Environmental impact assessment – Pipeline and wells

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ÆRFUGL PHASE 1

Environmental impact

assessment – Pipeline and wells

Aker BP ASA

Report No.: 2019-0081, Rev. 00 Document No.: 1177E74O-10 Date: 2019-01-30

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1 EXECUTIVE SUMMARY

On behalf of Aker BP, DNV GL has conducted an environmental impact assessment for the planned pipeline and drilling operations at the Ærfugl development (Phase 1).

The assessment focuses on the documented corals surveyed along the route, gathered from several surveys and combined in an environmental resource map.

The potential impacts on corals assessed in this report are the following:

1. The well locations (Well 4, 5 & 6) 2. The pipeline and umbilical routes.

1.1 Conclusions

Impact from drilling

The only corals found within the influence area of the drilling locations was two single Paragorgia arborea 295m south of well 4, so impact from drill discharges is limited. The wells will be drilled with a DP rig, thus there is no present risk from anchor chains.

Impact from pipeline

The pipeline laying operation is governed by Subsea7 and the route is designed to cause as little effect on the surrounding corals as operationally possible.

In conclusion the impact on the close by corals will be limited but present. The planned pipeline will cross two coral structures and one structure will be covered by rock dumping. The umbilicals will cross three structures. In total 17 structures are closer than 15 meters of the planned installation. The umbilical routing is more flexible, thus coral damage can be avoided by laying the cables around know coral structures. An overview of the closest corals is shown in the table below.

Table 1-1 Corals structures within 15m of the pipeline, umbilicals and rock dumping , respectively.

Structures marked red will be crossed and most likely damaged by the planned route. “Fauna combined”

colour is based on the coral value (see Table 2-4).

Structure Lophelia Coral garden Lophelia value Paragorgia value Fauna combined X ED50UTM32N Y ED50UTM32N Shape Area Distance from Pipeline Distance from Pipeline Service Umbilical Distance EHTF flow line Distance URB3-W4 Distance from rock dumping

ENV7 Dead/poor Single 2 1 3 437675 7291657 124 12 2 ENV8 Dead/poor Single 2 1 3 437596 7291673 1479 11 1 ENV11 Dead/poor Common 2 3 5 437541 7291626 259 crossing

12

crossing 6

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54 Dead Poor 1 1 2 437013 7291526 53 18 8 10

41 Poor Poor 2 1 3 435899 7290682 37 16 6 8

40 Poor Poor 2 1 3 435897 7290671 134 6 crossing

9

1

39 Poor Poor 2 1 3 435883 7290663 28 17 7

22 Dead Poor 1 1 2 435243 7290047 32 6 crossing

6

15 Dead Poor 1 1 2 434443 7289283 34 0,1 4 Cove

red Skarv

BC2-2

Poor Fair 2 2 4 434425 7289262 28 crossing 5 6

5 Poor Poor 2 1 3 434320 7289153 18 5 15

ENV84 Poor Single 2 1 3 432613 7285268 48 2 0,3

2032 Dead Poor 1 1 2 434028 7284691 86 10

2034 Poor Fair 2 2 4 434205 7284731 234 5

2056 Good Fair 4 2 6 434132 7284750 179 13

2046 Poor Good 2 3 5 438409 7286072 84 2,

5

2049 Poor Excellent 2 4 6 435604 7286858 454 9

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Figure 2-1 An overview of the area, with the closest fields Idun and Skarv

2 INTRODUCTION

Aker BP is together with Subsea7 planning to develop a subsea installation – Ærfugl, in block 6507/5. In phase 1, 3 wells (well 4,5 & 6) are planned and will be connected with a pipeline to the Skarv FPSO.

The field is located in an area with cold water corals and DNV GL have been aiding in mapping and assessing the sensitive fauna in order to minimize the environmental footprint of the development.

Several extensive surveys have been conducted and this document serves as a summary of the relevant

environmental surveys to date. Further, an impact assessment based on the given survey data is presented.

2.1 Previous studies and surveys

In the Ærfugl / Skarv/ Idun area several benthic surveys have been conducted and from the gathered survey data, a GIS environmental resource map have been created for the Ærfugl project and have been continuously updated following the changes of the pipeline route.

Table 2-1 Visual and bathymetric surveys conducted at Ærfugl.

Date Document Provider Description

12.08.2016 ENVIRONMENTAL FIELD

REPORT

NO.E10503.RE.16.089

Deepocean, Gardline Extended site survey

19.05.2017 Coral targets at Snadd – Memo 2017-05-19

DNV GL A summary of the

present corals at Ærfugl, based on previous surveys.

