Armada Kraken UK FPSO PETS Subsidiary Application Template PRA/219. Chemical Permit Risk Assessment

Transcription

1 Armada Kraken UK FPSO PETS Subsidiary Application Template PRA/219 Chemical Permit Risk Assessment September 2016

2 Contents ACRONYMS 1 INTRODUCTION 4 2 CHEMICAL MANAGEMENT Non Chemical Technologies Chemical Selection Chemical Application Trial Chemicals Chemical Risk Assessment Chemical s Chemical Reporting Chemical Summary FPSO Commissioning 10 3 PROCESS CHEMICALS CHARM Chemical Selection 12 4 SEAWATER UPLIFT AND WATER INJECTION 24 5 UTILITY CHEMICALS CHARM Chemical Selection 24 6 PIPELINE COMMISSIONING CHEMICALS CHARM Chemical Selection 29 7 CONCLUSION 32 PRA/219 CP 2

3 Acronyms BDF BEIS CHARM CP CRA EEMS EIA EOSCA FPSO FWKO g/cm 3 HQ LP m 3 m 3 /h MAT mg/l MGP OCNS PLO ppm PWRI SAT SRB SUB VSD Batch Dilution Factor (Department for) Business, Energy & Industrial Strategy (formerly Department of Energy and Climate Change (DECC)) Chemical Hazard Assessment and Risk Management Cathodic Protection Corrosion Resistant Alloy Environmental Emissions Monitoring System Environmental Impact Assessment European Oilfield Speciality Chemicals Association Floating Production Storage Offload Free Water Knock-Out grams per cubic centimetre Hazard Quotients Low pressure cubic metre cubic metre per hour Master Application Template milligram per litre Marine Growth Prevention Offshore Chemical Notification Scheme Poses Little or No Risk (PLONOR) Part Per Million Produced Water Re-Injection Risk Quotients Subsidiary Application Template Sulphate Reducing Bacteria Chemical carries a Substitution Warning Variable Speed Drives PRA/219 CP 3

4 1 Introduction As detailed in the Armada Kraken Floating Production Storage Offload (FPSO) vessel Environmental Impact Assessment (EIA) document for PRA/219, a potential environmental impact was identified arising from the use and discharge of chemicals. This document provides more information on chemical management strategies and the associated risk assessments. 2 Chemical Management 2.1 Non Chemical Technologies The FPSO process system has been designed to reduce the need for chemical injection as far as possible. Examples of this are: The Free Water Knock-Out (FWKO) vessel in each process train separates the produced fluids into water and oil; the produced water leaving this vessel will contain approximately 1% oil-inwater. Each train includes hydrocyclones, compact floatation units (CFUs), electrostatic coalescer and slops tank treatment package, all of which help to reduce the oil and gas content of discharged produced water. For example, the CFU system is designed to meet an oil-in-water specification of 30 mg/l without chemical injection and 15 mg/l with chemical injection. A deaerator tower is used in the seawater lift system to remove dissolved oxygen and thereby reducing corrosion. A sulphate reduction package is used to reduce the sulphate and hence growth of sulphate reducing bacteria in the water injection line. The produced water system includes an inline oil-in-water analyser which monitors the OIW levels of the produced water as it enters the produced water transfer pumps. When a high (30 mg/l) OIW level is detected this analyser closes the overboard discharge line and routes the produced water to the off-spec produced water tanks, which themselves are routed back into the process at the FWKO vessels. A cathodic protection system protects all pipework, valves and support / protection structural steelwork. The cathodic protection is designed to supplement the coating system and is designed in accordance with DNV RP B401 and NORSOK M-503. Surface coatings on the hull/ superstructure/ process system/ tank systems and anodic/ cathodic protection (CP) system provide protection against corrosion. A Corrosion Resistant Alloy (CRA) material has been used throughout the topsides process, reducing the need for chemical corrosion inhibitor. Marine Growth Prevention (MGP) system which mitigates marine growth accumulation throughout the sea caissons/pump suctions and includes the use of anodes to counter the effects of corrosion. 2.2 Chemical Selection Bumi Armada work with their chemical suppliers, to effectively and responsibly manage the use of chemical on the Armada Kraken FPSO. Where practical, Bumi Armada will aim to select chemicals with least environmental impact and all products will be registered under the Offshore Chemical Regulations 2002 (as amended 2011). For the products which contain components identified for further technical justification and the replacement schedule is contained within this chemical permit Subsidiary Application Template PRA/219 CP 4

