drilling in sensitive areas

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DNV SERVING THE OIL AND GAS INDuSTRy DRILLING IN SENSITIVE AREAS

Drilling in sensitive areasA GuIDELINE fOR “BEST PRAcTIcES” KEEPING fOcuS ON THE SEABED ENVIRONmENT

2 I DNV SERVING THE OIL AND GAS INDuSTRy I Drilling in sensitive areas I

IntroductIon

Situation: The offshore industry is moving closer and into sensitive seabed areas on the Norwegian shelf. Areas with cold water corals, with deep sea sponge aggregations or spawning grounds for sand eel and other benthic resources.

complication: many energy companies are new or unacquainted with drilling in sensitive seabed areas, are unaware of requirements, rules and best practices for operating (drilling, anchor handling etc.) and have limited environmental knowledge.

2 I DNV SERVING THE OIL AND GAS INDuSTRy I Drilling in sensitive areas I I Drilling in sensitive areas I DNV SERVING THE OIL AND GAS INDuSTRy I 3

Question: How can oil and gas companies uphold the value of conducting business in an environmental responsible manner following requirements and best practices for operating in sensitive areas, and at the same time generating profit?

This guideline will focus on drilling in sensitive areas, providing info and guidance to our clients.

This brochure is intended as a quick reference manual and guidance for companies venturing into areas in Norway that might be considered as sensitive. It will answer the following key questions:

n What are regarded as sensitive fauna and habitats, and where can one expect to find it?

n What should be taken in to consideration when planning for operations and applying for discharge permission in areas regarded as sensitive?

n How can we monitor the impact our activities have on the marine seabed environment?

The brochure will also give a best practice approach to drilling operations step by step, keeping focus on the seabed environment at reasonable costs.

In addition it will provide an overview of relevant DNV services that can be tailored to address these challenges.


If sensitive fauna is found in the area, there might be a call for environmental impact assessments and monitoring of activities affecting the seabed habitats. Adverse effects from drilling, anchor operations, seabed construction, and pipe laying should be held as low as possible.

Increased need for mappIng and monItorIng of sensItIve faunaInventories of red-listed species and vulnerable habitat types in Norway are growing, as is public awareness, and the companies’ corporate responsibility. When companies plan activities in areas with possible sensitive or red-listed marine fauna, the government generally demands visual mapping of the seabed habitats within the expected area of the activities.

This focus on corals and other potentially vulnerable natu-ral resources has led to a profound increase in the need for sensitive species mapping and environmental monitoring during petroleum operations. Necessary extra surveying, baseline surveys and monitoring depends on the geographi-cal areas in which activities are taking place.

Benthic communities with sponges and corals are difficult to identify or monitor with the methods used in traditional sediment monitoring (e.g. grab sampling). Destructive sampling and monitoring methods like trawling and ben-thic sledges are also not suitable, because of the sensitive nature of vulnerable habitats. Visual surveys using an ROV (Remotely Operated Vehicle), drop camera, or towed video platform is favourable methodological options for investi-gating potentially vulnerable areas of the seabed without damaging it. A standard for visual surveys has been devel-oped (NS-9435, Norsk Standard, 2009), to ensure quality of work and to allow for repeatability assuring that comparable studies can be implemented.

One of the challenges of visual research and analysis of benthic communities is to identify the individual species’ tolerance to impacts in relation to seasonal variation, distri-bution patterns, age/life stage, behavioural and biological properties, and then draw conclusions in a larger context. Comparisons of data from side scan sonar, multibeam echo-sounder, catch statistics from trawling activity, and compari-son of research results and surveys conducted in the region, are important elements in understanding the big picture.

BACKGROUNDDuring offshore activities and other physical/mechanical interventions on the seabed, there are many potential environmentally harmful processes, from oil leakage to smothering by sedimentation. By imple-menting a risk-based environmental strategy, work can be carried out efficiently at low risk the environment.


Pipelaying

Subseaconstruction

Drilling

ExplorationAnchor

operations

Piledriving

Smothering Chemicals Habitat deterioration

Physicaldamage

Noise and vibration

SENSITIVE FAUNA BIODIVERSITY HOT SPOTSSPAWNING GROUNDS

Impacts and effects to sensitive fauna from offshore activities


maIn areasMid Norway/ Haltenbanken

descrIptIonCorals are most abundant on the continental shelf in mid-Nor-way at 200-400 m depth. The highest densities occur along the continental break and on edges of shelf-crossing trenches (Fosså et al 2002).