21.11.2017 Skarv – Visual Survey of Corals along Snadd Pipeline SKASO-P0031- DOG-O-RA-0050

Deepocean Additional survey along new pipeline route

26.03.2018 Visual assessment of video and coral interpretations. Memo 1177E74O-1/ LUVES

DNV GL Coral assessment of

the Deepocean survey November 2017.

06.07.2018 VISUAL MAPPING AT

ÆRFUGL - Environmental survey report Document No.: 180843

Deepocean, DNV GL Additional survey along umbilical routes and well locations

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Focus in this document is the reef building coral – Lophelia pertusa and soft, non-reef building corals, mainly the gorgonian Paragorgia arborea. Classifications criteria as described in the NOROG guideline;

Monitoring of drilling activities in areas with presence of cold water corals (2013), are shown in Table 2-2 below.

Table 2-2 Criteria for coral conditions.

2.2 Resource map 2.2.1 Methodology

From the bathymetry and video data gathered during the site surveys, polygons delineating the assessed reef structures were created. Potential coral areas not visually surveyed were classified as DD (data deficient). Each reef polygon was given a value for Lophelia condition and Coral garden value as shown in Figure 2-2 and for the impact assessment the combined coral value for each polygon was classified as described in Table 2-4.

Figure 2-2 Left; visual survey of potential coral targets. Right; Coral polygons with combined coral value.

Table 2-3 Classification value of corals for assessment purposes.

Value 1 2 3 4 5 66

Lophelia reef

Dead Poor Fair Good Excellent Data

deficient Coral

garden

Poor

(>5/25m²)

Fair

(>5-10/25m²)

Good

(>10-15/25m²)

Excellent

(<15/25m²)

Data deficient

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Table 2-4 Classification of combined coral values

Condition Dead/Poor Moderate/Poor Good/Moderate Excellent/Good DD

(Data deficient) Combined

Value

1-2 3 4 5-9 11

3 AREA DESCRIPTION

3.1 Seafloor characteristics

The Ærfugl development is located on the Haltenbank at depth ranging from 320 meters at in north east to 420 meters at well 6 in south west. The seafloor is characterized by, scour marks, ridges and furrows in the north and flatter, mud sand sediments with occasional boulders and mounds in the deeper south.

3.2 Sponges

Sponges are present at Ærfugl in scattered to common densities and dominantly hardbottom associated species. Softbottom associated species were found in only single to scattered densities and never in high enough numbers to be classified as “Deep sea sponge aggregations” protected by OSPAR (2010).

3.3 Corals

3.3.1 Lophelia reefs

From 89 investigated potential coral targets 62 were found to house living Lophelia pertusa. Lophelia reefs are present mainly in the northern part of the

development area, closest to the Skarv FPSO. The reef condition is manly poor with few living polyps and traces from fishing activities are present with trawl marks, damaged corals and entangled fishing equipment (Figure 3-2). An overview of the coral condition is shown in Figure 3-1.

Figure 3-1 Distribution of coral condition on the logged corals at Ærfugl.

Lophelia condition

Nr. of structures

% of structures

Not present 8 7.5

Dead 19 17.8

Poor 36 33.6

Fair 19 17.8

Good 6 5.6

Excellent 1 0.9

Not surveyed

(DD) 18

16.8

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Figure 3-2 Left; fishing equipment entangled in a Lophelia reef. Right; a Lophelia reef in partly good condition but with an entangled net on the backside.

3.3.2 Coral gardens

Gorgonian corals, mainly of the species Paragorgia arborea, are found scattered across the entire area, mainly as single colonies in boulder areas. A percentage of boulder areas with corals present along the old pipeline route is shown in Table 3-1 below. On the Lophelia reefs bigger aggregations could be found classifying as OSPAR coral gardens.

Table 3-1 Distribution of surveyed boulders with/ without single Paragorgia arborea.

Pipeline

route Well 4 Well 5 Well 6 Total Investigated boulder

areas 456 16 30 12 514

Paragorgia present 104 5 12 1 122

% of areas with

Paragorgia 23 31 40 8 24

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Figure 4-1 Modelled drill discharges at well 6.

Figure 3-3 Left; investigated point targets with and without corals. Right; Target 2049, a dead Lophelia reef covered with corals Paragorgia arborea and Primnoa resedaeformis and the giant file clam; Acesta excavata.

