alma field development environmental statement

EnQuest Heather LimitedAlma Field Development Environmental StatementDECC Document Ref: D/4110/2011Intertek METOC Document Ref: P1459BA_RN2525_Rev0EnQuest Heather Limited Document Ref: ENQ-KN501-HS-001-ENS-0001ISSUED: 21 JULy 2011

WHERE ENGINEERING MEETS THE ENVIRONMENT

ENQUEST HEATHER LIMITED ALMA FIELD DEVELOPMENT

REPORT REF: P1459BA_RN2525_REV0 21/07/2011

STANDARD INFORMATION SHEET Project Name Alma Field Development DECC Reference Number D/4110/2011

Type of Project Small oil field development Undertaker Name EnQuest Heather Limited Undertaker Address 5 Floor Consort House, Stell Road, Aberdeen, AB11 5QF, United Kingdom Licencees / Owners EnQuest Heather Limited (100%)

Short Description

EnQuest Heather Limited wishes to redevelop the Ardmore field in the UK Central North Sea (CNS). The field, to be renamed Alma, will be developed through two drill centres tied-back via new oil production and water injection flowlines to the Uisge Gorm floating production, offloading and storage facility (FPSO). The development will consist of six production wells and two water injection wells (which will be used to drive production due to low reservoir pressures). Wells will be drilled using a combination of water and oil based muds. Cuttings and water based muds will be discharged to sea both at the seabed and from the drilling rig approximately 10m below the sea surface. Oil based mud and cuttings will not be discharged and will be skipped and shipped back to shore for disposal. Due to the relatively short expected field life of the Alma development (ten years), the Uisge Gorm FPSO will be used instead of installing a platform. Produced crude will be collect by shuttle tanker once every two weeks. The majority of the produced gas will be used for power generation, however there may be a short period early part of field life where excess gas is produced that cannot be burned, this will be flared. All produced water will be re-injected. Production flowlines will be surface laid and protected. The water injection flowline will be trenched and buried, but where trenching is not possible it will be surface laid and protected. Concrete mattresses and rock material will be used for protection. Current estimates are that based on a 10 year field life the base case recovery from the Alma field will be 20.7 million barrels (2.8 million tonnes) and a high recovery case of 32.5 million barrels (4.4 million tonnes). Peak production in the first year will be in the region of 4.5 million barrels (0.61 million tonnes) for the base case and 7.8 million barrels (1.06 million tonnes) for the high recovery case. Construction is scheduled to start in January 2012 with the drilling of the first producer wells. First oil is anticipated in August 2013.

Anticipated Start of Works January 2012

Previous / Other Statements Related to this Project

N/A

Significant Environmental Impacts Identified

EnQuest is aiming to limit environmental effects to low impact through project design, mitigation measures and operational controls. No impacts associated with the development have been categorised as Major or Critical, meaning that the majority of the impacts were assessed as having no or minor residual impact (i.e., impacts can be managed through effective standard operating procedures). A few impacts were assessed as Moderate (i.e., the residual impact has been subject to feasible and cost effective mitigation and no further measures are practicable). During construction and production it is considered that the following activities may have an impact: on the environment; atmospheric emissions from power generation; anchoring ; discharge of chemicals and drill cuttings; positioning of structures, rock material and concrete mattressing on the seabed; and the accidental spill of hydrocarbons and/or chemicals. However in all instances the severity of the impact is limited by the nature and composition of the environment and by the fact that these activities are short-term and affect a localised area. With mitigation measures in place, the Alma field development will have a minor impact on the environment.

Statement Prepared By Intertek METOC and EnQuest Heather Limited



NON-TECHNICAL SUMMARY INTRODUCTION

EnQuest Heather Limited wishes to redevelop the Ardmore field in the UK Central North Sea

(CNS). The field, to be renamed Alma, will be developed through two drill centres tied-back

via new oil production and water injection flowlines to a floating production, offloading and

storage facility (FPSO). Export will be through the use of a shuttle tanker from the FPSO.

The proposed Alma development will be located in United Kingdom continental shelf (UKCS)

Blocks 30/24 and 30/25, approximately 274km east of the nearest landfall on the

Northumberland coastline and approximately 18.5km from the Norway/UK international

boundary (median line).

In compliance with regulatory requirements, and to responsibly manage any impacts from the

development, EnQuest has carried out an Environmental Impact Assessment (EIA) of the

proposed development.

The EIA process establishes the environmental baseline in the area of the proposed

development and identifies environmental sensitivities, particularly with relevance to the

concerns of stakeholders and regulatory bodies. It also evaluates relevant environmental

impacts and their significance, and finally proposes mitigation measures which the operator

will implement to minimise these impacts.

This document reports on the EIA process, its findings and conclusions.

GOVERNING LEGISLATION

Offshore oil and gas developments are governed by a collection of international, European

Community (EU) and UK laws, policies and guidelines. These dictate the management goals

and objectives which an environmental assessment may aim to achieve. The main UK

regulations that apply to the project are:

Petroleum Act 1998 Requires all offshore oil and gas development to apply for

consent to undertake the project.

Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects)

(Amendment) Regulations 2007 These regulations implement the EC EIA and Public

Participation Directive, and require an ES to be submitted for offshore oil and gas

projects and public participation in the consent process.



Offshore Marine Conservation (Natural Habitats, &c.) Regulations 2007 (as amended

in 2009 and 2010) These regulations implement in the UK the EC Habitats Directive

(92/43/EC) and the EC Birds Directive (79/409/EC) and aim to protect marine species

and wild birds from environmentally damaging activities. It is now an offence under the

Regulations to deliberately disturb wild animals of a European Protected Species.

Offshore Petroleum Activities (Conservation of Habitats) Regulations 2001 (amended

in 2007) The regulations apply the EC Habitats and EC Birds Directives in relation to

oil and gas projects on the UKCS.

PROJECT JUSTIFICATION

Oil is the UKs second largest source of primary energy, supplying over 30% of the countrys

total energy needs (OGUK 2009). In 2008, the UKCS oil production was enough to satisfy

97% of domestic consumption, produced mainly from fields in the Central North Sea (CNS)

basin, with some production in the NNS and Southern North Sea (SNS). In 2000, the UK

Government identified the need to stimulate oil and gas investment and activity to ensure

that indigenous production of oil and gas remained at significant levels into the future. The

Promote UK campaign is designed to attract new entrants onto the UKCS, and focused on:

Independent oil companies with the resources to drill wildcat exploration wells and

exploit the full value chain from exploration to development; and

Niche developers, particularly those with the skills to develop previously undeveloped

discoveries by using technically innovative and best cost solutions (DECC 2011a).

As a result of these initiatives, EnQuest has been active on the UKCS since 2010. It

specialises in predominantly mature areas of the NNS and CNS, aiming to maximise the

potential from existing fields and future developments in the UKCS. The longer term strategy

is to become a prominent exploration and development operator.

The Alma Field development is part of this strategy and fits many of the UK energy policy

objectives:

It would bring on-stream a marginal field that it is now feasible to develop with the

prevailing oil price and the small field allowance applicable to this size of field

It is a national resource that will help contribute towards energy security



Current estimates predict that P501 recovery over field life will be 20.7 million barrels of oil (2.8 million tonnes). P102 recovery is estimated to be 32.5 million barrels (4.4 million tonnes).

PROJECT ALTERNATIVES

EnQuest have considered a number of development options for the Alma field. Given the

compact nature of the field and relatively short field life, the decommissioning strategy has

played an important role in option selection. Options considered included the choice of

surface facilities (FPSO, floating production facility (FPF), platform or subsea tie-back), the

choice of drilling rig (semi submersible or heavy duty jack-up) and the installation philosophy

of the flowlines (trenched and buried or surface laid and protected).

After considerable deliberation, the FPSO, semi submersible and a combination of trenching

and surface lay options were selected, based on combination of technical, environmental

economic considerations. Table 3-3 details all the pros and cons of each option.

FPSO

A number of FPSOs are available for deployment

Provides an integrated storage and offloading system

Modifications required are more economic that other available options e.g. new

platform

FPSOs fit for expected field life

Using an existing FPSO is cheaper than a new build

FPSOs considered have proven track record in the UKCS

Minimal seabed disturbance from installation

Can be easily redeployed at end of field life

Semi Submersible

Less weather dependant during positioning on site

More scope for moving rig but maintaining same anchor pattern less seabed

disturbance. For example, moving to allow subsea infrastructure to be installed,

moving rig if subsurface philosophy changes

1 50% confidence level of this volume of oil being produced 2 10% confidence level of this volume of oil being produced



Ability to drill six wells on same anchor pattern less seabed disturbance

Easier to run horizontal xmas trees

Better selection options- at least two rigs are known to be available

Current drilling team has extensive knowledge of semi submersible drilling operations

Flowlines

Buried

Greater protection for flowlines no additional protection such as rock would be

required except for mattressing and grouting at trench transition areas

Conventional / proven solution

Option to surface protect spans which cannot be buried due to existing subsurface

obstructions

Surface Laid

Ease of installation - range of installation vessels available

Benefit as compact field layout with possible drilling rig on site during installation

Lower mobilisation costs for installation

Potential of re-use / decommissioning easier

Conventional / proven solution

Minimal seabed disturbance

Lower risk of subsurface obstructions because no trenching

Additional protection such as rock material will be required for certain spans

Technically preferred option for production flowlines due to temperature issues

PROJECT DESCRIPTION

SCHEDULE

Construction is scheduled to start in January 2012 with the drilling of the first production well.