The stony coral Lophelia pertusa is regarded as a threatened species according to the Norwegian Red List for species (Kålås et al., 2010, based on UICN defininitions) and OSPAR 2008a. Also, according to OSPAR 2008b, and according to Norwegian Red List for habitats (Lindegaard and Henriksen 2011), “Coral gardens” are defined as a relatively dense aggregation extend-ing over at least 25 m2 of colonies or individuals of one or more coral species, such as leather corals (Alcyonacea), gorgonians (Gorgonacea), sea pens (Pennatulacea), black corals (Antipatharia), hard corals (Scleractinia) and, in some places, stony hydroids (lace or hydrocorals: Stylasteridae).

Other red-listed species such as redfish (Sebastes) are often found inhabiting the coral reef systems in Norway.Considerable knowledge on the corals at the Norwegian Continental Shelf has been assembled in recent years, due to impacts the offshore and fishery industry may have on corals. Governmental measures like establishment of mapping pro-grams (MAREANO), protection of specified areas and regula-tions have been developed.

sensItIvItyCorals, in particular Lophelia, are sensitive to smothering/sedimentation and physical damage from e.g. anchor opera-tions. Chemical effluents and accidental spills will also have the possibility of adversely influencing coral health and reproduc-tive capability.

Coral Gardens

The following section will provide information of important characteristics and where special care generally needs to be taken in the planning of drilling activities.

LophELIA pERTuSAThe cold water coral Lophelia pertusa is the most common reef building stony coral in the North Atlantic Ocean, creating a diverse habitat for more than a thousand different species. L. pertusa is found on both sides of the Atlantic Ocean from 30 m. down to 3,000 m. but generally found at depths deeper than 300 m. L. pertusa is known for being relatively slow-growing, and the largest reef structures are more than 9,000 years old. L. pertusa requires temperatures between 4 and13°c and salinities of around 35—38 psu, with oxygen concentrations >3 ml l-1 (freiwald et al. 2004; Taviani et al. 2005; Dodds et al. 2007; Davies et al. 2008).

CoRAL REEFS

CoRAL AREAS

The cold water coral Lophelia pertusa

WHAT IS SENSITIVE FAUNA?


maIn areaBarents Sea

descrIptIonHigh densities of sponges are mainly found in the north of Norway, like Tromsøflaket and the Barents Sea, but spread communities of sponges are also found at Haltenbanken and in the North Sea. Sponges are benthic and filter-feeding animals that mainly live in the marine environment.

Within Norwegian waters there are 260 species of sponges, with the class Demospongia accounting for most of the species present. Water depths where sponges are usually found are between 250 and 1,300 m (Bett and Rice, 1992). Sponges occur on both hard substrata, such as boulders and cobbles, or on soft substrate. Higher densities are usually found in higher aggregates on hard bottom substrat. Sponges are often found on iceberg plough-mark zones because stable boulders and cobbles provide attachment for sponges.

Deep-sea sponge aggregations are on the OSPAR list of threatened and/or declining species and habitats (OSPAR Agreement 2008 – 7). Deep-sea sponge aggregates are pri-marily composed of the classes Hexactinellida and Demospongia (OSPAR 2010). There are 33 sponge species that are classified on the Norwegian Red List (Kålås et al., 2010), and all but one species are classified as Data Deficient (DD). Twenty of the species on the Red List belong to Demospongia, with 19 classified as (DD) and one as Near Threatened (NT) (Norwegian Red List 2010).

sensItIvItySponge bed habitats are sensitive to sedimentation and smothering, and disturbance and removal by trawling.

Deep-sea Sponge Aggregations

DEEp SEA SpoNGES

Soft bottom sponge habitat

hIGh DENSITy SpoNGE AGGREGATIoNS


maIn areaNorth Sea

descrIptIonThe Lesser sand eel has been an important commercial fish with landings of over 300,000 tons/year in Norway. Due to overfishing the stocks have fallen; in the Norwegian eco-nomic zone the stocks were reduced 88–94% between 2003 and 2005, and today the sand eel fishery is closed except for a smaller experimental quota of 40,000 tons (2012). The active measures made by the Norwegian government have though, resulted in a positive increase in sand eel stocks and in 2010 it was no longer critically threatened, and so removed from the Norwegian Red List.

sensItIvItyCaution must be taken when operating in areas with poten-tial sand eel populations. Sand eels are shown to be sensitive to seismic shootings (Hassel et al., 2004), and fishermen have repeatedly reported that trawl catches decrease when a seismic ship is operating in the area. The potential impact by pollution and sedimentation due to drilling operations is high because of their stationary habits. Sand eels are also potentially sensitive to noise pollution from drilling activities.

