V11 Produced Water

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Shell Nigeria Exploration and Production

Company Ltd.

Bonga FPSO

Plant Operating Procedures Manual

Volume 11

PRODUCED WATER TREATMENT SYSTEMS

OPRM-2003-0311

Version: 1.2

This document is not confidential.

The Copyright of this document is vested in Shell Nigeria

Exploration and Production Company Limited. All rights reserved.

Neither the whole nor any part of this document may be

reproduced, stored in any retrieval system or transmitted in any

form or by any means (electronic, mechanical, reprographic,

recording or otherwise) without the prior written consent of the

copyright owner.

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Document Status Information

1.0. DOCUMENT CONTROL

1.1. Change History

Date Version Author Ref

Indicator Change Description

01/03/04 1.0 ODL – Issue of document for

signature.

31/08/05 1.1 ODL – Amendments to:

• Preliminary Pages • Part 1 Section 2 Paragraphs 3.4.2 and 4.0 Part 2 Section 1: • Procedure No 1/001 removed

• Pre-start Checks Steps 1 and 5 altered and

addition to Step 2 • Cold Start-up Steps 2

and 3 removed. Steps 6, 7, 10 and 16 altered, Step 11 added. • Procedure No 1/005 ERS 2 altered Part 2 Section 3 Hydrocyclone Back-flushing Procedure No 3/002 title ‘ Manual Backwash’ added and Automated Backwash Steps 1 to 9 added.

30/04/06 1.2 ODL/SNEPCO – Amendments throughout to address outstanding HOLDs and to reflect the final as-built P&IDs.

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2.0 PURPOSE

The purpose of this document is to provide guidance on the safe, efficient and environmentally aware operation of the Produced Water Treatment Systems.

It is one Volume within an overall suite of Volumes which comprise the Bonga FPSO Plant Operating Procedures Manual (POPM). The full listing of Volumes is as follows:

Volume 1 Field and Facilities Overview Volume 2A Subsea Production System Volume 2B Subsea Waterflood System Volume 2C Subsea Control System Volume 2D Flow Assurance Guidelines Volume 3 Oil Separation and Treatment

Volume 4 Oil Storage, Handling and Ballast Systems Volume 5 Oil Metering and Export System

Volume 6 Vapour Recovery Compression System Volume 7 Field Gas Compression System

Volume 8 Gas Dehydration/Glycol Regeneration Systems Volume 9 Gas Export/Import/Lift Systems

Volume 10 Flare and Vent Systems

Volume 11 Produced Water Treatment Systems Volume 12 Waterflood System

Volume 13 Chemical Injection and Methanol Injection System Volume 14 Fuel Gas System

Volume 15 Heating Medium System Volume 16 Drainage Systems

Volume 17 Sewage Treatment Systems

Volume 18 Bilge and Oily Water Separation Systems Volume 19 Inert Gas System

Volume 20 Nitrogen Generation System Volume 21 Seawater System

Volume 22 Fresh and Potable Water Systems Volume 23 Diesel Fuel System and Incinerator Volume 24 Aviation Fuel System

Volume 25 Instrument and Utility Air System Volume 26 Deck Hydraulic Systems

Volume 27 Fire Protection Systems and Equipment Volume 28 Safety and Lifesaving Equipment

Volume 29 PSCS and ESS

Volume 30 Power Generation and Distribution Systems Volume 31 Black Start Procedures

Volume 32 HVAC Systems

Volume 33 Deck Machinery and Mechanical Handling Systems (Cranes, etc) Volume 34 Telecommunications

Volume 35 Ancillary Living Quarters (ALQ)

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Shell Nigeria E & P Company Ltd. Unrestricted

3.0 SCOPE

This document provides a detailed description of the plant and equipment which comprise the Produced Water Treatment Systems and includes step-by-step guidance on the operation of the system and its equipment, under both normal and abnormal operation.

4.0 TARGET READERSHIP

All SNEPCO staff, contractors and other third-party personnel who may be involved in the operation of the Produced Water Treatment Systems onboard the

Bonga FPSO.

5.0 SPECIAL NOTE

Not applicable.

6.0 ABBREVIATIONS

The abbreviations used within this document are listed at the end of these introductory pages.