Construction activities will continue through to May 2013 with first oil expected in third quarter

2013. A total of six production wells and two water injector wells will be batch drilled and are



expected to take approximately three months each to drill and complete. Field life is

anticipated to be ten years.

CONSTRUCTION

The development will consist of:

The drilling of six producers and two water injectors

The Uisge Gorm FPSO

Two 10-inch production flowlines, one 10-inch water-injection flowline, two control

umbilicals and one power cable

Production wells will target a total of three reservoirs within the Alma Development area:

Devonian, Zechstein and Rotliegend. Three production wells will be drilled in five sections

using a combination of water based mud (WBM) and oil based mud (OBM), with each

section cement cased. The remaining three production wells and the two water injection

wells will be drilled in four sections also using a combination of WBM and OBM, with each

section cement cased. Cuttings and WBM will either be discharged at the seabed or to sea

approximately 10m below sea surface from the drilling rig. All OBM and cuttings will be

skipped and shipped to shore for disposal.

The water injection flowline will be trenched and backfilled. In the event of any undulations in

the trench (and subsequently the flowline) a contingency will be in place for the provision of

approximately 5,000 tonnes of rock for deposition for protection. The rock will be deployed to

mitigate any upheaval buckling (less of a problem with flexible flowlines) or pipeline out of

straightness events experienced during the trenching and pipe-lay activities. This may be

required for pipeline protection, depth of cover anomalies or dropped object protection. The

requirement for rock deposition will be identified during post lay survey and if required the

rock will be placed accurately utilising a dynamically positioned fall pipe rock installation

vessel. The vessel will be equipped with a fall pipe to deploy rock accurately in the spot

location. Where trenching is not possible the water injection flowline will be surface laid and

protected where required with concrete mattress to eliminate any pipe-spans or seabed

obstructions. The production flowlines will be surface laid and protected. They cannot be

trenched as the arrival temperature of the production fluids at the FPSO would be too high.

After tie-in, the flowlines will be hydrotested and leak tested before being dewatered and then

commissioned. Concrete mattresses and rock material will be used for dropped object

protection and stability. The water-injection flowlines will terminate directly in the FPSO. The

production flowlines will terminate at a bolted straight T piece from which flexible risers will



take produced fluids to the FPSO. All flexible risers will be secured by either vertical piled or

gravity base anchors and horizontal clump weight anchors.

The Uisge Gorm FPSO will be held permanently on station without any aid from thrusters or

other external sources by nine anchors. Modifications and upgrades will be carried out on

the FPSO turret to accommodate the new flowline/umbilical riser systems required to receive

and process the Alma hydrocarbons and to export injected water. The upgrades will be

finished before the FPSO is mobilised to the field.

Note: Image is for illustrative purposes only and does not necessarily reflect exact layout of flowlines and associated infrastructure

PRODUCTION

Produced crude oil and associated gas will be produced back to the FPSO and oil then

offloaded onto shuttle tankers for export.

First oil is currently expected in third quarter 2013. Current estimates are that based on a 10

year field life the base case recovery from the Alma field will be 20.7 million barrels (2.8

million tonnes) of crude oil and a high recovery case of 32.5 million barrels (4.4 million

tonnes). Peak production in the first year will be in the region of 4.5 million barrels (0.61



million tonnes) for the base case and 7.8 million barrels (1.06 million tonnes) for the high

recovery case. The reservoir pressure at Alma is such that produced water re-injection is

required to ensure that satisfactory quantities of crude oil are produced. Sufficient quantities

of gas are expected to be produced with the crude to be used for power generation onboard

the FPSO.

Produced water will be passed through a bank of hydrocyclones which will take oil in water

(OIW) concentrations from approximately 1000mgl-1 to below 30mgl-1. It will then be routed

through a degasser and settling vessel. The produced water then passes through the pumps

past an overboard discharge point and into four injection pumps that push the produced

water down the water injection flowline to be re-injected. Should any produced water be

discharged (due to temporary failure, or routine maintenance of the produced water re-

injection system) then OIW concentrations will be below 30mgl-1.

Early in the field life there will be the need to flare gas. This would be due to either

insufficient gas production to power the generators on the FPSO or because of an excess of

gas produced, over that demanded for fuel.

DECOMMISSIONING

Field life is expected to be ten years. Before the end of field life, arrangements for

decommissioning will be developed in accordance with the prevailing UK government and

international legislation. The development plan is based on the assumption that similar

requirements to current legislation will be applicable. These requirements have been

considered in the design of the facilities and during project planning. The impacts of

decommissioning activities on the environment have not been assessed under the scope of

this document as they will be the subject of a separate EIA.

ENVIRONMENTAL IMPACT AND MITIGATION

Mitigation is an integral part of the Alma development. All of the potential interactions

between project activities and environmental receptors are subject to either standard

recognised best practice mitigation measures or to impact specific, feasible and cost

effective mitigation. In general, the mitigation proposed will be sufficient to reduce the effects

of activities to below levels which will cause a significant residual impact. For those where

mitigation isnt enough, the residual impacts are detailed below with a discussion of the

mitigation that will help to reduce the impact to the acceptable levels identified.



The following table summarises the findings of the detailed EIA process undertaken in

relation to the Alma development and outlines details of the impacts that were considered to

have a residual impact on the environment.

Receptor & Type of Impact

Baseline & Impact Assessment Significance of Residual Impact

Mitigation

Construction Seabed Conditions: Disaggregation of surface sediments Change in seabed topography

The Alma development area comprises a





Mitigation

Physical damage to individuals or habitats and smothering (Drill cuttings)

direct impact on the benthic community. Cuttings discharged through the water column could have an impact on the benthic community as they settle out on the seabed. Cuttings will be incorporated in the sediment through bioturbation and general sediment mobility. Significant erosion of cuttings piles starts when the seabed critical velocity reaches 0.35ms-1 (UKOOA 1999). Seabed currents (0.42ms-1) will ensure that all cuttings piles will disperse quickly, although there is the possibility that they may persist for a number of years. Experience in the CNS region indicates that cuttings piles will persist for 5-10 years.

No mitigation envisaged

Fish and Shellfish: Loss or disturbance of spawning and nursery grounds effecting stock viability

Mackerel, lemon sole, sprat, haddock and whiting all spawn and/or nurse in the vicinity of the Alma development. Spawning occurs mainly between April and September, with peaks in May, June and July. Juveniles may be present in the region all year round. As the majority of the noise generated by offshore oil installations is low frequency (





Mitigation

any residual impact after mitigation. production and water injection pipelines between the FPSO and the production and water injection drill centres The drilling rig and construction vessels will be appropriately lit and sound warnings will be broadcast in poor visibility. Users of the sea will be notified of the presence and intended movements of construction vessels via the Kingfisher fortnightly bulletins, Notices to Mariners and VHF radio broadcast.

Shipping and Navigation: Impact on vessel movement

The nearest shipping route is within 2nm of the Alma development. Some shipping will be displaced from the immediate vicinity of the development; however there is ample sea room to do so. The 500m safety exclusion zone around the drilling rig is intended to prevent potential collisions with any vessels that may be in the area. This will be enforced by a guard vessel.

Minor

Archaeology: Physical damage to undiscovered archaeology

It is unlikely that any remains of archaeological significance exist within the Alma area. However, the proposed mitigation measures would ensure damage to the site would be minimised and the nature of the discovery properly reported. It is therefore likely that any damage would be of minor significance, while the value of the discovery may be of moderate/major (positive) significance.

Minor The British Marine Aggregate Producers Association (BMAPA) protocol for reporting finds of archaeological significance will be followed

Production Commercial Fishing: Exclusion from fishing grounds Potential collision risk

The project area is not considered to be a commercially important for fishing. The continued presence of development and the exclusion zones around the drill centers and the FPSO will typically preclude fishing in this area due to the small development size.

Minor A 500m safety exclusion zone will be enforced around the FPSO. The FPSO will be appropriately lit and sound warnings will be broadcast in poor visibility. Users of the sea will be notified of the presence of the FPSO and new safety exclusion zones via the Kingfisher fortnightly bulletins, Notices to Mariners and VHF radio broadcast. All vessels will comply with international navigation regulations and codes.

Accidental Events Water Resource: Deterioration in water quality

Water quality is likely to deteriorate in the immediate vicinity of the spill (>10 tonnes) as hydrocarbons are dispersed through the water column. However, it will be naturally biodegraded by microbes within one to two months (NOAA 2006). The concentration and likelihood of natural biodegradation will obviously be dependent on the scale of the incident. However, generally the deterioration in water quality will be short term.

