Marine Laboratory, PO Box 101, 375 Victoria Road,

Aberdeen AB11 9DB

www. scotland. gov.uk/ marinescotland

Laura Anderson0131 244 3489MS.Chemicals@gov. scot

Keith Beaton

SEPA

15 June 2018

MARINE SCOTLAND SCIENCE RESPONSE

CORALLIAN - Wick Offshore Exploration Well CAR Application CAR/L/166721

Marine Scotland, Marine Laboratory has reviewed the Chemical Risk Assessment included in the aboveSupporting documentation. If this was a standard chemical permit submitted under the Offshore ChemicalRegulations 2002 (as amended 2011) the following comments would need to be addressed:

1. The Offshore Chemical Regulations 2002 (as amended 2011) require all products used and dischargedoffshore to be registered with Cefas. The Cefas certification for the following products will expire prior tocommencement of operations in September. Therefore you should contact your supplier to check if they havesubmitted information to Cefas for re-certification.

C-Dye expires 24/07/2018BridgeMaker II LCM expires 28/07/2018Dulon Eco Safe Rig wash expires 08/08/2018

2. The Offshore Chemical Regulations 2002 (as amended 2011) require that the latest Cefas template be used. The following products have more recent Cefas templates than those provided in the CAR Supportingdocumentation and should be used:

HALAD-300L NS Version 12 availableStack Magic ECO CLDS Version 2 availableBaraCor W -476 Version 2 availableJET-LUBE NCS-30 ECF Version 9 available

3. Using the most recent Cefas template Version 11 for TUNED LIGHT XL indicates that this product is notPLO. Table 5.3.2 of the CAR Supporting documentation should be amended accordingly.

4. In order to allow Marine Scotland to model the site specific RQs for the discharge of products during drillingoperations the following parameters should be provided rather than the default parameters for a referenceinstallation in 150 m of water:

Mean Residual Current (ms-1) Platform Density (Platform km-2) Organic Fraction In Sediment

5. The EIA Justification document has the drilling period as between September 2018 and February 2019 witha total of 30 drilling days. The CAR Supporting documentation has the spud date as 01/09/2018. For achemical permit under Offshore Chemical Regulations 2002 (as amended 2011) an end date is required. Canyou confirm that the earliest commencement date will be 1st September 2018 and the latest completion date willbe 28th February 2019?

Marine Laboratory, PO Box 101, 375 Victoria Road,

Aberdeen AB11 9DB

www. scotland. gov.uk/ marinescotland

6. The EIA Justification document states ‘During the proposed drilling operations, seawater, sweeps and water-based mud (WBM) will be used to facilitate the drilling processes and ensure the safe comple tion of the well’. Can you clarify what is meant by the safe completion of the well? Will any products be required for completionoperations? If so, these products have not been included in Table 5.3.3 of the CAR Supporting documentation.

7. The EIA Justification document states ‘The well will not be flow tested (i.e. no reservoir hydrocarbons will beflowed to the surface)’. However, the CAR Supporting documentation repeatedly mentions oil contaminationand includes an oily water separator. There are no oil based mud products included, can you clarify what oilcontamination there would be?

8. Section 8.3.1 of the EIA Justification document states ‘discharged at sea at approximately 2 m below the seasurface’. This does not correlate with Section 3.2 of the Supporting documentation which states ‘a 12 inchrubber hose approximately 5 metre below sea surface’. Can you clarify if there are two different dischargepoints for topside discharges?

9. Section 3.3 of the CAR Supporting documentation states ‘The effluent is typically discharged in batches of 2to 5 m3’. This does not correlate with the BDF discharge volume entered in Table 5.3.3 for Dulon Eco Safe Rigwash which is based on 3 m3. Can you confirm the discharge volume for Dulon Eco Safe Rig wash? Can youclarify if there are any products required to treat the effluent prior to discharge as none have been listed in theutility chemicals table?

10. Section 4.3.2 of the Supporting documentation includes Guar Gum. However, this product has not beenincluded in the drilling chemical tables. Can you clarify if Guar Gum will be required during drilling operations?

11. Section 3.7 of the EIA Justification document and Section 4.3.2 of the CAR Supporting documentationstates ‘based on historical data of similar cement jobs and is equivalent to 200% excess’.

a) Can you clarify what historical data this is based on? Has there been other similar wells drilled in this arearecently? How realistic is it to assume this well will also require 200% excess cement? What properties ofKimmeridge clay mean that you need excess cement to be pump? Are you expecting losses to the clay?

b) 200% excess cement being pumped onto the seabed is not typical and seems excessive. What dispersionmodelling has been undertaken for this large amount in relatively shallow water. The effect this discharge wouldhave on the marine environment, including dispersion and smothering effects and the potential for interferencewith decommissioning works at a later date should be discussed.

c) Can you clarify what is meant by good returns and how would it be measured?

d) C-Dye has been included in Table 5.3.2. Will this be pumped ahead of the cement slurry for the ROV todetect? Can you clarify if C-Dye would have 100% discharge at the seabed during drilling of the top hole 36inch section?