4 ENVIRONMENTAL IMPACT

At Ærfugl, the environmental focus has been to minimize the effects on the cold-water corals and the main potential risks comes from:

- Drilling of wells - Pipeline

- Rock dumping - Umbilical’s

4.1 Well locations 4.1.1 Discharge areas

The discharge areas have been thoroughly investigated with MBES, SSS and with ROV. Only two smaller potential coral areas were discovered from MBES/SSS (target 2052 and ENV54) at well 4. During the visual survey only one of these targets (2052) was found to house any corals; a few single Paragorgia arborea. Impact on these is considered small. Drill particle discharges were modelled for the old well locations using Seafan and show a slightly northern current regime with typical dispersion of drilling discharges. Discharge

sedimentation rate above 10 mm is expected furthest out to 100m from PWL, 3-10mm out to approx. 250m and 1-3mm to approx. 500m.

4.1.2 Anchors

Anchor chain lines can cause physical damage on sensitive

fauna along the seabed. However, at Ærfugl it is planned to drill the wells with DP rig without anchors, so no risk of damage from anchors is present.

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4.2 Pipeline

The Ærfugl pipeline is approx. 20,5 km long and planned to be laid on the seabed without any benthic interfering equipment like trenching or jetting and with the use of a DP vessel. Thus, the source of seafloor impact is limited to the pipeline itself. Based on experience from previous similar pipeline operations (DNV GL, 2014) the impact area is limited to directly beneath the pipe (~0.5 m) and a small area with stirred up sediments, giving at total impact width of approx. 1 meter.

Figure 4-2 A example of a pipeline with a small visual impact on the benthic fauna.

However, buckling of hot pipelines can cause lateral movements, potentially causing damage to adjacent sessile fauna like corals. At Ærfugl an RCM (Residual Curvature Method) will be used, which means that pipeline buckling will be limited to specific controlled areas, thus damage to corals can be avoided/

reduced.

Risk of damage to corals caused by re-suspended sediment is low as sediment resuspension is only caused during “touchdown” of the pipe which is expected to cause a small plume of sediment in a limited period of time. Corals (Lophelia pertusa) have been shown to tolerate being exposed to high

concentrations of natural sediments during shorter periods (~24h) (Brooke et. Al, 2009 & Allers et al.,2013).

Using the latest pipeline route (dated 21.03.2018), two coral areas will be crossed by the pipeline;

ENV11 & Skarv BC2-2. Given an estimated impact width of 1 meter, the pipeline will have an impact of respectively 5 and 18 percent on the two coral areas, as described in Table 4-1. In total nine coral structures are closer than 15 meters from the pipeline route and considered within risk. An overview of the corals is presented in Table 4-2.

Table 4-1 Table over the two structures that are crossed by the pipeline and the anticipated impact area.

Structure Shape Area Crossing pipeline impact

area (m²) Damaged area (%)

ENV11 259 12 5

Skarv BC2-2 28 5 18

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Table 4-2 Distance to the nearest coral structures from the Pipeline. “Fauna combined” colour is based on the coral value (see Table 2-4).

Structure Lophelia Coral

garden Fauna

combined Shape Area X ED50

UTM32N Y ED50 UTM32N

Distance from Pipeline

ENV7 Dead/poor Single 3 124 437675 7291657 12

ENV8 Dead/poor Single 3 1479 437596 7291673 11

40 Poor Poor 3 134 435897 7290671 6

22 Dead Poor 2 32 435243 7290047 6

5 Poor Poor 3 18 434320 7289153 5

ENV84 Poor Single 3 48 432613 7285268 2

15 Dead Poor 2 34 434443 7289283 0,1

ENV11 Dead/poor Common 5 259 437541 7291626 crossing

Skarv BC2-2 Poor Fair 4 28 434425 7289262 crossing

4.2.1 Rock dumping

The second largest benthic footprint comes from rock dumping, which will be used in counter fills, crossings and locking of the pipeline. Rock dumping results in direct removal of habitats usually in 5-15 meters wide corridors but can reach further depending on seabed topography and technical solutions.

The effects from resuspension of sediments during rock dumping is depending on laying technique, seafloor characteristics and rock size and generally causes a transition area outside the rock dumping area, with moderate impact on the seabed communities, typically <5m.

Along the route, 26 rock dumping areas have been planned, covering in total 9065 m²of seafloor. One coral structure (Structure 15, in poor condition) will be largely (70%) covered by rocks (Figure 4-3) and

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further, 4 structures are within 15 meters of the rock dumping site and are described below in

Figure 4-3 Coral structure 15, that will be largely covered by rock.