Minor Accidental spills will be kept to a minimum through training, good housekeeping and through storage/handling procedures e.g., sumps, drains and bunding should catch accidental spills. Management controls will be in place to eliminate bunkering spills e.g. only bunkering during day light and in good weather. A location specific OPEP will be in place for the drilling rig and an Addendum to the North Cormorant OPEP will be applied for to cover

Plankton: Potential toxic effect

Marine ecology is typical for the NNS with no rare or protected benthic species identified in the baseline survey. Nine cetacean species may occur in the area, all of which are protected under the EC Habitats Directive. The region is also

Minor

Benthic Communities:

Minor





Mitigation

Potential toxic effect

important for seabirds. Biological receptors are vulnerable to the accidental release of hydrocarbons and/or chemicals. Accidental events are extremely unlikely to occur. A small spill of diesel of crude will rapidly disperse and dilute in the energetic marine environment but a large spill as a result of a loss of containment on the export tanker and FPSO has the potential to have wider reaching impacts. Modelling suggest that under typical meteorological conditions, there is the potential for a oil slick as a result of the loss of the FPSO and export tanker inventory to beach along the coastlines of the majority of countries bordering the North Sea (total probability of beaching is 1%). Numerous protected areas could potentially be impacted as shown in Figure 8-4.

production operation. The OPEPs will detail all emergency procedures that will be in place to minimise any spill. EnQuest has access to Tier 1, 2 and 3 oil spill response capabilities through Oil Spill Response (OSR). EnQuest is a member of OSPRAG which will provide support in a well blow out event. Control measures will be in place to ensure rapid response to loss of flowline containment. These will be outlined in the Alma OPEP.

Fish and Shellfish: Potential toxic effect

Minor

Seabirds: Smothering

Moderate

Marine Mammals and Protected Species: Smothering

Minor

Commercial Fishing: Damage to vessels and decrease in catch

A major crude oil spill has the potential to cause damage to the fishing industry by long-term effects on fish stocks and damage to market confidence and could potentially exclude shipping from a number of key shipping lanes. However, the likelihood of such an event occurring is extremely rare.

Minor

Shipping and Navigation: Impact on vessel movement

Minor

Other Marine Users: Damage to vessels

Minor

CUMULATIVE AND INDIRECT IMPACTS

The main concerns regarding the potential for cumulative and indirect impacts from the

proposed development relate to impacts from activities at Alma interacting with:

Other activities within the project

Other oil and gas developments (past and future)

Other marine users, such as windfarms, commercial fishing, marine aggregate

extraction areas etc

Climate change

The EIA drew the following conclusions:

The project will not have any significant cumulative or indirect effects with any other oil

and gas developments



The project will not have any significant cumulative or indirect effects with any other

seabed users

The project will not exacerbate the changes predicted to occur as a consequence of

climate change.

The EIA identified the Alma development will not have any residual impacts on water depth,

wind speed or wave conditions. Residual impacts on the environment will be short-term,

predominantly affecting marine ecology. As climate change has the potential to affect the

biological baseline it is possible that the project can act in combination with climate change to

exacerbate this impact. However, the EIA concludes that, following construction, biological

communities are anticipated to recover to pre-impact levels/structures or similar within five

years (see Section 9.2.4.1). Given the relatively short timescale of the construction impacts,

it is considered unlikely that any cumulative impacts from the project and climate change will

have significant impacts on marine ecology.

ENVIRONMENTAL MANAGEMENT SYSTEMS

EnQuests corporate policies and environmental management system (EMS) provide a fit for

purpose framework to implement the mitigation measures proposed in the ES.

EnQuest is a socially responsible employer, committed to maintaining high standards in

health, safety and environmental performance. EnQuest implements and operates an

integrated Health, Safety and Environmental Management System (HS&EMS) and a Quality

Management System (QMS) which has been accepted and endorsed by the Board, and

embedded in the overall business culture. The HS&EMS is an integral part of the overall

management system. It is laid down in policies, procedures, standards and work

instructions. Its general purpose is to prevent EnQuests activities from putting people, the

environment, property or the reputation of the company at risk.

The HS&EMS is designed to match the requirements of ISO-14001:2004 and is based on the

requirements of the Health and Safety OHSAS 18001 standard. The QMS is certified to BS

EN ISO 9001. The purpose of the HS&EMS and QMS is to enhance health, safety,

environmental and quality (HSEQ) performance and provide a framework for HSEQ

management for all of the activities carried out throughout the company. The management

systems are designed to cover HSEQ aspects which EnQuest can control and directly

manage and those it does not control or directly manage, but can be expected to influence.

EnQuest requires all contractors, their subcontractors and suppliers to have their own

HS&EMS and QMS. Each contractor will be responsible for the HS&E management of their



scope of work and will operate according to their own HS&E Management System.

However, contractors HS&EMS must be compatible with EnQuests HS&EMS and they are

required to align their HS&E management with EnQuests goals and objectives. Their QMS

must meet the applicable requirements of the BS EN ISO 9000 series of standards or an

agreed equivalent.

A project specific HS&E plan will be developed for the Alma development which will define

how EnQuest will manage HS&E risks and activities. The Project HSEQ Engineer is

responsible for maintaining and implementing the plan, and for providing HSEQ controls

within the project to ensure that the requirements of the EnQuest HSEQ management

systems are met.

It is expected that the mitigation measures identified in the EIA process and reported in this

ES will be adopted and bridged into EnQuests HSEQ Management System through the

PLANC register.

CONCLUSIONS

EXISTING ENVIRONMENT

Existing conditions at the Alma development were established through an environmental

baseline and habitat assessment survey, which revealed that:

The benthic habitat typically comprised of sparse sandy sediments with low benthic

diversity. The majority of benthic taxa were polychaete worms. Stations sampled

where historical drilling activity was prevalent were characterised by more disturbance

and hydrocarbon contamination tolerant species and lower numbers of sensitive

species.

No habitats or species of conservation significance under the UKs Offshore Marine

Conservation (Natural Habitats, &c.) (Amendment) Regulations 2010 were observed

during seabed surveys

The environmental baseline is similar to other regions of the CNS where oil and gas activity

is prevalent. Meteorological conditions around the project support a dilution and dispersion

regime which will rapidly reduce the impact significance of emissions to air, water and

seabed (i.e. winds are sufficient to disperse atmospheric emissions, tidal currents refresh the

water column within an estimated 1.5 hours, currents are generally sufficient to disperse drill

cuttings or sediment piles on the seabed).



IMPACTS

The potential effects of the project on the environment were identified and quantified by

reviewing the existing baseline environmental conditions with the potential to be affected by

the project and identifying and evaluating the effect of any activities associated with the

project on these conditions.

It should be noted that the majority of activities were assessed as having no or minor residual

impact on the receiving environment, with a few identified as having a residual impact of

moderate significance. This ES reached the following conclusions with regards to the

projects impacts on the environment:

Benthic Environment: The total seabed footprint of the development is 0.04km2. Due to fishing activities and previous oil and gas industry activities, the benthos in the

project area is typical of a moderately disturbed habitat and consequently species that

inhabit the area tend to recover quickly after disturbance. The proposed development

is located within an area of previous drilling activity. The development area is

sufficiently homogenous that any localised losses are unlikely to affect the integrity of

the community as a whole. The placement of protective structures such as concrete

mattresses will create new habitat for those species that require hard substrate for

anchoring. This could lead to settlement of new species and the potential for a

localised change in marine ecology. Current speeds are sufficient to erode cuttings

piles and these are unlikely to persist for a long period of time.

Protected Species: No protected species were identified in the marine benthic surveys. Marine mammals are likely to be the only protected species of relevance to

the Alma development. Assuming the source to be near the seabed, for a receptor

10m below the surface, the noise would have reduced to approximately 153 dB SEL

vertically above the source. This is 7 dB below the lowest of the recognised

thresholds for strong avoidance behaviour (160 dB SEL) of marine mammals. In

conclusion, and provided mitigation measures are followed, the sound experienced will

not exceed the injury thresholds for marine mammals. There is therefore a negligible

risk of an offence under the Conservation (Natural Habitats &c) Regulations 1994 (as

amended) and the Offshore Marine Conservation (Natural Habitats &c) Regulation

2007 (as amended in 2010).

Protected Areas: There are no protected sites within 40km of the Alma development. The nearest protected site is the Dogger Bank potential Special Area of Conservation

(pSAC) which is approximately 78km south-east from the Alma southern drill centre.



Due to the distance of the protected site from the development area, it is unlikely that

there will be any impacts during normal activities.

Water/Sediment Quality: During normal activities, the production activities will have a negligible impact on the marine environment.

Commercial Fishing: With consideration of other development activities in the CNS, the project will have a minor contribution to seabed smothering from cuttings piles,

infrastructure installation and anchoring. However, this is anticipated to be limited to

within the immediate vicinity of the wells. Safety exclusion zones are likely to have a

moderate impact on commercial fishing in the area as this will result in vessels being

displaced from their fishing grounds. Overall it is concluded cumulative impacts and

the in-combination impacts with the fishing industry and other marine users are likely

to be of negligible significance.

Oil/Chemical Spill Pollution: In the unlikely event of a major oil spill, a worst case scenario loss of containment of 100,000m3 (87,000 tonnes) of crude oil from the

export tanker has been modelled. This indicates that there is a 1% chance of

beaching occurring on the majority of coastlines bordering the North Sea. Modelling

also indicates that the spill could reach the UK coastline within 8 days and 10 hours

and the Danish coastline within 5 days and 12 hours. The spill is likely to have

completed dispersed within 417 days. Numerous protected areas along the coastlines

of those North Sea countries that could be affected by a spill of this magnitude.