Sand eel spawning grounds

SAND EEL AREAS

AmmoDyTES mARINuSThe lesser sand eel (Ammodytes marinus) is a north Atlantic fish species found from the Barents Sea down to the Baltic Sea and Great Britain. The sand eel spends most of its time buried in sandy sediment of preferable depth of 30–70 m. (Wright et al., 2000), but can be found at 15–120 meters. It is only active during the light hours of the year hunting pelagic and feeding on zooplankton, fish eggs and fry. During the wintertime the sand eel goes in to dormancy, buried in the sand, and except for spawning which occurs in December to January, it remains inactive until spring time, usually April.

The lesser sand eel is selective in which type of sediments it burrows, not too fine so that the pore water can be oxygenated and not a too high content of fine gravel or larger, making digging difficult. A mixture of coarse and medium fine sand with a low silt and pelite content (< 10%) and small amounts of gravel (<10%) is a preferable substrate (Wright et al., 2000; Holland et al., 2005).The sand eel reaches a maximum length of 24 cm, lives a maximum of ten years, and is important food source for many fish, mammals and sea birds.


Photo: Rudolf Svensen


petroleum safety authorIty, 2011Duty to monitor and record data from the external envi-ronment according to Section 48 of the Framework Regulations, as specified in Chapter X (Sections 52 to 59) of the Norwegian Activities Regulations (Petroleum Safety Authority, 2011), particularly the surveying of vulnerable environmental resources (defined by Section 53 of the Activities Regulations), which includes coral reefs, sponge havens, spawning grounds and other.

stortIngsmeldIng no. 8, 2006In the management plan for the Barents Sea, vulnerability is defined as the ability of a species or the area where it is living to maintain its natural state related to external, often anthropogenic influences. Habitat-shaping or forming species like corals and sponges are clearly addressed as potentially vulnerable.

the norwegIan red lIst for specIes (Kålås et al., 2010), the Norwegian Red List for Habitat types (Lindegård and Henriksen, 2011). The Norwegian Red List includes 4,599 species (Lindstrøm et al., 2010).

the norwegIan nature dIversIty act (Law 2009-06-19 no. 100) applies to the continental shelf

and impel that a precautionary principle is used when carry-ing out activities that might damage or disturb the seabed habitats (§9).

the pollutIon control act to protect agaInst pollutIon and waste Under Section 49 of the Act of 13 March 1981 No. 6 there is a duty “to provide the pollution control authority or other public bodies with any information necessary to enable them to carry out their tasks pursuant of this Act”.

the marIne resources act (2008) The Marine Resources Act aims to ensure sustainable and economically profitable management of wild living marine resources and genetic material derived from them, while minimising impact upon non-target species.

the nature conservatIon act (1970) The act aims to protect natural habitats and wild flora and fauna of Norway. 2,700 km2 of Norway’s marine waters and 68 species (terrestrial and aquatic) are protected under this act.

the wIldlIfe act (1981) The act was formed to protect the external environment from pollution and to reduce existing pollution, this applies

INTERNATIONAl AND NATIONAl lEGISlATIONRelevant to marine conservation in Norwegian waters.


to exploration, for recovery and exploitation of submarine natural resources on the continental shelf, including the cessation of such activities.

ospar (2008, 2008a) Habitats and species listed as threatened or declining by OSPAR. Norway has an international responsibility to safe-guard a representative selection of fjord and coastal areas types not found anywhere else in the world.

the Bern conventIon (1979)The aims of this Convention are to conserve wild flora and fauna and their natural habitats, especially those species and habitats whose conservation requires the cooperation of several states, and to promote such cooperation.

the norwegIan water management regulatIons This incorporates the EU Water Framework Directive into Norwegian law. The objective is to achieve good ecological and chemical status for all water bodies by 2021. The regula-tions apply to inland and coastal waters out to the baseline. Norway is also making management plans for its jurisdic-tional areas of the North Sea, the Norwegian Sea and the Barents Sea (State of the Environment Norway, 2007). However, The Water Management Regulations are not intended as a tool for regulating harvesting of fish stocks or other marine resources, nor for regulating the aquaculture industry along the coast.

havmIljø.noCooperation between central administrative bodies and research institutions to establish a common database on natural resources and their vulnerability.