5 (SAT). Risk based justifications will be applied in the future when the annual chemical report is in place. 2.3 Chemical Application Information on the application and justification for the chemicals to be used on the Armada Kraken FPSO are detailed in Sections 3 to 5. Variations to this permit will be highlighted using text colour and/or yellow highlight for ease of navigation. Original text, where appropriate, will be struck through but retained in this document for reference purposes. 2.4 Trial Chemicals It will be necessary to have a suite of trial chemicals available on the permit to cover the initial start -up and operational period until all wells are available and in steady state. The performance of phase separation chemicals are affected by a number of parameters that are likely to fluctuate when the fields are first produced. Once the appropriate chemical(s) has been identified, the unnecessary chemicals will be removed from this permit through a permit variation. 2.5 Chemical Risk Assessment The chemical risk assessment has been completed using the Chemical Hazard Assessment and Risk Management (CHARM) model to assess the potential environmental risks associated with the use and discharge of CHARMable chemicals General The general assumptions made in the preparation of this application and during the calculations of the Risk Quotients () are detailed below and within this section. Specific assumptions for each product are detailed in the relevant justification Batch Dilution Factors The CHARM model risk assessment has taken into account the total fluids volumes, including produced water discharge to calculate the. The most up to date CEFAS ranked list was used to source templates. Note: Bumi Armada will continue to liaise with the chemical suppliers to ensure that the chemicals will be re-registered or will be submitted for re-registration at the appropriate time (generally eight-weeks prior to the expiry date). When application dosages have been provided in ppm, the product density has been used to convert the dosage into mg/l. Batch Dilution Factors (BDF) are calculated from: The density of the discharged fluid, normally equivalent to seawater, not the density of the product. The discharge rate of the discharged fluid. The total volume of fluid discharged. If the discharge parameters exceed the permitted range in CHARM, the worst case BDF of allowable will be used. This is also the BDF the CHARM algorithms use for any product discharged through the produced water system. This will generate a slightly higher than using the European Oilfield Speciality Chemicals Association (EOSCA) maximum values which generate a BDF of 9.95e-04. PRA/219 CP 5

6 If the discharge parameters are below the permitted range in CHARM, the minimum values (density of discharged fluid = 1.03 g/cm 3, volume = 3 m 3 and discharge rate = 60 m 3 /hr) have been used to calculate a BDF of 4.26E Injection Rates/Dosages The method of calculation for injection rates/ dosages is, where applicable, stated within the chemical tables below. The injection rates/ dosages used in the field can be higher than the standard application dosage shown in CEFAS templates. This is attributed to a number of reasons: Some biocidal and other similar treatments, follow a shock tactic to stimulate production, and prevent future operational difficulties. The dosage for shock treatments would therefore not be expected to be the same as for continual use in a production circumstance. Issues of brine and material compatibility, as well as effects on other processes within the system where other chemical products are already utilised, further necessitate higher injection rates than those proposed on the corresponding CEFAS templates. The latter are based mostly on laboratory or otherwise ideal experimental conditions and cannot take into account the multiple interactions found in actual field situations Annual Usage Figures The maximum application dosage for continuously applied products has been used for the purpose of CHARM modelling of the worst environmental scenario. This maximum application dosage may not be maintained on a continuous basis, and may be adjusted to reflect the changing fluid composition of the producing wells. Consequently the annual usage recorded in the chemical tables may not correspond to a yearly equivalent of this maximum application dosage. Therefore, it may not be possible to directly convert usage allowances into dosage in the case of continuously used chemicals. For batch treatment operations environmental modelling has been performed on the maximum batch size used in an operation to represent a worst case scenario. However, a unique batch size is calculated for every treatment, dependant on a number of factors including flow characteristics and residual product levels. Therefore the total use recorded in the chemical tables for batch use products will not always correspond to the frequency of treatment multiplied by the maximum batch use. T he total use may be lower as not all applications will use the maximum batch size Annual Discharge Figures Partitioning data has not been used to estimate the percentage of the product that will be discharged with the produced water therefore partitioning has not been considered in requesting discharge allowances. During commissioning activities, Produced Water Re-Injection (PWRI) will not be immediately available, however, PWRI will be started as soon as possible after commissioning. Process Chemicals For all chemical applications to the process estimated discharge allowances are based on the industry standard for water injection of 1% plus 15% to account for the estimated downtime of the PWRI system. Although the PWRI system is expected to be available soon after production begins, it has been assumed that 100% of the chemical may be discharged to sea during the first year of production (2017). For subsequent years, the discharge tonnages have been amended to reflect the assumed 1% discharge of chemicals that will be re-injected plus 15%. Seawater Uplift and Water Injection HOLD: required chemicals are currently under review and as such this permit will be updated once the information is available. PRA/219 CP 6

7 2.6 Chemical s A detailed description of the chemicals used on the Kraken Armada FPSO is presented below. Further justification has been included in the following circumstances: Where s >1; If s are calculated to be <1, but specific the chemical has an HQ >1 (Silver, White, Orange, Blue and Purple); or Non-CHARMable chemicals with OCNS groups that indicate a significant toxic potential (i.e. OCNS category A, B or C). Where a chemical has multiple uses and therefore multiple discharge routes, each application has been included in a separate table. Where a chemical is used in multiple uses but the discharge route is the same such that the discharges of the different uses would enter the marine environment simultaneously, the chemical has been subjected to a combined assessment and only one table has been provided. For chemicals that are OSPAR Candidates for Substitution full justifications have been included: Bumi Armada have not yet submitted an annual report for the Kraken FPSO. Risk based justifications will be applied in the future when the annual chemical report is in place. 2.7 Chemical Reporting Quarterly chemical management reports are prepared by the Production Chemistry department summarising the main chemical management activities to have been completed during that quarter. The report includes performance against Key Performance Indicators relating to the use and/or discharge of chemicals. This information is then submitted to BEIS via EEMS, in line with regulatory requirements. PRA/219 CP 7