EnQuest will have an OPEP in place.

ENVIRONMENTAL MANAGEMENT

The EnQuest corporate policies and environmental management system provide a fit for

purpose framework to implement the mitigation measures proposed in this ES. The EMS

also provides adequate control and bridging arrangements for EnQuest to ensure that the

contractors implement these mitigation measures. During the construction and production

operations, a set of permits and consents will be obtained from the regulatory bodies. Permit

conditions under these will also be fed into the EMS to ensure compliance. EMS

performance will be regularly benchmarked against recommendations from independent

verifications, through internal and independent audits and reviews.

With mitigation measures in place, the Alma Field development will have a minor

impact on the environment.



CONTENTS 1 INTRODUCTION ............................................................................................. 1-11.1 THE DEVELOPER ............................................................................................... 1-11.2 PROJECT OVERVIEW .......................................................................................... 1-11.3 FORMAT OF THE ENVIRONMENTAL STATEMENT .................................................... 1-61.4 ES AVAILABILITY ............................................................................................... 1-7

2 INSTITUTIONAL, POLICY AND REGULATORY FRAMEWORKS ............... 2-1

2.1 RELEVANT POLICY GUIDELINES .......................................................................... 2-12.2 INTERNATIONAL CONVENTIONS, EC AND UK LAWS AND REGULATIONS .................. 2-12.3 SEA AND EIA GUIDELINES ................................................................................. 2-52.4 UK INSTITUTIONAL FRAMEWORK ......................................................................... 2-62.5 ENQUEST CORPORATE POLICY .......................................................................... 2-6

3 PROJECT JUSTIFICATION AND ALTERNATIVES ...................................... 3-1

3.1 PROJECT JUSTIFICATION .................................................................................... 3-13.2 ALTERNATIVES .................................................................................................. 3-3

4 IMPACT ASSESSMENT METHODOLOGY ................................................... 4-1

4.1 ENVIRONMENTAL AND HUMAN IMPACT ASSESSMENT PROCESS ............................. 4-14.2 CUMULATIVE AND INDIRECT IMPACTS ................................................................. 4-124.3 EIA STAKEHOLDER CONSULTATION .................................................................. 4-13

5 PROJECT DESCRIPTION .............................................................................. 5-1

5.1 SCHEDULE ........................................................................................................ 5-25.2 CONSTRUCTION ACTIVITIES ................................................................................ 5-25.3 PRODUCTION OPERATIONS ............................................................................... 5-165.4 DECOMMISSIONING .......................................................................................... 5-195.5 PROJECT ACTIVITY SUMMARY ........................................................................... 5-20

6 PROJECT FOOTPRINT ................................................................................. 6-1

6.1 CONSTRUCTION ................................................................................................. 6-16.2 PRODUCTION .................................................................................................. 6-11

7 ACCIDENTAL EVENTS ................................................................................. 7-1

7.1 TYPES OF ACCIDENTAL EVENT ............................................................................ 7-1



7.2 PROBABILITY OF ACCIDENTAL EVENTS OCCURRING .............................................. 7-47.3 OIL SPILL MODELLING ........................................................................................ 7-6

8 IMPACTS ON PHYSICAL ENVIRONMENT ................................................... 8-1

8.1 AIR ................................................................................................................... 8-18.2 CLIMATE CHANGE .............................................................................................. 8-68.3 WATER RESOURCES .......................................................................................... 8-98.4 SEABED CONDITIONS ....................................................................................... 8-16

9 IMPACTS ON BIOLOGICAL ENVIRONMENT ............................................... 9-1

9.1 PLANKTON ........................................................................................................ 9-19.2 BENTHIC COMMUNITIES ...................................................................................... 9-39.3 FISH AND SHELLFISH .......................................................................................... 9-69.4 SEABIRDS ....................................................................................................... 9-119.5 MARINE MAMMALS ........................................................................................... 9-179.6 PROTECTED SITES AND SPECIES ...................................................................... 9-25

10 IMPACTS ON HUMAN ENVIRONMENT ...................................................... 10-1

10.1 COMMERCIAL FISHERIES .................................................................................. 10-110.2 SHIPPING AND NAVIGATION .............................................................................. 10-710.3 OTHER MARINE USERS .................................................................................. 10-1110.4 ARCHAEOLOGY .............................................................................................. 10-15

11 CUMULATIVE AND INDIRECT IMPACTS ................................................... 11-1

11.1 OTHER OIL AND GAS DEVELOPMENTS ............................................................... 11-111.2 OTHER SEABED USERS .................................................................................... 11-511.3 CLIMATE CHANGE ............................................................................................ 11-6

12 ENVIRONMENTAL MANAGEMENT ............................................................ 12-1

12.1 MANAGEMENT SYSTEM .................................................................................... 12-112.2 PROJECT SPECIFIC ENVIRONMENTAL MANAGEMENT ........................................... 12-112.3 MANAGEMENT OF MITIGATION MEASURES ......................................................... 12-312.4 OIL SPILL RESPONSE ....................................................................................... 12-5

13 CONCLUSIONS ............................................................................................ 13-1

13.1 THE PROJECT ................................................................................................. 13-113.2 EXISTING ENVIRONMENT .................................................................................. 13-1



13.3 POTENTIAL IMPACTS ........................................................................................ 13-213.4 DECOMMISSIONING .......................................................................................... 13-313.5 ENVIRONMENTAL MANAGEMENT ....................................................................... 13-3

14 REFERENCES .............................................................................................. 14-1

APPENDIX A ENVIRONMENTAL IMPACT ASSESSMENT ................................ A-1

A.1 INTERACTION MATRIX......................................................................................... A-2A.2 CONSTRUCTION ................................................................................................. A-3A.3 PRODUCTION .................................................................................................. A-20A.4 ACCIDENTAL EVENTS ....................................................................................... A-32

APPENDIX B OIL SPILL MODELLING ................................................................ B-1

B.1 INTRODUCTION .................................................................................................. B-2B.2 ALMA FIELD DEVELOPMENT ................................................................................ B-2B.3 WORST CASE OIL SPILL MODELLING ................................................................... B-3B.4 SPILL SCENARIOS AND MODELLING RESULTS ....................................................... B-4B.5 ENVIRONMENTAL IMPACT ASSESSMENT ............................................................. B-13B.6 REFERENCES .................................................................................................. B-14

APPENDIX C SUMMARY OF CHEMICALS ......................................................... C-1

C.1 DRILLING CHEMICALS ......................................................................................... C-2C.2 CEMENTING CHEMICALS ..................................................................................... C-6C.3 COMPLETION AND OTHER CHEMICALS ................................................................. C-6C.4 PIPELINE CHEMICALS ......................................................................................... C-8

APPENDIX D JNCC RISK ASSESSMENT FLOW CHARTS ............................... D-1



TABLES TABLE 1-1: PROJECT CO-ORDINATES 1-3TABLE 1-2: STRUCTURE OF THIS ES 1-6TABLE 3-1: CUMULATIVE (BY YEAR) PRODUCTION PROFILES 3-2TABLE 3-2: PROS AND CONS OR DIFFERENT DEVELOPMENT SCENARIOS 3-6TABLE 4-1: PROJECT ACTIVITIES 4-6TABLE 4-2: EXTRACT FROM THE ALMA ISSUES SCOPING MATRIX 4-7TABLE 4-3: EXAMPLE DEVELOPMENT ACTIVITY, ASPECT AND IMPACT IDENTIFICATION 4-7TABLE 4-4: ASSESSMENT PROCESS FOR IDENTIFICATION OF POTENTIAL IMPACTS 4-8TABLE 4-5: SEVERITY DEFINITIONS 4-9TABLE 4-6: ENVIRONMENTAL AND HUMAN IMPACT SIGNIFICANCE ASSESSMENT MATRIX 4-10TABLE 5-1: PROJECT SCHEDULE 5-2TABLE 5-2: CURRENT UNMODIFIED UISGE GORM VESSEL AND PERFORMANCE DATA 5-3TABLE 5-3: SACRIFICIAL ANODE COMPOSITION 5-15TABLE 5-4: SUMMARY OF PROJECT ACTIVITIES AND ASPECTS 5-20TABLE 6-1: CONSTRUCTION EXHAUST GAS EMISSIONS 6-1TABLE 6-2: SUMMARY OF CONSTRUCTION NOISE SOURCES AND ACTIVITIES 6-2TABLE 6-3: SUMMARY OF CHEMICAL DISCHARGES (TONNES) ONE WELL 6-3TABLE 6-4: SUMMARY OF CHEMICAL DISCHARGES (TONNES) EIGHT WELLS 6-3TABLE 6-5: SUMMARY OF FLOWLINE DISCHARGES 6-4TABLE 6-6: SUMMARY OF DISCHARGES FROM WELL TIE-IN 6-4TABLE 6-7: TOTAL WASTE WATER DISCHARGE (M3) DURING CONSTRUCTION 6-5TABLE 6-8: SUMMARY OF UNDERWATER NOISE PRODUCED DURING CONSTRUCTION ACTIVITIES