■■ Havforskningsinstituttet (HI)■■ Norsk institutt for naturforskning (NINA)■■ Klima- og forurensningsdirektoratet (Klif)■■ Norsk polarinstitutt (NP)■■ Norges geologiske undersøkelser (NGU)■■ Statens kartverk sjø■■ Det Norske Veritas (DNV as consultant for the analysis system)


early plannIng More than often, environmental regulations are over-looked by the oil and gas companies and therefore are addressed too late in the process, resulting in costly addi-tional work. An environmental pre-study is a simple meas-ure that can reduce cost, structure and simplify the work-flow. If you are a new actor on the Norwegian Shelf or otherwise need advice on how to proceed when awarded a field in a sensitive area, DNV can conduct a desktop pre-study based on our extensive data and knowledge gained

from years of experience. A pre-study can include an intro-duction to Norwegian environmental legislation, interpre-tation of data, identification of sensitive areas and recom-mendations on how to proceed.

sIte survey & BaselIne dataA natural first step of a monitoring program is to start with a site survey, mapping the location with side scan sonar and multibeam echosounder.

PlANNING A DRIllING OPERATIONfor drilling in sensitive areas, a precautionary approach is important. DNV can assist in planning and monitoring the environmental impact, and we deliver a series of services that can contribute to a successful drilling operation, with the smallest possible impact on the environment.

36–6 months in advance

Resourcemapping

Impact assessment

Finalisation of plans

Discharge permission from Klif

PLANNING DRILLING




Gather existing data/ information

Perform anchor analyses

Plan spud location

Perform discharge planning

Other

Best Fit Analysis

Coral/ Sponge Risk Assessment

Dispersion Modelling

Mitigating Advisory

Monitoring program

Discharge application to Klif

Mapping of environmental resources

Verify data with visual mapping

Pre-study

During drilling

After drilling

Deployment of monitoring equipment

Sediment sampling

Selected coral structures at risk visually examined and documented

Visual mapping

Sediment sampling

Retrieval of monitoring equipment

Current

Turbidity

Sedimentation rate

Baseline/ before drilling/anchor operations

Monitoring

Measuring:

Recommended Workflow with timeline


Treat all potential structures as worthy of protection?

Technical mitigation measures /Risk

reducing measures

Drilling campaign

Perform visual mapping

Discharge application + permit

Perform Impact assessment

Develop Monitoring

Program

Monitor activities

YES

YES

YES

NO

NO

NO

Corals within 500 m of drill location?

Based on:

Move spud siteUse of CTS Move anchor corridorsUse DP rigTransport cuttings to shoreReroute pipe corridorsReduce drill bit size

E.g.

Drilling dischargesPlume impact Accidental dischargesAnchors and chain impactPipe laying impact

E.g.

Documentation

Are potential coral structures identified

within the site?

Site survey resultsDNV service

Action required

Climate and Pollution Agency (KLIF)

Colour codes

Pre-cautionary distances/ dispersion modelsPlanned technical solutions

Corals within 30 m of anchor corridors?

Corals within 10 m of pipe laying corridor?


To measure the benthic footprint of a drilling campaign, it is crucial to know the environmental conditions before drilling – The Baseline. There are no general requirements to perform a baseline survey prior to exploration drilling. However, according to the Activity Regulations (Requirements for Environmental Monitoring of the Petroleum Activities on the Norwegian Continental Shelf-regulation 2010-04-29 no. 613) baseline surveys need to be performed prior to:

■■ Exploration drilling in new areas with unknown nature types, or where presence of vulnerable environmental resources has been proven to be found in association with sediments.

■■ In other areas, prior to production drilling and develop-ment start at each of the fields.

Depending on where and what sensitive environmental resources are expected, different parameters can be included in the baseline survey:

■■ Visual mapping, with ROV or drop camera, of poten-tially vulnerable resources.

■■ Sediment chemical and grain size characterising from sediment core samples.

■■ Turbidity.■■ Benthic fauna diversity.■■ Currents.■■ Background noise.