8 2.8 Chemical Summary Chemical Name Supplier HQ Chemical Label Chemical Function Group Expiry Date Template Version Bactron B2090 Nalco Ltd Gold None Biocide 25 November Cleartron ZB-584 Nalco Ltd Gold None Water Clarifier 7 October Cleartron ZB-628 Nalco Ltd Gold None Water Clarifier 28 January OS-2 Nalco Ltd E PLO Oxygen Scavenger 14 May Defoamer AF451 Nalco Ltd Gold None Antifoam (Hydrocarbons) 04 January Emulsotron CC 3344-G Nalco Ltd Gold None Demulsifier 14 November Emulsotron CC9508-G Nalco Ltd Gold None Demulsifier 15 April Emulsotron X8031 Nalco Ltd Gold O-P Demulsifier 30 July Emulsotron X-8048 Nalco Ltd Gold None Demulsifier 26 February Gyptron SA1110N-F1 Nalco Ltd Gold None Scale Inhibitor 01 April Methanol Nalco Ltd E None Gas Hydrate Inhibitor 23 September Oceanic HW 443ND Macdermid PLC D SUB Hydraulic Fluid 20 November RX-5207 Roemex Ltd E None Oxygen Scavenger 13 November RX-5227 Roemex Ltd Gold None Corrosion Inhibitor 23 April RX-9022 Roemex Ltd Gold None Pipeline Hydrotest Chemical 08 March PRA/219 CP 8

9 Chemical Name Supplier HQ Chemical Label Chemical Function Group Expiry Date Template Version RX-9034A Roemex Ltd Gold None Dye 29 April SOBO QB GOLD 08 Oil Technics Ltd Gold None Detergent/Cleaning Fluid 03 July PRA/219 CP 9

10 2.9 FPSO Commissioning Use of diesel Before the chemical lines on the new FPSO can be fully commissioned they have to be primed. Usually, this can be completed using a combination of the required chemicals and water; however, some chemicals which will be used on the FPSO are incompatible with water. As such, these lines will be primed using diesel. The diesel used will not be discharged to sea at the end of the priming operations, the diesel and any associated chemicals will be routed to the process. As a hydroca rbon, the diesel will partition with the other hydrocarbons and will be transported to shore with the crude. A record of this requirement to use diesel in the chemical lines is included for BEIS information purposes only. 3 Process Chemicals The Armada Kraken FPSO has two identical separation processes, Train A and Train B. The FPSO receives produced fluids from the four drill centres via six subsea pipelines and risers. Produced fluids are routed via director valves to Train A, Train B or the test separator. Production fluids in each train enter the FWKO drum which removes free water and gas from the received fluids. The FWKO drum in each train also receives fluids from the closed drains, slops tank, water from the off-spec water tanks and water from the sand jetting package. Gas from the production fluids is routed to the fuel gas system. Removed produced water is routed to the produced water system. The fluids leaving the vessel are then heated before entering the low-pressure (LP) separator. The LP separator also receives oily water from the produced water degasser, condensate from the low pressure gas knock-out drum and oil from the off-spec oil tank or slops tank. Removed produced water is routed to the produced water system. Hydrocarbons are sent to the electrostatic coalescer prior to being cooled and sent to the crude storage tanks. Produced water from the coalescer is also routed back to the LP separator. Produced water is again treated in two separate trains. Each train comprises: a deoiling hydrocyclone for water received from the FWKO drum and a deoiling hydrocyclone for water received from the LP separator; the water is then comingled upstream of a compact flotation unit. From the compact flotation unit (CFU), gas is routed to the produced water degasser and then the fuel gas system; any removed water returns to the CFU. The water from the CFU is routed to the produced water transfer pumps. There is an online oil in water analyser upstream of the produced water transfer pumps. At an oil in water reading of 30mg/L or above, the analyser closes the valve on the discharge to sea line and instead the water is sent to one of the two 60,000 barrel off-spec produced water tanks which in turn route back to the process upstream of the FWKO drum. On-spec produced water is routed to the fine filtration package under normal operations but there is a produced water caisson from which excess on -spec produced water from Train A and Train B can be discharged to sea. The fine filtration package preferentially uses on-spec produced water as the HSP power fluid, with any excess routed to the water injection system for injection downhole. If there is an insufficient volume of produced water for use as the HSP power fluid or to maintain reservoir support, treated seawater is used as a make-up fluid. Further details on the water injection system are presented in Section 4. However, it should be noted that the HSP and WI pumps have been designed to limit the discharge of fluids to sea: each pump have variable speed drives (VSDs) which automatically adjust the pumping rate depending on the requirements of each system. In this way the likelihood of the discharge of excess water (treated seawater or produced water or a mix of the two) is minimised. However, when either pump is started up or shut down or when the operating conditions change, there may be a sm all discharge of fluids to sea. This is because each pump must maintain a minimum flow through the pumps to prevent damage and there may be a delay in the VSD compensating for changes in the operating conditions. At time of writing, this delay is difficult to estimate but a likely volume of discharge from the pumps has been made. Details are provided in the next section. PRA/219 CP 10