6-5TABLE 6-9: WEIGHT AND DISCHARGE FATE OF DRILL CUTTINGS (TONNES) 6-7TABLE 6-10: SUMMARY OF FLOWLINE INSTALLATION FOOTPRINT ON THE SEABED 6-8TABLE 6-11: SUMMARY OF SEABED FOOTPRINT - FIELD DEVELOPMENT 6-10TABLE 6-12: EMISSIONS FROM POWER GENERATION 6-11TABLE 6-13: CO2 EMISSIONS FOR THE STEAM BOILER FROM POWER GENERATION 6-12TABLE 6-14: FLARING GAS EMISSIONS DURING PRODUCTION 6-12TABLE 6-15: PRODUCTION - VESSEL EXHAUST GAS EMISSIONS 6-13TABLE 6-16: SUMMARY OF PRODUCTION NOISE SOURCES AND ACTIVITIES 6-13TABLE 6-17: TOTAL WASTE WATER DISCHARGE PER ANNUM FOR FIELD LIFE 6-14TABLE 6-18: ALMA CHEMICAL INJECTION REQUIREMENTS 6-15



TABLE 7-1: INDUSTRY RISER AND PIPELINES FAILURE FREQUENCIES 7-6TABLE 8-1: ANNUAL WIND PERCENTAGE FREQUENCY DISTRIBUTION AT STANDARD HEIGHT (10M)

8-3TABLE 8-2: AIR QUALITY POTENTIAL IMPACT IDENTIFICATION 8-5TABLE 8-3: RECOMMENDED CONTINGENCY ALLOWANCES FOR NET SEA LEVEL RISE 8-7TABLE 8-4: CLIMATE CHANGE POTENTIAL IMPACT IDENTIFICATION 8-7TABLE 8-5: COMPARISON OF UK AND ALMA CO2 EMISSIONS - ANNUAL 8-9TABLE 8-6: PHYSICAL CHARACTERISTICS OF THE SEA WATER IN THE ALMA FIELD 8-10TABLE 8-7: SUMMARY OF NORTH SEA SURFACE WATERS CONTAMINANT LEVELS 8-10TABLE 8-8: SUMMARY OF TIDAL CURRENT SPEEDS AT THE ALMA FIELD 8-11TABLE 8-9: WAVE CHARACTERISTICS AT ALMA 8-13TABLE 8-10: MONTHLY WAVE HEIGHT AT ALMA 8-13TABLE 8-11: WATER RESOURCES POTENTIAL IMPACT IDENTIFICATION 8-14TABLE 8-12: WATER DEPTH 8-17TABLE 8-13: HEAVY METALS IN SEDIMENT (G.G-1) 8-23TABLE 8-14: SEABED CONDITIONS POTENTIAL IMPACT IDENTIFICATION 8-25TABLE 9-1: PLANKTON POTENTIAL IMPACT IDENTIFICATION 9-2TABLE 9-2: CONTRIBUTIONS OF THE GROSS TAXONOMIC GROUPS 9-4TABLE 9-3: SPECIES RANKING 9-4TABLE 9-4: BENTHIC COMMUNITIES POTENTIAL IMPACT IDENTIFICATION 9-2TABLE 9-5: COMMONLY CAUGHT SPECIES 9-7TABLE 9-6: KEY SENSITIVE PERIODS FOR FISH SPAWNING AND NURSERY 9-7TABLE 9-7: FISH AND SHELLFISH POTENTIAL IMPACT IDENTIFICATION 9-8TABLE 9-8: SEABIRD VULNERABILITY 9-13TABLE 9-9: SEABIRDS POTENTIAL IMPACT IDENTIFICATION 9-13TABLE 9-10: CETACEAN OBSERVATIONS IN THE AREA OF INTEREST 9-18TABLE 9-11: CETACEAN POPULATION ESTIMATES AND CONSERVATION STATUS 9-19TABLE 9-12: MARINE MAMMALS POTENTIAL IMPACT IDENTIFICATION 9-20TABLE 9-13: SOUND EXPOSURE LEVELS AT DISTANCE 9-23TABLE 9-14: PROTECTED SITES AND SPECIES POTENTIAL IMPACT IDENTIFICATION 9-27TABLE 10-1: VALUE () OF LANDING FOR THE ALMA DEVELOPMENT AREA AND SURROUNDING

REGION (2004 2009) 10-2TABLE 10-2: COMMERCIAL FISHING POTENTIAL IMPACT IDENTIFICATION 10-5TABLE 10-3: SHIP ROUTES 10-8TABLE 10-4: SHIP/INSTALLATION COLLISION FREQUENCIES ESTIMATED FOR ALMA FPSO 10-9



TABLE 10-5: SHIPPING AND NAVIGATION POTENTIAL IMPACT IDENTIFICATION 10-10TABLE 10-6: WELLS WITHIN 40KM OF THE DEVELOPMENT 10-12TABLE 10-7: OTHER MARINE USERS POTENTIAL IMPACT IDENTIFICATION 10-13TABLE 10-8: ARCHAEOLOGY POTENTIAL IMPACT IDENTIFICATION 10-17TABLE 12-1: ENQUEST ENVIRONMENTAL TARGETS 12-2TABLE 12-2: SUMMARY OF MITIGATION MEASURES 12-4TABLE B-1: PROJECT CO-ORDINATES B-2TABLE B-2: SPILL SCENARIOS MODELLED B-5TABLE B-3: MODELLING RESULTS B-5

FIGURES FIGURE 1-1: PROJECT LOCATION 1-2FIGURE 1-2: FPSO RISER HOLD-BACK TETHER EXAMPLE 1-4FIGURE 2-1: ENQUEST ENVIRONMENTAL POLICY 2-7FIGURE 3-1: CUMULATIVE (BY YEAR) PRODUCTION PROFILES 3-3FIGURE 4-1: OVERVIEW OF EIA METHODOLOGY 4-1FIGURE 4-2: ALMA DEVELOPMENT SURVEY EXTENTS 4-4FIGURE 5-1: ALMA FIELD DEVELOPMENT 5-1FIGURE 5-2: UISGE GORM FPSO 5-3FIGURE 5-3: TURRET MOORING SYSTEM 5-4FIGURE 5-4: FIELD LAYOUT SHOWING FPSO AND DRILLING RIG ANCHOR PATTERNS 5-5FIGURE 5-5: TYPICAL SEMI-SUBMERSIBLE DRILLING RIG 5-6FIGURE 5-6: TYPICAL TOP HAT RISER TETHER UTILISING PILES 5-10FIGURE 5-7: TYPICAL JET TRENCHING ROV 5-12FIGURE 5-8: OFFLOADING FROM UISGE GORM FPSO 5-16FIGURE 5-9: CUMULATIVE TOTAL CO2 (TONNES) FROM UISGE GORM FPSO (JAN-AUG 2008)

5-17FIGURE 6-1: AREA OF SEABED COVERED BY 1 WELL CUTTINGS PILE 6-8FIGURE 7-1: STOCHASTIC MODEL RUN 100,000M3 INSTANTANEOUS SPILL OF 38 API CRUDE

OIL (417 DAYS) 7-8FIGURE 7-2: POSSIBLE BEACHING LOCATIONS 7-8FIGURE 7-3: STOCHASTIC MODEL RUN 5,830M3 INSTANTANEOUS SPILL OF DIESEL 7-9FIGURE 7-4: SPILL TRAJECTORY UNDER 30 KNOT WIND CONDITIONS TOWARDS THE UK

COASTLINE 7-10



FIGURE 7-5: SPILL TRAJECTORY UNDER 30 KNOT WIND CONDITIONS TOWARDS THE NEAREST INTERNATIONAL BOUNDARY 7-10

FIGURE 7-6: DIESEL SPILL TRAJECTORY UNDER 30 KNOT WIND CONDITIONS TOWARDS THE UK COASTLINE 7-11

FIGURE 7-7: DIESEL SPILL TRAJECTORY UNDER 30 KNOT WIND CONDITIONS TOWARDS THE NEAREST INTERNATIONAL BOUNDARY 7-11

FIGURE 8-1: ANNUAL WIND ROSE FOR THE ALMA AREA 8-4FIGURE 8-2: GENERAL CURRENT CIRCULATION IN THE NORTH SEA 8-12FIGURE 8-3: BATHYMETRY AT NORTHERN DRILL CENTRE 8-18FIGURE 8-4: BATHYMETRY AT SOUTHERN DRILL CENTRE 8-19FIGURE 8-5: BATHYMETRY AT FPSO LOCATION 8-20FIGURE 8-6: EXAMPLE OF SEABED SEDIMENTS FROM SURVEY 8-21FIGURE 8-7: SAMPLING STATIONS LOCATION OVERVIEW 8-24FIGURE 9-1: SEABED PHOTOGRAPHS OF THE ALMA DEVELOPMENT AREA 9-5FIGURE 9-2: ENVIRONMENTAL OVERVIEW 9-12FIGURE 9-3: OIL SPILL BEACHING LOCATIONS IN RELATION TO PROTECTED SITES 9-29FIGURE 10-1: SEASONAL VARIATION IN FISHING ACTIVITY (2004-2009) 10-3FIGURE 10-2: AVERAGE ANNUAL CATCH AND VALUE FOR THE ALMA DEVELOPMENT AREA 10-4FIGURE 10-3: SHIPPING ROUTE POSITIONS WITHIN 10NM OF ALMA LOCATIONS 10-8FIGURE 10-4: OTHER MARINE USERS 10-14FIGURE 11-1: GALIA PRODUCTION WELL IN RELATION TO THE WIDER ALMA DEVELOPMENT 11-2FIGURE B-1- SCENARIO 1-WORST CASE CRUDE OIL SPILL OF 100,000M3 B-7FIGURE B-2-SCENARIO 2- WORSE CASE CRUDE OIL SPILL TRAJECTORY WITH 30 KNOT WIND