Table 4-3 Table over the coral structures that are closer than 15m from a rock site. Structure colour is based on combined coral value (see Table 2-4).

Corals structure Rock dumping area

(m2) KP Distance to rock area

15 270 15.57 0, covering 70% of coral structure

Skarv BC 2-1 270 15.57 15 m

40 330 17.60 1 m

41 330 17.60 8 m

54 210 18.97 11 m

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Figure 4-4 The umbilical routes.

Figure 4-3 Coral structure 15, that will be largely covered by rock.

4.2.2 Umbilical routes

The Ærfugl development is powered by 3 umbilical cables; a service cable along the pipeline, a service umbilical from Skarv FPSO to well 4 and a power cable for the EFTF pipeline as shown in Figure 4-4.

Potential impact form the umbilicals is small as they are light and flexible and routes can be planned avoiding coral targets. However streching the cable can cause it to drag along the seafloor, getting snagged in corals. With the current design the umbilicals crosses over 3 coral structures and is within 15m of 14 further structures (Table 4-4).

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Table 4-4 Distance to the nearest coral structures from the umbilicals “Structure” colour is based on the combined coral value (see Table 2-4).

Structure Shape

Area X ED50

UTM32N Y ED50

UTM32N Distance from Pipeline Service

Umbilical

Distance EHTF flow

line

Distance URB3- W4

ENV7 124 437675 7291657 2 m

ENV8 1479 437596 7291673 1 m

ENV11 259 437541 7291626 Crossing

54 53 437013 7291526 8 m

41 37 435899 7290682 6

40 134 435897 7290671 Crossing

39 28 435883 7290663 7 m

22 32 435243 7290047 Crossing

15 34 434443 7289283 4 m

Skarv BC2-

2 28 434425 7289262 6 m

5 18 434320 7289153 15 m

ENV84 48 432613 7285268 0.3 m

2032 86 434028 7284691 10 m

2034 234 434205 7284731 5 m

2056 179 434132 7284750 13 m

2046 84 438409 7286072 2.5 m

2049 454 435604 7286858 9 m

5 CONCLUTIONS

Corals are found mainly in the northern part of the pipeline route and the impact on corals from the pipeline and well development at the Ærfugl Phase 1 development is limited. Two coral structures will be crossed by the pipeline, one will be partly covered by the rock dumping operation and three coral structures will be crossed by the planned umbilical route. The likely impacted corals and structures within risk of damage are presented in Table 5-1 below.

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Table 5-1 Corals structures within 15m of the pipeline, umbilicals and rock dumping , respectively.

Structures marked red will be crossed and most likely damaged by the planned route. “Fauna combined”

colour is based on the coral value (see Table 2-4).

Structure Lophelia Coral garden Lophelia value Paragorgia value Fauna combined X ED50UTM32N Y ED50UTM32N Shape Area (m2) Distance from Pipeline (m) Distance from Pipeline Service Umbilical (m) Distance EHTF flow line (m) Distance URB3-W4 (m) Distance from rock dumping (m)

ENV7 Dead/poor Single 2 1 3 437675 7291657 124 12 2

ENV8 Dead/poor Single 2 1 3 437596 7291673 1479 11 1

ENV11 Dead/poor Common 2 3 5 437541 7291626 259 crossing 12 crossing 6

54 Dead Poor 1 1 2 437013 7291526 53 18 8 10

41 Poor Poor 2 1 3 435899 7290682 37 16 6 8

40 Poor Poor 2 1 3 435897 7290671 134 6 crossing 9 1

39 Poor Poor 2 1 3 435883 7290663 28 17 7

22 Dead Poor 1 1 2 435243 7290047 32 6 crossing 6

15 Dead Poor 1 1 2 434443 7289283 34 0.1 4 Covered

Skarv BC2-2

Poor Fair 2 2 4 434425 7289262 28 crossing 5 6

5 Poor Poor 2 1 3 434320 7289153 18 5 15

ENV84 Poor Single 2 1 3 432613 7285268 48 2 0.3

2032 Dead Poor 1 1 2 434028 7284691 86 10

2034 Poor Fair 2 2 4 434205 7284731 234 5

2056 Good Fair 4 2 6 434132 7284750 179 13

2046 Poor Good 2 3 5 438409 7286072 84 2.5

2049 Poor Excellent 2 4 6 435604 7286858 454 9

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6 MITIGATING MEASURES AND MONITORING 6.1 MITIGATING MEASURES

The route has been planned with focus on minimal environmental impact, thus the most important mitigating measures have already been performed. However, several actions can be taken to further reduce the risk of damaging close by corals:

Pipeline route

• Accuracy when laying is of high importance. Visually observing the operation with ROV may reduce risk and can document potential impact.