DNV has extensive experience in conducting baseline sur-veys and can help with both planning and execution.

mappIng of seaBed featuresSide scan sonar and multi-beam echo sounder are com-monly used during site surveys in order to collect data of the seabed features in an efficient way. The area covered using these methods may vary, but a typical size is at least 4x4km. The data provided from the side scan sonar in a

mosaic image, create the basis for interpretation of poten-tial coral structures within the surveyed area. The multi-beam echosounder primarily collects depth data, and will reveal seabed features such as ice scouring plough marks.

InterpretatIons of sIde scan mosaIcAll potential coral structures down to the limitation of the resolution of the mosaic should be:

■■ Circled as accurately as possible around the outermost edges of the structure.

■■ Geo referenced in the middle of the structure (for tabu-lated purposes).

■■ Area for each structure calculated (for tabulated purposes).

■■ Labelled with a unique number (for tabulated purposes).

■■ A buffer around each structure should be made to reflect the limits of accuracy of the positioning of the mosaic.

vIsual mappIngPotential coral structures or general sponge distributions identified by multibeam echosounder and/or sidescan sonar survey should be surveyed by visual methods. Techniques and methods to be followed are given in Norwegian Standard NS9435 (NS, 2009). When conducting a visual mapping, the use of a ROV is highly recommended, documenting possible coral structures and sponges detected in the planned drilling area. The size and condition of these are registered and categorised in groups in accordance to condition and coverage.

DNV has high competence and experience with visual map-ping from numerous operations. We offer mapping with our own ROV, or guidance and advisory on a survey ship. We are highly skilled in interpreting underwater film and footage.

VISUAl MAPPINGSonar and echosounder data collected during a site survey are analysed, and the results act as the basis for further decisions to conduct an eventual visual mapping operation.


cORALSParagorgiaLophelia

SPONGES

“CommoN DENSITy”

“hIGh DENSITy”“hIGh DENSITy”

“CommoN DENSITy”“CommoN DENSITy”

“SCATTERED DENSITy”“SCATTERED DENSITy”

“SpARSE / SINGLE INDIVIDuALS”“SpARSE / SINGLE INDIVIDuALS”

“GooD“ refers to apparently intact L. pertusa.

“moDERATE“ refers to reefs containing both dead and living colonies of L. pertusa.

“pooR“ indicates an area dominated mostly by dead corals with relative small patches of living L. pertusa.

“DEAD“ No living colonies of Lophelia pertusa are observed in these areas.


The risk assessment should be used as decision support with regards to drilling location, discharges of drill cuttings and sediment, location of anchors, anchor chains, pennant wires etc.

By systematically evaluating the risk inflicted upon corals or other fauna in an exploration area, operators can plan for exploration drilling with the lowest possi-ble environmental impact. Also, by working out an overall risk picture it’s easier to tailor the monitoring program, focusing on those coral structures/habitats that may be at risk. To perform an impact assessment, it is important to have proper background data.

dIspersIon modellIng of drIll cuttIngsDrill cuttings and drilling fluids may affect sensitive habitats by an increased sedimentation and particle exposure. The positioning of the well and the deposit site is therefore important. Calculating the particle dispersion depending on the currents and finding the least harmful area to deposit drill cuttings is recom-mended. Deposition can be made far away from the well using e.g. a CTS (Cuttings Transport System). If it is impossible to secure the safety of the sensitive habi-tats, it could be necessary to bring the cutting residues back to the rig for alternative disposal.

anchor and moorIng handlIngCorals and sponges are especially sensitive to the mechanical disturbances that anchor and mooring handling inflict. The mandatory anchor and mooring analysis should consider corals and other protected habitats when planning for positioning and handling, e.g. a “best fit analysis” calculating the best anchor line positions avoiding coral damage.

pIpe layIng Laying and maintaining pipes have a relatively large local environmental impact. The biggest risks to sensi-tive fauna by pipes are physical disturbances and leak-

IMPACT ASSESSMENTIt is recommended to perform an impact assessment in relation to anchor operations and discharges and spreading of drill cuttings and mud.