TOWARDS THE UK B-8FIGURE B-3-SCENARIO 3- WORSE CASE CRUDE OIL SPILL TRAJECTORY WITH 30 KNOT WIND

TOWARDS THE CLOSEST INTERNATIONAL BOUNDARY (AND DENMARK) B-9FIGURE B-4- SCENARIO 4- INSTANTANEOUS DIESEL SPILL OF 5,830M3 B-10FIGURE B-5- SCENARIO 5- WORST CASE DIESEL SPILL TRAJECTORY WITH 30 KNOT WIND

TOWARDS THE UK B-11FIGURE B-6- SCENARIO 6- WORST CASE DIESEL SPILL TRAJECTORY WITH 30 KNOT WIND

TOWARDS THE CLOSEST INTERNATIONAL BOUNDARY B-12FIGURE D-1: RISK ASSESSMENT FLOW CHART FOR DELIBERATE INJURY D-2FIGURE D-2: RISK ASSESSMENT FLOW CHART FOR NON-TRIVIAL DISTURBANCE D-2FIGURE D-3: M-WEIGHTING FUNCTIONS FOR LOW-, MID-, AND HIGH-FREQUENCY CETACEANS D-3



ACRONYMNS AND UNITS < Less than

> More than A

ACOPS Advisory Committee on Protection of the Sea ALSF Aggregates Levy Sustainability Fund API American Petroleum Institute

B B.P Before Present BAT Best Available Technique bbls Barrels BGS British Geological Society BOP Blow-Out Preventer bopd Barrels of Oil Per Day BS&W Bottom Sediment and Water BSI British Standards Institute bwpd Barrels of Water Per Day

C CBD Convention on Biological Diversity CEFAS Centre for Environment, Fisheries and Aquaculture Science CH4 Methane CMT EnQuest Crisis Management Team CNS Central North Sea CO Carbon Monoxide CO2 Carbon Dioxide CPR Continuous Plankton Recorder

D dB Decibel DECC Department of Energy and Climate Change Defra Department for Environment, Food and Rural Affairs DMRB Design Manual for Roads and Bridges DP Dynamic Positioning DSV Diving Support Vessel DTI Department of Trade and Industry

E EC European Commission EEMS Environmental Emissions Monitoring Scheme EIA Environmental Impact Assessment EMS Environmental Management System EPS European Protected Species ERC Emergency Response Centre ES Environmental Statement ESP Electrical Submersible Pump EU ETS European Union Emissions Trading Scheme

F FAO Food and Agriculture Organisation FDP Field Development Plan FPSO Floating, Production, Storage and Offloading FRS Fisheries Research Service

G GESAMP The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection GGL Gardline Geosurvey Limited GIS Geographical Information Service



H HQ Hazard Quotient HR Conservation (Natural Habitats &c.) Regulations 1994 (as amended) HSE Health and Safety Executive HSEQ Health, Safety, Environmental and Quality Hz Hertz

I IBA Important Bird Areas ICES International Council for the Exploration of the Seas IMT Incident Management Team IPPC Integrated Pollution Prevention and Control Directive ISO International Organization of Standardization

J JNCC Joint Nature Conservation Committee K KISCA Kingfisher Cables

km Kilometre km2 Kilometres squared kPa Kilo Pascal kw Kilo Watt

L LAQM Local Air Quality Management (LAQM) Support. Defra, UK Local Air Quality Management LAT Lowest Astronomical Tide

M gl-1 Microgram per Litre gm-3 Microgram per Cubic Metre Pa Micro Pascal m Metre m2 Metre Squared m3 Cubic Metre MBES Multi-Beam Echo Sounder MCA Maritime and Coastguard Agency MCAA Marine and Coastal Access Act MCZ Marine Conservation Zone MEG Monoethylene Glycol mgl-1 Milligram per Litre mmbbls Million Barrels MMO Marine Mammal Observer MMO Marine Management Organisation MMscf/d Million Standard Cubic Feet per Day MODU Mobile Offshore Drilling Unit ms-1 Metres per Second MW Mega Watt MW(th) Mega Watt (Thermal) MWh Mega Watt Hour

N N2O Nitrous Oxide nm Nautical Miles NNE North-North East NNS Northern North Sea NO2 Nitrogen Dioxide NOEC No Observed Effect Concentration NOx Nitric Oxides

O OBM Oil Based Mud



OCNS Offshore Chemical Notification Scheme OCR Offshore Chemical Regulators OESEA Offshore Energy Strategic Environmental Assessment OGED Oil and Gas Exploration and Development OGUK Oil and Gas UK OIW Oil in Water OMR Offshore Marine Conservation (Natural Habitats &c) Regulations 2007 (as amended in 2010) OPEP Oil Pollution Emergency Plan OPPC Oil Pollution Prevention and Control OSPAR Convention for the Protection of the Marine Environment of the North East Atlantic (Oslo Paris Convention) OSRL Oil Spill Response Limited

P PAH Polycyclic Aromatic Hydrocarbons PAIH Potential Annex I Habitat PEXA Practice and Exercise Areas PIG Pipeline Inspection Gauge PLANC Permits Licenses Approvals Notifications and Consents PLONOR Posing Little or No Risk PLV Pipeline Laying Vessels PM 10 Particles Measuring 10m or less PM 2.5 Particles Measuring 2.5m or less PON Petroleum Operations Notice ppb Parts per billion ppm Parts per million PSA Particle size analysis psia Pounds per Square Inch Atmospheric PW Produced Water PWA Pipelines Works Authorisation PWRI Produced Water Reinjection

Q QMS Quality Management System R REACH Registration, Evaluation, Authorisation and restriction of Chemicals

ROV Remotely Operated Vehicle RYA Royal Yachting Association

S SAC Special Area of Conservation SCANS Small Cetaceans in the European Atlantic and North Sea scfd-1 Standard Cubic Foot per Day SCI Sites of Community Importance SEA Strategic Environmental Assessment SFF Scottish Fishermen's Federation SMRU Sea Mammal Research Unit SNS Southern North Sea SO2 Sulphur Dioxide SoS Secretary of State SOx Oxides of Sulphur SPA Special Protection Area SPL Sound Pressure Levels SSE Scottish and Southern Energy SSS Sidescan Sonar



SSW South-South West SUB Substitution

T THC Total Hydrocarbons U UK United Kingdom

UK BAP UK Biodiversity Action Plan UKCIP UK Climate Impact Programme UKCP United Kingdom Climate Predictions UKCS United Kingdom Continental Shelf UKMMAS UK Marine Monitoring and Assessment Strategy UKOOA United Kingdom Offshore Operators Association (now Oil and Gas UK) UNFCCC United Nations Framework Convention on Climate Change

V VHF Very High Frequency VOC Volatile Organic Compounds

W WBM Water Based Mud WLCDF Well Life-Cycle Decision Framework



GLOSSARY A Air Gun Source of seismic energy used in acquisition of marine seismic data. This gun releases highly

compressed air into water.

Analogue Survey e.g., bathymetry, sonar imagery and shallow profiling. Technique of representing a sensor's input as amplitude modulated electrical signal (e.g., analogue profiles are output on sweep recorders as opposed to digital).

Anode Positive electrode.

Appraisal Well Phase of petroleum operations that immediately follows successful exploratory drilling. Appraisal wells might be drilled to determine the size of the oil or gas field and how to develop it most efficiently.

Aspect (environmental) Element of an organisations activities, products or services that can interact with the environment.

B Backfill The replacement of excavated sediment into a trench. Bathymetry The measurement of the depth of the ocean floor from the water surface; the oceanic equivalent of

topography.

Beaufort Force Empirical measure (scale of 0 to 12) for describing wind velocity based mainly on observed sea conditions established by Admiral Francis Beaufort (1774 to 1857).

Benthic Pertaining to the environment and conditions of organisms living at the bottom of the sea.

Biogenic Chemicals or material produced by living organisms or biological processes.

Blow-out Uncontrolled flow of reservoir fluids into the wellbore, and sometimes catastrophically to the surface. A blow-out may consist of salt water, oil, gas or a mixture of these.

Blow-out Preventer (BOP)

A large valve at the top of a well that may be closed if the drilling crew loses control of the pressure within the well.

C Catch Per Unit Effort (CPUE)

Measurement of the mass of fish caught for a given amount of energy and resources expended by a fishing fleet.

Conductor Casing string that is usually put in to the wellbore at the surface to stop the sides of the well falling in.

Cone Penetrometer Test (CPT)

Method of providing data for use in characterising subsurface marine sediments consisting of a steel cone that is hydraulically pushed into the ground. Sensors on the tip of the cone collect data to classify sediment type by measuring cone-tip pressure and friction.