7.0 REFERENCE INFORMATION/SUPPORTING DOCUMENTATION

The primary reference/supporting documents, which have been either used or referred to in the development of this document, are listed at the end of these introductory pages. These are part of the available Operational Documentation, which SNEPCO Offshore Operations (OO) has in place to support its day-to-day operations. These and many other documents are available within the SNEPCO Livelink System. Where appropriate, these documents have been cross-referenced within this document.

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Abbreviations

AC Alternating Current

ACB Air Circuit-breaker

AEP Authorised Electrical Person

ANSI American National Standards Institute API American Petroleum Institute

BA Breathing Apparatus

bara Bar Absolute

barg Bar Gauge

BASEEFA British Approvals Service for Electrical Equipment in Flammable Atmospheres

BBL Barrel

BOPD Barrel of Oil per Day BPD Barrels per Day

BS&W Base Sediment and Water BWPD Barrel of Water per Day CCR Central Control Room

CEP Competent Electrical Person CI Chemical Injection

CT Current Transformer

CIV Chemical Injection Valve CV Production Choke Valve

DC Direct Current

DCS Distributed Control System

DE Drive End

DO Digital Output

DPR Department of Petroleum Resources ECP Engine Control Panel

ESR 1 Process Shutdown

ESR 2 Surface Process Shutdown ESR 3 Total FPSO Shutdown ESS Emergency Support System F&G Fire and Gas

FBHP Flowing Bottomhole Pressure

FC Fail Closed Valve

FCV Flow Control Valve FG Flow Indicating Gauge FIC Flow Indicating Controller FLA First Line Ashore

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FO Fail Open Valve

FPSO Floating Production, Storage and Offloading

FS Fuse Switch

FT Flow Transmitter

FTP Flowing Tubing Pressure FZA Flow Safety Alarm

GA General Alarm

GOR Gas/Oil Ratio

GT Gas Turbine

H High Alarm

HH High Trip

HCU Hydraulic Control Unit HCV Hand Control Valve HMI Human Machine Interface HOV Hand Operated Valve

HP High Pressure

HPI High Performance Insulation HPU Hydraulic Power Unit

HSE Health, Safety and Environment

HV High Voltage

HVAC Heating, Ventilation and Air Conditioning

Hz Hertz (Frequency)

ID Internal Diameter

IGF Induced Gas Flotation IGG Inert Gas Generator IGV Inlet Guide Vane IP Intermediate Pressure IS Intrinsically Safe

ISO International Standards Organisation

kW Kilowatt

L Low Alarm

LAT Lowest Astronomical Tide

LC Locked Closed

LCV Level Control Valve LEL Lower Explosive Limit

LG Level Gauge

LIC Level Indicating Controller

LL Low Trip

LO Locked Open

LOS Line of Sight

LP Low Pressure

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LPG Liquified Petroleum Gas

LS Level Switch

LSA Load-shed Application LSA Low Specific Activity (Scale)

LT Level Transmitter

LV Low Voltage

LZA Level Safety Alarm MOV Motor Operated Valve

m/s Metre per Second

MSDS Material Safety Datasheets

MW Megawatt

m3 _{Cubic Metres}

MAC Manual Alarm Callpoint MCC Motor Control Centre

MCCB Moulded Case Circuit-breaker MEG Mono Ethylene Glycol

MGPS Marine Growth Prevention System MIS Management Information System MIV Methanol Injection Valve

MMSCFD Millions of Standard Cubic Feet per Day

NB Nominal Bore

NC Normally Closed

NDE Non-drive End

NDT Non-destructive Testing NGL Natural Gas Liquid

NO Normally Open

NPSHA Net Positive Suction Head Available

NRV Non-return Valve

O/A/S Off/Auto/Start

OD Outside Diameter

OID Operator Interface Display OLI On-line Inspection

P&ID Piping and Instrument Diagram PCF Permit Control Facility

PCV Pressure Control Valve PDR Pressure Difference Ratio PDS Differential Pressure Switch PDT Differential Pressure Transmitter PFD Process Flow Diagram

PFS Programming Functional Specification

PG Pressure Gauge

PIC Pressure Indicator Controller

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PIV Pigging Isolation Valve PM Production Manifold PMV Production Master Valve

PPE Personnel Protective Equipment ppm v/v Part per Million by Volume ppm wt/wt Parts per Million by Weight