DATA OPTIONAL OR

mANDATORy

DEScRIPTION

Drilling plan mandatory A plan describing the drilling operation,

volumes of mud and cuttings expected,

duration for each section, location and more.

map showing

potential coral

structures

mandatory This kind of map is normally based on sonar

data and interpreted by qualified personnel in

order to point out potential coral structures.

coral survey

data

Recommended Data confirming the presence of corals, coral

condition, coral species and distribution. Such

data are not available from sonar data (map)

only. These data make it possible to distinguish

coral structures which will strengthen the risk

assessment.

current data Recommended Important data in order to as good as possible

assess the current regime at a given location

which is important with regards to spreading

of discharges.

modelled

dispersion

plume

Recommended A modelled plume gives an overview of

dispersion and sedimentation rates which are

essential when assessing possible impacts

inflicted upon cWc. Should be based on input

from current measurements from the location

if possible. If not available, one has to refer to

experiences from similar operations.

Anchor

analysis

mandatory Location of anchor, anchor chains, pennant

wires etc. A description of pre lying, pick up

and more. These are important data in order

to assess the risk inflicted upon cWc with

regards to anchoring.

Noise

pollution

analysis

Recommended Acoustic modelling and measurements analys-

ing possible impact on sensitive species like

fish and marine mammals from drilling and

seismic activities.


age. A risk assessment based on the site survey should pre-sent the best route, avoiding sensitive areas. Reducing the risk of leakage due to anchor and other physical damages to the pipe is also important mitigating measures.

mItIgatIng measuresAfter the site survey and risk assessment are conducted, potential measures to mitigate the drilling operations impact on sensitive fauna should be planned. Examples of risk-reducing measures are:

■■ CTS (Cuttings Transport System)■■ DP drilling rig (Dynamic Positioning)■■ Reduced drill bit size ■■ Onshore disposal of discharges

An environmental resources map (coral

condition from interpretation of SSS

mosaic and visual mapping).

Deposition distances for discharges given in

mm (based on imperical data or

worst case dispersion modelling).

Probability plot based on historical current

measurements.

50 mm10–50 mm

1–10 mm

0.1–1 mm

<25%

75–100%

50–75%%

25–50%

NO > SLIGHTLY (0.1–1 MM)

SLIGHTLY > MODERATE (1–19 MM)

MODERATE–SEVERE (10–50 MM)

SMALL (>50 MM)

Considerable

Moderate

CONSEQUENCE

MinorNo

LIKELY

LARGE

MODERATE

SMALL

NO/MINOR

NO/MINOR

NO/MINOR

NO/MINOR

NO/MINOR NO/MINOR NO/MINOR

LOW LOW

LOW

CONSIDERABLE SEVERE SEVERE

SEVERECONSIDERABLE

CONSIDERABLE

Deposition of discharges from drilling. Digital illustration: 3DGroundline


Pipelaying

Subseaconstruction

Drilling

ExplorationAnchor

operations

Piledriving

Threats

Effect on Sensitive fauna

Monitoring methods

Turbidity measurements

Sediment sampling

ROV inspection

Current measurements

Sediment traps

Hydrocarbon Sniffers

Passive Samplers

Current measurements

Sediment traps

Sediment sampling

Hydrophones

Geophones

ROV visual inspection

Smothering by sedimentation

Contamination from chemicals (accidental spills etc)

Physical/ Mechanical Damage

Noise/vibration impact

Environmental monitoring

ENVIRONMENTAl MONITORING

monItorIng programWhen drilling in sensitive areas, it is important to moni-tor the different effects on the surroundings, before, during and after drilling. Which method and equipment to use depends on the sensitive resources present and

what operations are being conducted. The figure bellow shows the threats, effects and an overview monitoring methods and when they are best applied. Details on applicable monitoring methods are given in the table to the right.

Possible impact on sensitive fauna is documented by monitoring anchor handling and drilling operations. Evaluating status before, during and after operations.


SAmPLE/ANALySES DEScRIPTION PuRPOSE

Sediment traps Vertical cylinders “trapping” sinking particles in the

water column.

collect particles to be analysed for grain size distribution, barium and other

metals. Increased levels will indicate spreading of drill cuttings.

Sediment samples core samples which can be cut in various depth

intervals, e.g. surface sediments and deeper

sediments.

Samples to be analysed for drill cutting constituents, thus mapping the spread

of drill cuttings.

ROV inspection use camera on ROV. Visual evaluation of the particle dispersion in water and at the seabed.

Observe excessive sedimentation.

used in sediment sampling and deployment of equipment.

Turbidity Sensors measuring the transparency of the water,

thus indicating particle concentrations. The data are

stored in the sensor.