Cuttings Small pieces of rock that break away due to the action of the bit teeth. Cuttings are screened out of the liquid mud system at the shale shakers and are monitored for composition, size, shape, colour, texture, hydrocarbon content and other properties.

D Demersal Organisms dwelling at or near the bottom of the sea. Development The phase of petroleum operations that occurs after exploration has proven successful, and before

full-scale production. The newly discovered oil or gas field is assessed during an appraisal phase, a plan to fully and efficiently exploit it is created, and additional wells are usually drilled.

Downhole In a well bore. E Echolocation Used by animals to orientate, navigate, and find food it is the detection of the position, distance and

size of an object by means of reflected sound.

Echosounding The action or process of sounding or ascertaining the depth of water or of an object below a ship by measuring the time taken for a transmitted sound-signal to return as an echo.

Effort Measure of input extended by people to catch fish (expressed in days fished). Environmental Impact

Assessment (EIA) The critical appraisal of the likely effects of a proposed project, activity, or policy on the environment, both positive and negative.



Environmental Statement (ES)

A means of submitting to the regulatory authority, statutory consultees, non-government organisations and the wider public, the findings of an EIA.

Epifauna Organisms living on the seabed surface. Epilithic Organisms growing attached to an inorganic substratum, such as rocks, stones, etc. F Flaring The burning of unwanted gas through a pipe. Flaring is a means of disposal used when there is no

way to transport the gas to market and the operator cannot use the gas for another purpose.

G Geohazard Any geological or hydrological process that poses a threat to people and/or their property. Geophysical The study of the earth by quantitative physical methods, especially by seismic reflection and

refraction, gravity, magnetic, electrical, electromagnetic, and radioactivity methods.

Geotechnical The study of soil and rock below the ground to determine its properties. Grey Water Non-industrial wastewater generated from domestic processes such as washing dishes, laundry

and bathing.

H Hydrotest The process of pumping water through a pipeline at a higher pressure level than is normally used when transporting petroleum to confirm the continued safe operation of the pipeline, ensuring that it's free of any defects.

I ICES rectangles Statistical divisions of the sea. Impact (environmental) Any change to the environment, whether adverse or beneficial, wholly or partially resulting from an

organisation's activities, products or services.

Infauna Organisms that live within the sediment. K Kingfisher Bulletins Fortnightly bulletin providing free safety information to all sea users. Kilometre Point (KP) A general term for the distance along a route from a fixed reference point. L Lowest Astronomical

Tide (LAT) The lowest level that can be expected to occur under average meteorological conditions and under any combination of astronomical conditions.

M Macrofauna Benthic animals larger than 1 mm in size and include the large polychaete worms, corals, shellfish, and starfish.

Magnetometer An instrument for measuring the strength of a magnetic field. MARPOL Convention International Convention for the Prevention of Pollution from Ships (1973/1978). Median Line Offshore international boundary. Mobile Offshore Drilling

Unit (MoDU) A generic term for several classes of self-contained floatable or floating drilling machines such as jack-ups, and semi-submersibles.

Multivariate Describes a collection of procedures which involve observation and analysis of two or more statistical variables at a time.

N North Atlantic Oscillation

A climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores high.

Notices to Mariners Information issued from a number of different sources, such as the UK Hydrographic Office, Trinity House or Local Harbour Authorities and may contain a variety of information such as chart updates, changes in buoyage, prior warning of activities such as dredging, exclusion zones, etc.

O Oil Producer A well producing oil. OSPAR Instrument guiding international cooperation on the protection of the marine environment of the

North-East Atlantic.

P Pelagic Relating to or occurring or living in or frequenting the open ocean. Petrogenic A contaminant produced from unburned petroleum products.

Phytoplankton Microscopic floating plants that exist within the water column.



Phytoplankton Bloom

High concentration of phytoplankton in an area, caused by increased reproduction.

Pinger Seismic source.

Platform An offshore structure that is permanently fixed to the seabed used to house workers and machinery needed to drill and then produce oil and natural gas in the ocean.

Plugged and Abandoned

To prepare a well to be closed permanently with cement plugs and salvage all recoverable equipment, usually after either logs determine there is insufficient hydrocarbon potential to complete the well, or after production operations have drained the reservoir.

Potential Annex I Habitat (PAIH)

Habitat (as defined in Annex I of the EC Habitats Directive) identified in offshore areas to be put forward to the government for protection as part of the Natura 2000 in UK offshore waters programme.

Produced Water (PW) Formation water (naturally occurring layer of water in oil and gas reservoirs) and injected water that is produced along with hydrocarbons. At the surface, the water is separated from the hydrocarbons, treated to remove as much of the hydrocarbons as possible and discharged into the sea or injected back into wells.

R Ramsar Site Wetland of international importance designated under the Ramsar Convention (1971). Receptor

(environmental) Element of the environment that an environmental aspect can interact with or impact.

Re-injection (produced water)

Method of enhanced oil recovery to compensate for the natural decline of an oil field production by increasing the pressure in the reservoir. Produced water is injected to maintain reservoir pressure and hydraulically drive oil toward a producing well.

Reservoir Subsurface body of rock having sufficient porosity and permeability to store and transmit fluids

Rig A drilling unit that is not permanently fixed to the seabed, e.g., a drillship, a semi-submersible or a jack-up unit. Also means the derrick and its associated machinery.

Riser The pipe which connects a rig or platform to a subsea wellhead or subsea pipeline during drilling or production operations to take mud returns to the surface; or the pipe which connects a pipeline to a platform.

S Seismic Pertaining to waves of elastic energy, such as that transmitted by P-waves and S-waves, in the frequency range of approximately 1 to 100 Hz, used to interpret the composition, fluid content, extent and geometry of rocks in the subsurface.

Semi-Diurnal Occurring once every 12 hours. Semi-Submersible Rig Floating vessel that can be used for drilling supported primarily on large pontoon-like structures

submerged below the sea surface usually anchored with six to twelve anchors.

Shellfish An aquatic animal, such as a mollusc or crustacean, which has a shell or shell-like exoskeleton. Side-Scan Sonar (SSS) Sonar device used for mapping the seabed. Spawning Reproductive activity of fish; the act of releasing eggs into the water by female fish for fertilisation by

male fish.

Species A group of related organisms having common characteristics and capable of interbreeding. Stochastic Model A model involving or containing a random variable or variables; involving chance or probability. Subsea Situated or occurring underwater. Subsea Control System Subsea system that provides electro/hydraulic control of subsea and downhole hydraulically

operated valves. It also provides a data link to the platform control system conveying subsea/downhole operating parameters and performance.

Subsea Control Umbilical

Connects remotely positioned subsea satellite production and/or injection trees to subsea template controls or to surface controls on a platform. An umbilical can include up to eighteen separate control hoses within a casing e.g., hydraulic hoses, chemical injection hoses and electrical cables.

Suspended (well) A well that has been capped-off temporarily.



T Taxa Categories in the biological classification system for all living organisms (i.e., kingdom, phylum, class, order, family, genus, species).

Thermocline The vertical zone in the water column where temperature changes rapidly with depth.

Tie-in An operation in pipeline construction in which two sections of line are connected; a loop tied into the main line.

Topside The superstructure of a platform. U Umbilical A conduit through which hydraulic fluids, chemicals, power and data are supplied (see subsea

control umbilical).

Univariate Describes a collection of procedures which involve observation and analysis of one statistical variable.

V Vibrocore Acquisition of seabed sediment cores using a vibrating steel tube which penetrates the seabed to a particular depth.

W Water Injector A well in which filtered and treated seawater is injected into a lower water-bearing section of the reservoir, the primary objective typically being to maintain reservoir pressure.

Well Head The surface termination of a wellbore that incorporates facilities for installing casing hangers during the well construction phase. The wellhead also incorporates a means of hanging the production tubing and installing the Christmas tree and surface flow-control facilities in preparation for the production phase of the well.

Well-Test A test whereby the nature and quantity of the formation fluids in a possible oil- or gas-bearing stratum are determined by allowing them to flow to the surface through the drill string under carefully controlled conditions.

X Xmas Tree An array of pipes and valves fitted to a production wellhead to control the flow of oil or gas and prevent a possible blow-out.

Z Zooplankton Small aquatic animals that float or weakly swim within the water column. Generally longer than 153 m, up to about 5,000 m (5 mm).


REPORT REF: P1459BA_RN2525_REV0 1-1 21/07/2011

1 INTRODUCTION

EnQuest Heather Limited wishes to redevelop the Ardmore field in the UK Central North Sea (CNS). The field, to be renamed Alma, will be developed through two drill centres tied-back via new oil production and water injection flowlines to a floating production, offloading and storage facility (FPSO).

This Environmental Statement (ES) has been prepared on behalf of EnQuest to meet the requirements of United Kingdom (UK) legislation and in support of their field development plan. It covers:

Drilling of six production wells and two water-injection wells

Installation of two 10-inch production flowlines, one 10-inch water-injection flowline, two control umbilicals and one power cable

Installation of the Uisge Gorm Floating, Production, Storage and Offloading (FPSO) facility

Export of crude oil via shuttle tanker

Operation and production of the field for an expected 10 years

1.1 THE DEVELOPER

EnQuest Heather Limited is an independent oil and gas production and development company with a geographic focus on the UK continental shelf (UKCS). The Groups asset portfolio comprises primarily producing assets and development opportunities, together with exploration and appraisal opportunities, all of which are located in the UKCS. It has working interests in the Don, Thistle, Deveron, Heather, Ivy and Broom oil fields.