11 At time of commissioning, produced water will not immediately be available for HSP power fluid or reservoir support; treated seawater may be used in the first instance and produced water increasingly used for HSP power fluid and reservoir support over time. Once all the wells are online, the HSP power fluid will be produced water only with excess produced water sent to the water injection sy stem. 3.1 CHARM On an installation which operates PWRI the standard industry assumption is that only 1% of the chemical will return over time with the produced water, as is assumed for water injection chemicals (Section 3). The worst case discharge of chemicals in the produced water will occur when the PWRI system is offline and the produced water is discharged overboard. To reflect this scenario, continuously applied process chemicals have been risk assessed using the PSO algorithm and appropriate sub-algorithms. Batch applications of process chemicals will not occur during periods of start -up or shut-down or when PWRI is offline. However an unplanned event may result in batch chemicals being discharged to sea via the produced water caisson. Such instances have been modelled using the PSO algorithm and appropriate sub-algorithms and the dosage calculated by dividing the batch size into the daily volume of appropriate fluid. There are three potential discharge routes to sea for all process chemicals: On-spec produced water will usually be routed to the fine filtration package for use as HSP power fluid and water injection, as described above. However, there is an overboard discharge produced water caisson, upstream of the fine filtration package. As chemicals which are injected downhole are subject to an assumed 1% return with produced fluids, this discharge point of produced water represents a worst environmental case and accordingly has been modelled e.g. to represent the scenario in which water injection is offline. Produced water and/or treated seawater being used in the HSP system may be released from in cases where the minimum flow through the pump is being maintained. Where necessary, a secondary risk assessment has therefore been conducted in which a batch release of four hour s worth of fluid from the pump is released to sea. The HSP pump minimum flow is 210 m 3 /hour (four hour total of 840 m 3 ). Produced water and/or treated seawater used as injection water will usually be injected downhole. However, as for the HSP pumps, there may be instances in which minimum flow must be maintained through the pump and there may be a discharge to sea. Where necessary a secondary risk assessment has therefore been conducted in which a batch release of four hours worth of fluid from the pump is released to sea. The WI pump minimum flow is 365 m 3 /hour (four hour total of 1,460 m 3 ). For several process chemical applications, the dosage of chemicals within the batch release from the WI or HSP pumps would be the same dosage as would be present in the produced water if the PWRI system was offline. The potential environmental impact of the batch release of the smaller volume of produced water chemicals via the pumps would be less than the continuous release of the larger volume of produced water when PWRI is offline therefore no supplementary risk assessment of the release from the WI or HSP pumps has been modelled in these instances. Full details are presented in the chemical tables as necessary. First oil is not expected from the field until As such, no process chemicals have been risk assessed for Risk assessments have been completed for pipeline commissioning chemicals that will be discharged from the FPSO during 2016 using the CWS algorithm. PRA/219 CP 11

12 3.2 Chemical Selection Water Clarifier Water clarifiers are required on the Kraken FPSO to assist with the separation of process fluids as an aid to the mechanical separation techniques described in Section 3. Chemical treatments promote flocculation and/or coalescence of the oil droplets into the oil phase thereby removing oil from produced water prior to discharge. Chemical name Cleartron ZB-584 Supplier Nalco Ltd Function Water Clarifier Application point Inlet of FWKO, PW outlet of FWKO, PW outlet from LP separator and upstream of the PW CFU of Train A and B Application 1 of 1 Treatment philosophy and application To ensure all recycled produced water meets an OIW specification of <30 mg/l it is likely chemical treatment will be required. Failure to meet this specification risks shutting down the produced water process, which would route produced water to the off-spec produced water tanks, resulting in production restrictions. To improve water quality it is recommended a deoiler is applied to the produced water system. Two deoiler products have been recommended for field start-up to identify the best chemistry. Both have been added to the permit for all years; however, one will be removed once the best product is identified. Cleartron ZB-584 is a water clarifier which flocculates oil droplets and suspended fluids to aid the recovery of oil from the produced water. In each production train it is continuously injected. There are multiple possible injection points which may be used as required. Although this product could mix with the oil phase depending on the injection point used, the modelling has been conducted on produced water as a worst case. The product is injected at a maximum rate of 15 ppm (19.5 product density of g/cm 3 ) at each injection point. This could result in a total dosage of 90 ppm (116.7 mg/l) so this has been used as the discharge dosage for this product. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re-injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. Year PLONOR No HQ category Gold Identified for No < <1 Fraction discharged % The product could be applied at a total dosage of 90 ppm (116.7 mg/l) based on the produced water volume. The CHARM default discharge of 100% for the PSO algorithm has been used. CHARM algorithm code PSO Discharge code CTN PRA/219 CP 12