e) ‘Full excess being pumped if the ROV is not available’. Is it possible not to pump cement unless the ROV isavailable to avoid excess cement being deposited on the seabed?

f) There is an estimated discharge of 10% of cement slurry products and 20% of cement spacer products withinthe cement chemicals table. Can you confirm that this includes the 200% excess pumped during cementing ofthe top hole conductor?

g) Conventionally, in a chemical permit submitted under Offshore Chemical Regulations 2002 (as amended2011) there would be a section devoted to cementing operations. This would include: discussions on how thecement would be mixed; batch in pits/tanks or fly mixed in dedicated units, the capacity of the mixing pits/units; what the discharges in Table 5.3.2 represent (10% discharge for CM products and 20% discharge for CSproducts entered in Table 5.3.2) and their relation to the batch dilution factor parameters and discussion of theplugs (will any mechanical plugs be required).

h) Section 8.3.2 of the EIA Justification document states ‘A small proportion of the cement used to secure theconductor and casings in place within the wellbore will be discharged to the seabed during the proposed11/24b-D drilling operations’. Is this comment still applicable when the top hole 36 inch drilling section has adischarge of 200% excess cement?

12. POTASSIUM CHLORIDE SALT has been included in the chemical table for the 36, 17.5 and 12.25 inchdrilling sections. However, the Cefas template provided is for POTASSIUM CHLORIDE. Can you confirm whichproduct is required?

Marine Laboratory, PO Box 101, 375 Victoria Road,

Aberdeen AB11 9DB

www. scotland. gov.uk/ marinescotland

13. STEELSEAL ( all grades) has been included in the chemical table for the 36, 17.5 and 12.25 inch drillingsections. However, the Cefas template provided is for STEELSEAL. Can you confirm which product isrequired?

14. NF-6, Halliburton has been included in the chemical table for the cementing. However, the Cefas templateprovided is for NF-6, Baroid. Can you confirm provide the Halliburton template in addition to the Baroidtemplate which is for the NF-6 used in drilling?

15. Inconsistencies between Section 5.3.2 and the chemical tables:

a) C-Dye has a CHARM Algorithm code of CS, however the batch dilution factor is the same as the other CMproducts. Can you clarify if the C-Dye will be added to either the cement mixwater or spacer fluid? Or if thisproduct is mixed separately?

b) The BDF parameters provided for CM products are 1.03, 60 and 3 with the BDF as 3.46 E-04. Using theseparameters Marine Scotland generates a BDF of 4.26 E-04.

16. The risk based justification for CFS-926 provided in the CAR Supporting documentation:

a) States ‘slight to no toxicity’. This does not correlate with the latest Cefas template and is misleading, pleaseamend.

b) The justification also describes the use of this product as a pill. This does not correlate with the drillingchemicals tables were the discharge has been modelled as part of the drill fluid, that is DR. Can you confirm ifthis will be used as a pill? If so, the discharge should be modelled using CWO. Please note that there is nomention of a pill in Section 4

c) RQs which are greater than 1 indicate a significant risk to the marine environment. What is the actualdischarge rate of the chemical and how long will the discharge take to complete? Can you put this in contextwith the tidal currents and wind speed in the area? Could the length of time between use and discharge of thechemical be sufficient to reduce the toxicity or result in significant biodegradation of the chemical?

17. The risk based justification for GASSTOP LIQUID provided in the CAR Supporting documentation:

a) As it contributes to mitigation the justification should include that this is a contingency product.

b) The justification mentions HPHT work. Can you clarify if this well is expected to be at high pressure or hightemperature?

18. Section 5.4 of the CAR Supporting documentation states ‘Toxicity effects on the coastal water bodyresulting from the discharge of chemicals are considered to be negligible’.

a) Can you clarify if this includes the 200% excess of cement pumped when the ROV is unavailable or in badweather?

b) The discharge of CFS-926 generates an RQ>1 which does not indicate a negligible adverse impact.

19. What is the fate of the 5% of drilling products not discharged during drilling operations? Please note thatSection 8.4 of the EIA Justification document states ‘Recovered WBM will be reused / re-circulated wherepractical’. Will the 5% loss be during recovery? If so, there is still a 95% discharge during drilling of all threesections.

Please do not hesitate to contact us if you have any comments or queries. Marine Scotland are aware that thismay not be information normally assessed as part of the CAR licence process and would be happy to discussthe comments at a face to face meeting if this would be helpful.

Please note that only the chemicals included in Section 5 of the Supporting documentation have beenassessed.

The assessment of this application was conducted by Peter Hayes, Margaret McCann and Jane Heron. Anycorrespondence should be sent to MS.Chemicals@gov. scot

Marine Laboratory, PO Box 101, 375 Victoria Road,

Aberdeen AB11 9DB

www. scotland. gov.uk/ marinescotland

Regards

Laura AndersonOffshore Environmental and Chemical Coordinator