EnQuest believes that the UKCS represents a significant hydrocarbon basin in a low-risk region. The UKCS continues to benefit from an extensive installed infrastructure base and skilled labour to develop, operate and manage assets. EnQuests management has considerable experience of working in the UKCS region and is familiar with the regulatory authorities and competitive landscape.

EnQuest Heather Limited owns a 100% stake of the equity of the Alma Field.

1.2 PROJECT OVERVIEW

As a redevelopment of the Ardmore field, the Alma field will be a small oil development with a field life of ten years. The field is located in UKCS Blocks 30/24 and 30/25, 274km east of the nearest landfall on the Northumberland coastline in the CNS. It is approximately 18.5km from the Norway/UK international boundary (median line). The project location is shown in Figure 1-1 and the co-ordinates are given in Table 1-1.

AAA

A

AA

AAAA

AAA

A

AAAAAAA

AA

AAAAAAAAAAAAAAAAA

A

A

A

AAA

A

A

A A

A

A

AAA

A

A

A

A

A

AAA

A

AA

A

AAA

A

A

A

AA

A

A

A

A

A

A

A

AA

A

A

AA

A AA

A

A

AAAAAAA

AA

A

AA

AA

A

A

A

AAA

AAA

A

AAAAAAAAAAA

AAA

A

A

A

AAA

A

AA

A

A

A

A

A

A

A

A

A

A

A

AA

A

A

A

AAAAAA

A

A

A

AA

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

AA

AAAA

AAAAA

A

A

A

AAAAA

A

A

A

A

A

A

A

A

A

A

A

AAA

A

AA

AAAA

AA A

A

AA

A

AAAAAAA

AAA

A

AAAAAAA

A

AAAA

A

AAAAAAAAAAAA

AAA

A

A

AA

AA

A

A A

AA

A

AA

A

AAA

A

A

A

AAAAAAAA

AA

A

A

AAAAA

A

A

A

A

A

A

A

AAA

A

AA

A

A

A

A

A

A

A

A

A

AAA

A

A

AA

AA

AA

A

AAA

A

AA

AA

A AA

AA

A

AAAA

AAAAAAAAAAAAAAAAAA

AAA

A

A

A

AA

A

AA

A

AAA AAAAAAAAAA

A

AA

AAAAA

AAA

AAAA

A

A

A

A

A

AAA

AAAAA

AAA

AA

A

A

A

A

A

A

A

AA

A

AAAA

AAA

AAAAAAAAA

AA

A

A

A

AAAAAA

A

A

A

AAA

A

AA

A

A

A

A

AAA

A

A

A

AAAAAA

AA

AAA

AAAAAAAAAAAA

AAAAAAA

A

A

A

A

A

A

A

AAAAA

AA

AAAAAAAAA

AA

A

A

AA

AAA

A

AAA

AA

A

AAAAA

A

A

A

A

AA

A

A

A

A

A

A

AA

AA

A

A

A

A

A

A

A

")

")

")

")

")

")

")

")

XW

XW!.

!.

320'E

320'E

240'E

240'E

20'E

20'E56

40'N

5640'N

5615'N

5615'N

5550'N

5550'N

.

Alma Field Development Environmental StatementFigure 1-1: Project Location

NOTE: Not to be used for navigation

Produced ByReviewed By

Louise MannAnna Farley

Wednesday, July 6, 2011 15:10:52ED 1950 UTM Zone 31N

D European 1950EnQuest, UKDeal, KISCAJ:\P1459\Mxd\Environmental Statement\.mxdFigure 1-1 Project Location

International 1924

Metoc Ltd, 2011.

DateProjection

DatumData SourceFile Reference

Spheroid

Checked

All rights reserved.0 8 16 24 32 404 km

LegendMedian lineLandUKCS Block

XW Uisge Gorm FPSO!. Northern Drill Centre!. Southern Drill Centre

Production FlowlineWI Flowline

XW FPSO") PlatformA Well

PipelineCableHydrocarbon Field

A

A

A

AA

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

A

AA

A

A

A

A

A

A

A XW

!.

!.Block 30/25

Block 30/24

0 0.8 1.6 2.4 3.20.4Kilometers

Southern Drill Centre

Uisge Gorm FPSO

Northern Drill Centre

Janice Alpha



Table 1-1: Project co-ordinates Structure Easting (E) Northing (N) Latitude (N) Longitude (E) Uisge Gorm FPSO 488 250 6 227 000 56 11' 16.16" 02 48' 38.45" Northern drill centre (production wells) 485 469 6 228 541 56 12' 05.72" 02 45' 56.84" Southern drill centre (water-injection wells) 485 858 6 224 891 56 10' 07.71" 02 46' 20.12"

Datum: WGS84

1.2.1 Field History

The Argyll field was discovered in 1971 and brought on stream as the UKs first oilfield by the Hamilton Brothers. The Field was decommissioned in 1992 due to the low oil price prevalent at the time. Between 1975 and 1992 Argyll produced 74.8 mmbbl (million barrels) oil. The final field rate was 5,000 bopd (barrels oil per day) with a 70% water cut.

The Argyll Field was renamed Ardmore and redeveloped by Tuscan and Acorn, with second phase first oil in 2003. Between 2003 and 2005 Ardmore produced a further 5.2 mmbbl oil. The field was the decommissioned again in 2008 because of low profitability.

EnQuest now plan to rename and redevelop the Ardmore field as Alma as it is now commercially viable to develop from a small marginal field due to the prevailing oil price. As the entire previous field infrastructure was removed during the Ardmore decommissioning, and as Alma is a marginal field and production will likely be short-term, EnQuest are proposing to use an FPSO rather than install a platform.

The Field consists of three main productive intervals, namely Zechstein carbonates and evaporates, Rotliegend Aeolian sandstone and Devonian sandstone/siltstone. It is located on a large Palaeozoic, southwest to northeast trending tilted fault block on the south-western flank of the Central Graben. The Field structure measures approximately 2.5km wide and 6km long.

1.2.2 Schedule

Construction is scheduled to start in January 2012 with the drilling of the first production well. Construction activities will continue through to May 2013 with first oil expected in third quarter 2013. A total of six production wells and two water injector wells will be batch drilled and are expected to take approximately three months each to drill and complete. Field life is anticipated to be ten years.

1.2.3 Construction

The Alma field development will consist of eight wells; six oil producers and two water-injectors. The water injectors will be drilled from a southern drill centre and the production wells from a northern drill centre. All wells will be tied-back via new flexible flowlines to the Uisge Gorm FPSO.

Flowlines will consist of one 10-inch water-injection flowline to the southern drill centre and two 10-inch production flowlines to the northern drill centre. As a general rule the water injection flowline will be trenched and backfilled where possible. In the event of any undulations in the trench (and subsequently the flowline) a contingency will be in place for the provision of approximately 5,000



tonnes of rock for deposition for protection. The rock will be deployed to mitigate any upheaval buckling (low risk for flexible flowlines) or pipeline out of straightness events experienced during the trenching and pipe-lay activities. This may be required for pipeline protection, depth of cover anomalies or dropped object protection. The requirement for rock deposition will be identified during post lay survey and if required the rock will be placed accurately using a dynamically positioned installation vessel. The vessel will be equipped with a fall pipe to deploy rock accurately in the spot location. Due to the infield debris (both buried and on the seabed), wellheads and the associated infrastructure in place from previous field operations, it is difficult to establish a clear route and therefore it will not always be possible to trench and backfill the flowline. Where it is not possible to trench, the line will be surface-laid and protected by concrete mattresses and grout bags. The use of trenching and backfilling will be optimised and surface laid pipe minimised. The production flowlines cannot be trenched and backfilled as this would result in high arrival temperatures of the production fluids at the FPSO. The flowlines will instead be surface laid and protected by concrete mattresses and rock material where required.

Production wells will be fitted with electrical submersible pumps (ESPs) to assist flow rates. The wells will be drilled from a semi-submersible drilling rig. Drilling is expected to commence in January 2012, with the rig remaining on site until April 2013.

The production flowlines will terminate in a manifold at the northern drill centre and in a bolted straight T piece to the flexible risers beneath the FPSO. This T piece will allow for future tie-ins. The risers will then connect to the FPSO in a lazy S configuration. In addition a control umbilical will be surface laid out to each drill centre and a power cable will also be laid out to the production wells. The flowline corridor will be approximately 30m wide to the southern drill centre and 50m wide to the northern drill centre. Each riser will be held in place with a vertical and horizontal hold-back tether. Each hold-back tether will consist of one upper piled or gravity riser base (vertical) and one lower clump weight holdback anchor (horizontal) (Figure 1-2).

Figure 1-2: FPSO riser hold-back tether example

Note: Image is for illustrative purposes only and does not necessarily reflect exact layout of flowlines and associated infrastructure.



It is possible that the flowlines will require dropped object protection around the well head areas. This will take the

alma field development environmental statement

Documents