13 The generated was <1, indicating that the discharge would not be expected to pose a significant risk to the receiving environment. Chemical name Cleartron ZB-628 Supplier Nalco Ltd Function Water Clarifier Application point Inlet of FWKO, PW outlet of FWKO, PW outlet from LP separator and upstream of the PW CFU of Train A and B Application 1 of 1 Treatment philosophy and application To ensure all recycled produced water meets an OIW specification of <30 mg/l it is likely chemical treatment will be required. Failure to meet this specification risks shutting down the produced water process, which would route produced water to the off-spec produced water tanks, resulting in production restrictions. To improve water quality it is recommended a deoiler is applied to the produced water system. Two deoiler products have been recommended for field start-up to identify the best chemistry. Both have been added to the permit for all years; however, one will be removed once the best product is identified. Cleartron ZB-628 is a water clarifier which flocculates oil droplets and suspended fluids to aid the recovery of oil from the produced water. In each production train it is continuously injected. There are multiple possible injection points which may be used as required. Although this product could mix with the oil phase depending on the injection point used, the modelling has been conducted on produced water as a worst case. The product is injected at a maximum rate of 15 ppm (16.3 product density of g/cm 3 ) at each injection point. This could result in a total dosage of 90 ppm (97.6 mg/l) so this has been used as the discharge dosage for this product. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re -injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. Year PLONOR No HQ category Gold Identified for No < <1 Fraction discharged 97.6 mg/l 100% The product could be applied at a total dosage of 90 ppm (97.6 mg/l) based on the produced water volume. The CHARM default discharge of 100% for the PSO algorithm has been used. CHARM algorithm code PSO Discharge code CTN The generated was <1, indicating that the discharge would not be expected to pose a significant risk to the receiving environment. PRA/219 CP 13

14 3.2.2 Demulsifier The primary separation of oil and water occurs in the FWKO drum as described in Section 2.9; however this is supplemented by the use of demulsifier. Demulsifiers improve the separation of water from oil which helps to improve process stability by reducing the occurrence of water in oil emulsions in the separation vessels. Demulsifiers also reduce the amount of oil entrained in the produced water in the early stages of processing, which reduces the duty required from the produced water processing train. Chemical name Emulsotron CC 3344-G Supplier Nalco Ltd Function Demulsifier Application point Upstream of the FWKO, the FWKO oil outlet and upstream of the Electrostatic coalescer of Train A and B Application 1 of 1 Application details The high viscosity of the Kraken crude oil coupled with the low reservoir temperatures has the potential to cause phase separation issues topside. Using a demulsifier will improve the control of OIW and water content of the crude oil. Three products have been recommended for field start-up based on onshore laboratory work. Following field start-up the best product will be identified and the others removed; however until confirmation of the best product all three have been applied for on this permit. In each production train Emulsotron CC 3344-G is continuously injected. There are multiple injection points which may be used as required. The product is injected at a maximum rate of 25 ppm (22.2 product density of g/cm 3 ) at each injection point. This could result in a total dosage of 150 ppm (133.4 mg/l) so this has been used as the discharge dosage for this product. This exceeds the dosage on the CEFAS template. As no crude samples are available for testing a worst case dosage has been selected for start-up. Testing will occur on start-up and the dosage will be optimised accordingly. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re -injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. Year PLONOR No HQ category Gold Identified for No < <1 Fraction discharged 100% mg/l The product is applied at a dosage of 150 ppm (133.4 mg/l) based on the total produced fluid volume The CHARM default discharge of 100% for the PSO algorithm has been used. CHARM algorithm code PSO Discharge code CTN The generated was <1, indicating that the discharge would not be expected to pose a significant risk to the receiving environment. PRA/219 CP 14

15 Chemical name Emulsotron CC9508-G Supplier Nalco Ltd Function Demulsifier Application point Production flowline Application 1 of 1 Application details The high viscosity of the Kraken crude oil coupled with the low reservoir temperatures has the potential to cause phase separation issues topside. Using a demulsifier will improve the control of OIW and water content of the crude oil. A subsea application of demulsifier has been recommended. Emulsotron CC9508-G is continuously injected into the subsea production manifold at a rate of 20 ppm (18.0 product density of 0.9 g/cm 3 ) based on the produced fluid volume. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re -injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. Year PLONOR No HQ category Gold Identified for No < < mg/l Fraction discharged 100% The product is applied at a dosage of 20 ppm (18.0 mg/l) based on produced fluid volume. The CHARM default discharge of 100% for the PSO algorithm has been used. CHARM algorithm code PSO Discharge code CTN The generated was <1, indicating that the discharge would not be expected to pose a significant risk to the receiving environment. PRA/219 CP 15

16 Chemical name Emulsotron X8031 Supplier Nalco Ltd Function Demulsifier Application point Upstream of the FWKO, the FWKO oil outlet and upstream of the Electrostatic coalescer of Train A and B Application 1 of 1 Application details The high viscosity of the Kraken crude oil coupled with the low reservoir temperatures has the potential to cause phase separation issues topside. Using a demulsifier will improve the control of OIW and water content of the crude oil. Three products have been recommended for field start-up based on onshore laboratory work. Following field start-up the best product will be identified and the others removed; however until confirmation of the best product all three have been applied for on this permit. In each production train Emulsotron X8031 is continuously injected. There are multiple injection point which may be used as required. The product is injected at a maximum rate of 25 ppm (22.7 product density of g/cm 3 ) at each injection point. This could result in a total of 150 ppm (136.2 mg/l) so this has been used as the discharge dosage for this product. This exceeds the dosage on the CEFAS template. As no crude samples are available for testing a worst case dosage has been selected for start-up. Testing will occur on start-up and the dosage will be optimised accordingly. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re-injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. Year PLONOR No HQ category Gold Identified for No < <1 Fraction discharged 100% mg/l The product is applied at a dosage of150 ppm (136.2 mg/l) based on the total produced fluid volume The CHARM default discharge of 100% for the PSO algorithm has been used. CHARM algorithm code PSO Discharge code CTN The generated was <1, indicating that the discharge would not be expected to pose a significant risk to the receiving environment. PRA/219 CP 16