• Planning the pipeline buckling areas to reduce the risks from temperature induced lateral movements.

Rock dumping

• Again, accuracy when laying is crucial. Rock operators to be informed and aware of the coral targets.

• Minimising the resuspension of sediments by dumping the rocks as close to the seafloor as possible using e.g. a fall pipe vessel.

• Visual and /or acoustic aids when laying.

Umbilicals

• As the umbilicals is more flexible than the pipleine it is possible to route the cables avoiding the coral structures, hence when laying this should be communicated and performed.

• To further reduce the risk of damaging corals, the umbilicals should be laid with ROV supervison.

6.2 Monitoring

Visual documentation of potential damages caused by the pipeline laying operation should be performed after laying, this could suitably be conducted during e.g. a post laying survey or pipe inspection. Follow up surveys, studying long term effects could also be performed to gain knowledge about effects on corals from pipeline operations.

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7 REFERENCES

Allers, E., R. M. M. Abed, L. M. Wehrmann, T. Wang, A. I. Larsson, A. Purser, D. De Beer 2013. Resistance of Lophelia pertusa to coverage by sediment and petroleum drill cuttings. Marine Pollution Bulletin 75 (1): 132-140.

Brooke, S.D., M. W. Holmes, C. M. Young 2009. Sediment tolerance of two different morphotypes of the deep-sea coral Lophelia pertusa from the Gulf of Mexico. Marine Ecology Progress Series 390 (2009): 137-144.

DeepOcean, 2016. Environmental field report. NO.E10503.RE.16.089 (Gardline).

DeepOcean, 2017. Skarv – Visual Survey of Corals along Snadd Pipeline. NO.E10503.RE.17.152.

DeepOcean, 2018. Ærfugl survey report. NO.E11050-SUR-REP-006

DNV, 2013. Guideline - Monitoring of drilling in areas with presence of deep water corals, Report Nr.:2012-1691.

DNV GL, 2017. Memo - Visual mapping data Snadd, Skarv, Tilje. Memo No:112T9PLC-6/ FJUKM.

DNV GL, 2018. Visual mapping at Ærfugl - Environmental survey report. Report No.: 2018-0714 OSPAR. 2010. Background document for Deep Sea Sponge Aggregations.

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APPENDIX A

Corals close to the route

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Name Area (m2) X ED 50 UTM 32N Y ED50 UTM 32N

ENV7

124 437596 7291673

Lophelia Coral garden Fauna combined Distance from pipeline

Distance form umbilical

Dead/poor Single 3

^{12 m} ^{2 m}

ENV8

1479 437596 7291673

Distance form umbilical

Dead/poor Single 3

^{11 m} ^{1 m}

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ENV11

259 437541 7291626

Distance form umbilical

Dead/poor Common

⁵ Crossing 13 m Crossing 5 m

54

53 437013 7291526

Dead Poor 3

¹⁸ ⁸

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41

³⁷ ⁴³⁵⁸⁹⁹ ^7290682

Poor Poor 3 16 6

40

¹³⁴ ⁴³⁵⁸⁹⁷ ^7290671

Poor Poor 3

^{6 m} crossing 9 m

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39 28 435883 7290663

Poor Poor 3 17 m 7 m

22 32 435243 7290047

Poor Poor 3 17 m 7 m

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15 34 434443 7289283

Dead Poor 2 0,1 m 4m

Skarv BC 2_2 28 434425 7289262

Poor Fair 4 crossing 5 m 6 m

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5 18 434320 7289153

Poor Poor 3 5 15

ENV84 48 432613 7285268

Poor Single 3 2 0,3

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2032 86 434028 7284691

Dead Poor 2 - 10 m

2034 234 434205 7284731

Poor Fair 4 - 5 m

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2056 179 434132 7284750

Good Fair 6 - 13 m

2046 84 438409 7286072

Poor Good 5 - 2,5 m

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2049 454 435604 7286858

Poor Excellent 6 - 9 m

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Environmental impact assessment – Pipeline and wells

ÆRFUGL PHASE 1