted). In addition, the Merchant Shipping (Oil Pollution Preparedness, Response and Co-operation Convention) Regulations 1998 introduced intoUK law the oil spill planning requirements and legal oil spill reporting requirements of the OPRCC. Under these Regulations, operators must have approved Oil Pollution Emergency Plans (OPEPs) in place that detail response plans in the event of an accidental release. The level of response is predetermined through installation-specific risk assessments that take into account the type of oil, the location’s environmental sensitivities and the likely movement of the oil using modelling. Depending on the level of risk, the response will range from surveillance to monitoring an oil slick’s behaviour, through to the use of chemical dispersants and physical containment and recovery. A high level of preparedness is maintained in the industry through regular oil spill response training, five-yearly OPEP reviews and demonstration of the effective use of response equipment through exercises. 4.1.2 Chemical Releases Accidental chemical releases are subject to the Offshore Installations (Emergency Pollution Control) Regulations 2002 and the Offshore Chemicals Regulations 2002 (as amended). These Regulations require that chemical use and discharge at offshore oil and gas installations is covered by a permit system. Exceeding discharge limits must be reported. The nature of chemicals means that there is significant mixing and dilution of the release substance(s) into the water column, therefore, the response to an accidental chemical release differs greatly to that of an oil release. As per the Guidance Notes on the Offshore Chemicals Regulations 2002 (as amended), upon notification of a chemical release, the DECC Inspectorate will advise on the appropriate course of action.
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4.1.3 Reporting Releases The UK offshore oil and gas industry reports hydrocarbon releases (HCRs), including oil, gas and condensate releases, to the Health and Safety Executive (HSE). The HCR database, accessible on the HSE website 15 , includes incidents that are reportable under the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR), as well as supplementary detail voluntarily provided by operators. HCR releases are confirmed unintentional releases that are reportable if they: • Result in a fire or explosion • Initiate automatic executive action • Require the taking of other actions to prevent or limit the potential for death or a specified injury to any person Whether releases are deemed reportable or not depends on factors such as the release rate and volume of the release. These releases may be made to the atmosphere, to the marine environment, or the installation and are then contained. Releases are reported under three severity classifications: major, significant and minor. All accidental chemical and oil releases to the marine environment are also reportable to DECC through the submission of a Petroleum Operations Notice 1 (PON 1). This PON1 data differs from the HCR data because it includes all releases, regardless of their size, that reach the sea. PON1 data are published on DECC’s website 16 and updated regularly. The trend data below presents an overview of the number and volume of releases to the marine environment over the past decade using the PON1 dataset, supplemented by data from EEMS 17 . Further detailed analysis of the data from 2011 to 2013 explores the distribution of release size, sources and chemical hazard levels. The HCR and PON1 data have been treated separately in Oil & Gas UK’s Health & Safety Report 2014 and Environment Report 2014 , respectively, because of the difference in data coverage. Many of the initiatives to manage releases by industry are likely to affect the number of both HCR and PON1 releases. 4.2 Trend Data Although the number of releases can appear significant, it is important to note that the UK offshore oil and gas industry is committed to transparency in reporting and all releases to the marine environment, no matter how small, are reportable as a PON1. Given that the releases are unplanned, they cannot always be measured, therefore, estimation is used to determine a release volume. Commonly, the approach taken is to report the worst case estimate meaning that the volume actually released is often lower than the volume reported. Once reported, PON1s undergo a period of investigation by DECC and the operator, classified as ‘under review’. After the investigation has been completed, the details of the accidental release, including volumes, are made available. The figures below include the total number of PON1s, both complete and under review. Full details, including volumes, were not available for releases classified as ‘under review’ in April 2014 (157, or one tenth of the releases from 2011 to 2013) and, therefore, those volumes have not been included in the analysis.
1
2
3
4
5
6
7
8
15 The HCR database is available to view at www.hse.gov.uk/offshore/hydrocarbon.htm 16 The PON1 data are available to view at www.og.decc.gov.uk/eng/fox/pon1/PON1_PUBLICATION_EXTERNAL/viewCurrent 17 Both the PON1 and EEMS datasets were analysed as at April 2014
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