17 Chemical name Emulsotron X-8048 Supplier Nalco Ltd Function Demulsifier Application point Upstream of the FWKO, the FWKO oil outlet and upstream of the Electrostatic coalescer of Train A and B Application 1 of 1 Application details The high viscosity of the Kraken crude oil coupled with the low reservoir temperatures has the potential to cause phase separation issues topside. Using a demulsifier will improve the control of OIW and water content of the crude oil. Three products have been recommended for field start-up based on onshore laboratory work. Following field start-up the best product will be identified and the others removed; however until confirmation of the best product all three have been applied for on this permit. In each production train Emulsotron X-8048 is continuously injected. There are multiple injection points which may be used as required. The product is injected at a maximum rate of 25 ppm (21.9 product density of g/cm 3 ) at each injection point. This could result in a total of 150 ppm (131.6 mg/l) so this has been used as the discharge dosage for this product. This exceeds the dosage on the CEFAS template. As no crude samples are available for testing a worst case dosa ge has been selected for start-up. Testing will occur on start-up and the dosage will be optimised accordingly. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re -injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. Year PLONOR No HQ category Gold Identified for No Fraction discharged 100% mg/l The product is applied at a dosage of 150 ppm (131.6 mg/l) based on the total produced fluid volume The CHARM default discharge of 100% for the PSO algorithm has been used. CHARM algorithm code PSO Discharge code CTN PRA/219 CP 17

18 The generated was >1, indicating that the discharge has the potential to pose a significant risk to the receiving environment. Information from the MSDS for this chemical indicates that: the product is insoluble in water and has no known ecotoxicological effects at the component level, only two components of this product exhibit toxicity to test groups at concentrations below the worst case application dosage. Of these, one component is readily biodegradable and the other, which is responsible for the worst case toxicity, is biodegradable and constitutes 32.7% of the product. Assuming the worst case discharge dosage, the effects on the marine environment would therefore be expected to be short in duration and to affect particular species. The chemical risk assessment was conducted assuming all possible injection points on both process trains would be applying the chemical continuously as a worst case; however it is more likely that a maximum of two injection points, per train (4 in total) would be used at any one time. This would reduce the application dosage to 100 ppm (87.7 mg/l). The generated for this more realistic scenario for both years returns an <1. It should also be noted, as stated above, that once crude oil samples are available to test, the application dosage of this chemical at the various injection points may be reduced Scale Inhibitor In order to achieve the necessary water injection volumes, seawater may need to be comingled with produced water. The mixing of these waters may result in the deposition of scale. The use of seawater may also result in the deposition of scale at other points of the process. As su ch, scale inhibitor is required. PRA/219 CP 18

19 Chemical name Gyptron SA1110N-F1 Supplier Nalco Ltd Function Scale Inhibitor Application point Oil/PW heat exchanger of Train A and B, HSP Power Fluid manifold and upstream of the HSP (downhole) Application 1 of 1 Treatment philosophy and application The scale risk associated with production of the Kraken formation/produced water has been evaluated to be high. In order to mitigate the risks from scale, several continuous injection points for scale inhibitor are present throughout the system in order to maintain a treatment dosage of 10 ppm (13.0 mg/l). The oil/pw heat exchanger injection point is needed as the higher temperatures present increases the risk of calcium carbonate scale forming which would reduce the performance of the heaters. When PWRI is offline treated produced water from the topside process may be discharged to sea via the produced water caisson. The HSP power fluid manifold injection point ensures that the required dosage of 10 ppm is maintained to prevent the precipitation of scale particularly when seawater and produced water are mixed for use as the power fluid. The loss of the HSP system would result in production downtime. Under normal operating conditions HSP fluid will be injected downhole or recycled within the HSP manifold; however, there may be a short-term discharge of treated HSP power fluid if operating conditions change and the HSP pump variable speed drives have to compensate. We have assumed there could be a maximum discharge of four hours worth of treated fluid from the HSP pumps; however this will release less chemical than the discharge from the PW caisson if PWRI were to be offline, therefore a supplementary risk assessment has not been conducted. The third injection point is downhole and immediately upstream of the HSP where again, a treatment dosage of 10 ppm must be maintained to protect the downhole ESDV valves. This injection point would be used as needed and is effectively an injection chemical application. As described above, the various injection points are required to maintain the 10 ppm treatment dosage. The worst case environmental scenario is that produced water is discharged overboard as opposed to being used as part of the HSP system. This has been represented in the CHARM risk assessment. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re -injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. Year PLONOR No HQ category Gold Identified for No < <1 Fraction discharged 13.0 mg/l 100% The product is applied at a dosage of 10 ppm (13.0 mg/l) based on the produced water volume. The CHARM default discharge of 100% for the PSO algorithm has been used CHARM algorithm code PSO Discharge code CTN The generated was <1, indicating that the discharge would not be expected to pose a significant risk to the receiving environment. PRA/219 CP 19