PSCS Process Safety and Control System

PSD Process Shutdown

PT Pressure Transmitter

PTW Permit to Work

PZA Pressure Safety Alarm

RV Relief Valve

RVP Reid Vapour Pressure RTJ Ring Type Joint

SCSSV Surface Controlled Subsea Safety Valve SCU Subsea Control Unit

SDV Shutdown Valve

SI Statutory Instrument

SI Switchgear and Instrumentation Sm3_/hr _{Standard Cubic Metres per Hour}

SPM Single Point Mooring

SRB Sulphate-reducing Bacteria SSDS Safety Shutdown System SWL Safe Working Load SWP Safe Working Pressure SWV Sacrificial Wing Valve TCV Temperature Control Valve TDS Total Dissolved Solids TEG Tri-ethylene Glycol

TG Temperature Gauge

TIC Temperature Indicating Controller T/T Tangent to Tangent (Vessel Length) TT Temperature Transmitter

TVP True Vapour Pressure TZA Temperature Safety Alarm UCP Unit Control Panel

UEL Upper Explosive Limit

UF Under-frequency

UPS Uninterruptible Power Supply

USD Unit Shutdown

UV Ultraviolet

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VCB Voltage Circuit-breaker VDC Video Display Computer VDU Visual Display Unit VFC Vacuum Fused Contactor VFD Variable Frequency Drive VRU Vapour Recovery Unit

VT Voltage Transformer

WHRU Waste Heat Recovery Unit

WI Water Injection

WI WOBBE Index

WSV Well Switching Valve

XOV Crossover Valve

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Reference Information/Supporting Documentation

Project Data

Document No/Ref Document Title

BON-AME-3PP-B-01043-001-A01

Operator Guide Produced Water System (System 43) BON-AME-3PP-B-21423-002-C06 P&ID LP Separator BON-AME-3PP-B-21423-003-C06 P&ID LP Separator BON-AME-3PP-B-21423-007-C06

P&ID Bulk Oil Treater

BON-AME-3PP-B-21443-001-C06

P&ID Produced Water Tank and Pumps

BON-AME-3PP-B-21443-002-C06

P&ID Hydrocyclone

BON-AME-3PP-B-21443-003-C06

P&ID Induced Gas Flotation Separator

BON-AME-3PP-B-21448-001-C06

P&ID Closed Drain and Overboard Header

BON-AME-3GN-B-25082-012-A01

Sheet 1 of 1

Cause and Effect Diagram Produced Water System (System 43)

BON-AME-3GN-B-25082-004-C02

Sheet 1 of 1

Cause and Effect Diagram LP Production System (System 23)

Vendor Data

Vendor Document Number Document Title

Baker Process Production and Refining

P237-H-002 Volume 1 of 1

Technical Maintenance Manual for Induced Gas Flotation Vessel

P237-H-004 Volume 1 of 1

Technical Maintenance Manual for De-oiling Hydrocyclone

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Sulzer Pumps P0001/29/M008/00 1

Sulz-088-340

Technical Manual (Installation, Operation and Maintenance)

P237-M-500 Volume 1 of 1

Datasheets for the

Hydrocyclone Vessel S-4340 Baker Process Production

and Refining

P237-M-501 Volume 1 of 1

Datasheets for the IGF Separator V-4341

HEMP Actions

No Description Control Measure ODL Action

1 Valve alignment of

produced water out of the LP Separators, incorrect listing of valves.

Update POPM with correct valve alignment and valve numbering, ensure latest available revision of the documentation is available prior to writing of POPM.

Procedure No 1/001 Cold Start-up Valve table amended.

2 Priming and starting of produced water pumps – confusion due to

statement of cracking open suction SDV and starting of pump with closed discharge valve. Could pre-filling of piping be a better option?

The discharge valve is a CSO valve.

Input more information to the POPM concerning type of pump and specific start-up sequence.

Procedure Nos 1/001 and 1/002 amended.

3 Charging of the system with seawater prior to start-up, POPM is vague as to the management of the operation.

Specific description of the operation to be detailed in the POPM. Added to pre-start checks in Procedure No 1/001. 4 Start-up of oil-in-water analysis is not specific as to when system should be placed in operation.