Indicate particle concentrations in the water to reveal spreading of drill

cuttings.

Water currents Sensors measuring water currents (velocity and

direction). can be of profiling type (measuring in

the whole water column) or single depth

measurements.

Gives the main current direction and velocity at certain depths for a period of

time. main parameter regarding expected direction of dispersion, and when

deciding where to place the measuring equipment/sampling stations.

Passive samplers

(DGT etc)

Diffuse Gradients in Thin-film (DGT) Passively

measures dissolved and particularly bound metals in

the water over time.

Detects increased consecrations of metals and can be used to monitor the

discharge of metals from drilling operations.

Hydrophones/

geophones

Sensors measuring sound waves and vibrations. Obtains data on possible noise pollution and impact from tremors and

vibrations through the seabed.

Suggested applicable monitoring methods for each of the identified sources with potential of influencing coral communities.


Bett, B.J., & Rice, A.L. 1992. The influence of hexactinellid sponge (Pheronema car-penteri) spicules on the patchy distribution of macrobenthos in the Porcupine Seabight (bathyal NE Atlantic). Ophelia 36 (3): 217-226.

Davies AJ, Wisshak m, Orr Jc, Roberts Jm. 2008. Predicting suitable habitat for the cold-water coral Lophelia pertusa (Scleractinia). Deep-Sea Res I 55:1048–1062

Dodds LA, Roberts Jm, Taylor Ac, marubini. 2007. metabolic tolerance of the cold-water coral Lophelia pertusa (Scleractinia) to temperature and dissolved oxygen change. J Exp mar Biol Ecol 349:205–214

fosså, J.H., P.B. mortensen and D.m. furevik. 2002. The deep-water coral Lophelia pertusa in Norwegian waters; distribution and fishery impacts. Hydrobiologia 417:1-12.

freiwald A, fosså JH, Grehan A, Koslow T, Roberts Jm. 2004. coldwater coral reefs. uNEP-Wcmc, cambridge

Holland G. J., Greenstreet S., Gibb I., fraser H., Robertson m., 2005. Identifying sand-eel Ammodytes marinus sediment habitat preferences in the marine environment. mar Ecol Prog Ser 303: 269-282.

Kålås, J.A., Viken, Å., Henriksen, S. and Skjelseth, S. (eds.) 2010. The 2010 Norwegian Red List for Species. Norwegian Biodiversity Information centre, Norway.

OSPAR. 2008a. OSPAR convention for the Protection of the marine Environment of the North-East Atlantic. OSPAR List of Threatened and/or Declining Species and Habitats. (Reference Number: 2008-6)

OSPAR, 2008b. OSPAR convention for the Protection of the marine Environment of the North-East Atlantic. Descriptions of Habitats on the OSPAR List of Threatened and/or Declining Species and Habitats (Reference Number: 2008-7, Replaces agreement 2004-7).

OSPAR, 2010. Background Document for Deep-sea Sponge Aggregations. OSPAR commission Biodiversity Series.

Norsk Standard. 2009. Vannundersøkelse - Visuelle bunnundersøkelser med fjernstyrte

og tauede observasjonsfarkoster for innsamling av miljødata. Water quality–Visual seabed surveys using remotely operated and towed observation gear for collection of environmental data. NS9435:2009.

Lindgaard, A. og Henriksen, S. (red.) 2011. Norsk rødliste for naturtyper 2011. Artsda-tabanken, Trondheim.

Wright, P.J., Jensen H, Tuck I., 2000. The influence of sediment type on the distribution of the Lesser Sand Eel, Ammodytes marinus. J. Sea Res 44:243–256.

Havmiljø.no

References

With rising pressure on the ocean’s resources, demands on minimal environmental impact solutions are increasing. DNV assists the offshore industry in improving its drilling operations and environmental performance.


Biodiversity Mapping

Environmental Impact Assessment

Coral/ Sponge Risk Assesment

Drill Cuttings Dispersion Modelling

Environmental Monitoring

Environmental Modelling and GIS

Oil Spill Contingency Analysis

Oil Spill Preparedness and Response

Oil Drift Modelling (OSCAR)

Environmental Technology and Engineering

Well Risk Assessment

Offshore Leak Detection Systems Advisory

Third Party Reviews

DNV ENVIRONMENTAl RISK MANAGEMENT SERVICES


contact: [email protected]

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