20 3.2.4 Oxygen Scavenger Chemical name OS-2 Supplier Nalco Ltd Function Oxygen Scavenger Application point HSP power fluid Application 1 of 1 Treatment philosophy and application Oxygen corrosion presents a significant risk to all HSP tubing. The deaerator tower removes a significant concentration of oxygen from lifted seawater, however a chemical application is required to meet the fluid specification. To ensure lifted seawater and recycled produced water used as HSP power fluid is suitably deaerated further chemical treatment may be required. The produced water and seawater is expected to be largely deaerated, however due to the importance of this system, the option for additional chemical treatment is requested. The chemical is injected at approximately 10 ppm based on water rate through the HSP manifold. 0% discharge will occur under steady operations, however, when the HSP pump is adapting to changing operational conditions, we have assumed that up to four hours of HSP power fluid may be discharged from the HSP pump. PLONOR Yes HQ category E Identified for No N/A N/A N/A Fraction discharged 100% N/A CHARM algorithm code CNA Discharge code CON OS-2 is OCNS E registered and is on the OSPAR PLONOR list. The quantities used and discharged at the Armada Kraken FPSO are not expected to have any significant impact on the surrounding marine environment Foam Control When reservoir fluids are lifted to the FPSO, process gas becomes entrained in the produced fluids. The gas then cools in the subsea flow lines. When depressurised in the FWKO drum, the gas becomes suspended in the fluids, producing a foam. This causes difficulties within level control vessels, reducing the efficiency of fluid separation. If untreated, this could cause a carryover of hydrocarbon fluids into the gas outlets which can damage the compressors. Antifoams are therefore required. Chemical name Defoamer AF451 Supplier Nalco Ltd PRA/219 CP 20

21 Function Antifoam (Hydrocarbons) Application point Inlet of FWKO and oil/pw heat exchanger of Train A and B Application 1 of 1 Treatment philosophy and application Kraken crude oil is known to produce a stable foam as it degasses. Given the pressure reduction present in the FWKO the potential exists to create foam. This has been confirmed by onshore screening of the crude oil. Defoamer AF451 is injected into the inlet of the FWKO drum in each train. A second injection point at the oil/pw heat exchanger will be used if necessary, to maintain the treatment dosage of 20ppm throughout the system (17.1 product density of g/cm 3 ) based on the produced fluid volume. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re -injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. Year PLONOR No HQ category Gold Identified for No < <1 Fraction discharged 17.1 mg/l 100% The product is applied at a dosage of 20 ppm (17.1 mg/l) based on total produced fluid rates. The CHARM default discharge of 100% for the PSO algorithm has been used CHARM algorithm code PSO Discharge code CTN The generated was <1, indicating that the discharge would not be expected to pose a significant risk to the receiving environment Biocide Biocide is applied to the produced water to control microbial growth and minimise the level of corrosion. The effectiveness of biocide treatments will be monitored by means of regular sampling and analysis of produced water for microbiological activity. Swabs will also be taken of any corrosion coupons on retrieval to monitor microbe build-up. Chemical name Bactron B2090 Supplier Champion Technologies Ltd Function Biocide Application point HSP Power Fluid Application 1 of 3 Treatment philosophy and application PRA/219 CP 21

22 To provide adequate microbial control in the HSP power fluid, a batch application of Bactron B2090 will be injected several times a week, depending on the volume of HSP power fluid being used. Only one batch will be applied in a single 24 hour period. A maximum batch size of 1,948 kg will be used to achieve a dose rate of 500 ppm (620 product density of 1.24 g/cm 3 ) in the power fluid. Without the use of the biocide may result in reservoir souring and major production and/or integrity issues. Under normal operating conditions HSP fluid will be injected downhole or recycled within the HSP manifold. This batch chemical is only required when fluids are circulating to the WI and HSP infrastructure. Should these systems be offline, there is no reason to treat the fluids to protect against reservoir souring hence the chemical would not be used during this time and it would not be discharged during periods of minimum flow discharge from either the WI or HSP pumps. Accordingly, the risk assessment for this chemical reflects a downhole (PIO) disposal route. Year PLONOR No HQ category Gold Identified for No < <1 Fraction discharged 620 mg/l 1% The target treatment dosage for the HSP fluid is 500 ppm (620 mg/l) The CHARM default discharge of 1% for the PIO algorithm has been used Batch dilution factor Batch use CHARM standard BDF for PIO chemicals used. 1,948 kg A maximum batch of 1,948 kg will be used 2-3 times per week. CHARM algorithm code PIO Discharge code BAT The generated was <1, indicating that the discharge would not be expected to pose a significant risk to the receiving environment. PRA/219 CP 22

23 3.2.7 Gas Hydrates Chemical name Methanol Supplier Nalco Ltd Function Gas Hydrate Inhibitor Application point Wellhead Application 1 of 1 Treatment philosophy and application Hydrate risk within the subsea infrastructure of the Kraken field is relatively low and the HSP power fluid will maintain subsea temperatures at approximately 50 C, however if a blockage occurs there is limited access to the production wellheads and methanol may be required to resolve any hydrate issues. A batch use of 395 kg once per week has been assumed as a worst case. The Kraken FPSO is planned to operate with 0% discharge of produced water. All produced water will be re -injected into the reservoir via the PWRI or used as power fluid for the HSP system. However, as a worst case it has been assumed the produced water may be discharged via the produced water caisson. PLONOR Yes HQ category E Identified for No N/A Fraction discharged N/A 100% N/A A worst case discharge of 100% via the produced water system has been assumed. Batch dilution factor Batch use N/A 395 kg N/A Batch sizes of up to 395 kg are assumed to be applied once a week as a worst case CHARM algorithm code CNA Discharge code BAT Methanol is OCNS E registered and is on the OSPAR PLONOR list. The quantities used and discharged at the Armada Kraken FPSO are not expected to have any significant impact on the surrounding marine environment. PRA/219 CP 23

24 4 Seawater Uplift and Water Injection HOLD: required chemicals are currently under review and as such this permit will be updated once the information is available. 5 Utility Chemicals Various utility chemicals are required on the Armada Kraken FPSO. These applications are described below. 5.1 CHARM The closed drain system is completely segregated from the open drains system. The non-hazardous and hazardous open drain fluids are directed to the slops tank. In the slops tanks hydrocarbons are separated by gravity and the hydrocarbons flow over a weir into the hydrocarbon compartment from where they re-enter the process upstream of the LP separator. The remaining water phase is pumped to a dedicated slop water treatment package to reduce the oil content further, allowing the water to be disch arged to sea. The frequency with which fluids will be discharged from the slops tanks will vary depending on a variety of conditions; however the duration of the release from the slops tanks will not exceed 24 hours. The batch discharge from the slops tank to sea is 1,000m 3. The closed drain fluids collect in the closed drains drum from where they are routed to one of the two FWKO drums under normal operations. There is also an option to route these chemicals to the slops tank to mingle with the open drain fluids, if necessary. Detergents and cleaning fluids that enter the open drains system will therefore be discharged overboard. As a worst case it has also been assumed that any fluids from the closed drain system will be routed to the slops tank and hence overboard. The CWS algorithm has been used to model these discharges, with a fraction released of 100%. The volume and rate of release from the slops tanks is not represented in the BDF table of the CHARM User Guide (version 1.4) so for the risk assessment a worst case discharge with a batch wise dilution factor of 4.26E-04 (density of discharged fluid = 1.03 g/cm 3, volume = 3 m 3 and discharge rate = 60 m 3 /hr) is used. 5.2 Chemical Selection Biocide Biocide is applied routinely (2-3 times per week) to the closed drains to control the growth of Sulphate Reducing Bacteria (SRB) and minimise the level of corrosion. As described above, fluids from the drains system are directed to the slops tank treatment package where hydrocarbons are removed prior to discharge. Once the level in the slop tank reaches approximately half of the capacity, the contents are sent to the treatment package before being batch - discharged. The discharge volume is approximately 1,000m 3. The residence time of the fluids in the slops tank and the frequency of the batch releases from the slops tank treatment package depends upon the volume of fluids entering the slops tanks. The residence time of the fluid in each tank depends on the volume of water entering the system. Only a proportion of the slops tank is batch discharged at any one time to ensure that fluids remain in each slops tank for a sufficient period to allow separation of the water and hydrocarbons present. Chemical name Bactron B2090 Supplier Nalco Ltd Function Biocide Application point Closed Drains system PRA/219 CP 24

25 Application 2 of 3 Treatment philosophy and application To provide adequate microbial control within the topsides production system, all drain vessels and associated lines must receive biocide treatments on a routine basis. Drains systems are at higher risk of microbial growth due to the potential for stagnant fluids and the presence of oxygen. Fluids entering the closed drains system will usually be recycled into the production system upstream of one of the two FWKO drums in either Train A or Train B. The closed drains fluids may provide a food stock for proliferation within the production vessels. To ensure this is controlled, routine batch biocides treatment of the drains/slops system has been recommended 2-3 times per week. The target dosage of this chemical is 500 ppm (620 mg/l) in the closed drains system resulting in a maximum batch size of 21 kg. In order to calculate the discharge dosage, the batch size has been diluted into one half of one day s total fluid s (Train A and Train B each have 50% capacity). Year PLONOR No HQ category Gold Identified for No < <1 Fraction discharged Batch dilution factor 2.0 mg/l (2017) 1.5 mg/l (2018) 100% The maximum batch size of 21 kg has been diluted into ½ of the produced fluids volume per day as the closed drains fluids will either enter the Train A FWKO or the Train B FWKO drum. The CHARM default discharge of 100% for the PSO algorithm has been used. As the product will enter the production system the CHARM default BDF for production chemicals has been used. Batch use 21 kg A batch size of 21 kg is applied 2-3 times per week CHARM algorithm code PSO Discharge code BAT Chemical name Bactron B2090 Supplier Nalco Ltd Function Biocide Application point Open hazardous/open non-hazardous drains Application 3 of 3 Treatment philosophy and application To provide adequate microbial control within the topsides production system, all drain vessels and associated lines must receive biocide treatments on a routine basis. Drains systems are at higher risk of microbial growth due to the potential for stagnant fluids and the presence of oxygen. PRA/219 CP 25