More detail required in the procedures.

Amended in Procedure Nos 1/001 and 1/002.

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HAZOP Actions

Action

Number/ Node

Node Description Response to HAZOP Operation Procedure Section/Procedure 290/6.0

3

Produced Water Hydrocyclones

Carry out routine back-flushing once per shift.

Part 2 Section 3 Procedure No 3/002. 130/17 Induced Gas Flotation Separator Methanol from production process passing overboard with the produced water.

Text and references added to Part 1 Section 1 Paragraph 3.3.

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OPRM-2003-0311 Page xiv of xiv 30-April-2006

Main Table of Contents

Document Status Information

Abbreviations

Reference Information/Supporting Documentation

Part 1 – Technical Description

Section 1 System Overview

Section 2 Detailed Description

Part 2 – Operating Procedures

Section 1 System Operating Procedures

Section 2 Equipment Operating Procedures

Section 3 Supplementary Operating Procedures

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Shell Nigeria E&P Company Ltd. Unrestricted

PART 1 TECHNICAL DESCRIPTION

Section 1 System Overview

Section 2 Detailed Description

Part 1 Technical Description

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Part 1 Technical Description

Section 1 System Overview

1.0 INTRODUCTION

All produced water extracted from the Bonga well fluids by the Oil Separation and Treatment System is processed by the Produced Water Treatment System. The produced water treatment facilities ensure the quality of the water discharged to sea meets the required standard of 15ppm (wt) from a maximum inlet hydrocarbon concentration of 1000ppmv.

The Produced Water Treatment System consists of the following major components: • Produced Water Tank V-4340

• Produced Water Pumps P-4340A/B • Produced Water Hydrocyclone S-4340

• Induced Gas Flotation (IGF) Separator V-4341

The system is currently rated to process 100,000BWPD of produced water but is designed to accommodate future expansion of up to 160,000BWPD.

2.0 PROCESS

DESCRIPTION

Refer to Figure 1.1.

The produced water leaving the Oil Separation and Treatment System contains too high a concentration of oil for dumping at sea, and is therefore treated by passing the fluid through the Produced Water Treatment System.

Produced water separated in the LP Separators V-2341A/B and Bulk Oil Treater V-2343 enters the Produced Water Tank V-4340 under the interface level control of these vessels. The combined incoming flow passes into a 20in inlet manifold and mixes with any clean produced water recycled from the hydrocyclone.

Dosing points for the injection of water clarifier and scale inhibitors are located on the produced water outlets from the LP separators.

Produced Water Tank V-4340 is a vertical, two-phase vessel designed to remove dissolved hydrocarbon gases from the incoming produced water. The vapours are released to the first-stage VRU suction scrubber. The produced water tank operates at low pressure to maximise hydrocarbon vapour recovery to the VRU compressor. Degassed produced water is passed from the tank to the suction of the 100% capacity Produced Water Pumps P-4340A/B. The duty pump discharges the produced water to Hydrocyclone S-4340. The produced water pumps are specifically designed to limit the shearing effect on any oil droplets in the produced water, so as not to adversely affect the oil removal efficiency in the hydrocyclone. The produced water pumps are protected against operating below the minimum flowrate by a recycle line. When the discharge flow falls below the minimum set point, a recycle flow control valve opens to recycle water from the pump discharge back to the produced water pump.

There is provision to install a third produced water pump (P-4340C) at a later date when the water cut of the Bonga reservoir fluids has increased to a point where the existing capacity of the Produced Water Treatment System is exceeded.

Produced Water Hydrocyclone S-4340 consists of a single hydrocyclone unit, which contains a number of individual hydrocyclone tubes (normally referred to as hydrocyclone liners).

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There is provision to install a second produced water hydrocyclone (S-4341) to process the extra produced water in the future.

In the hydrocyclone unit the oil droplets suspended in the produced water are separated from the water by enhanced gravity separation and leave the hydrocyclone through three individual oil reject lines to a common oil reject header for re-processing in the production sump. The denser water phase exits the hydrocyclone at about 40ppm (wt) and discharges into a clean water outlet header. Clean water from the hydrocyclone is directed to Induced Gas Flotation Separator V-4341, which further reduces the oil-in-water concentration until it is within the required specification of 15ppm (wt) total.

A chemical injection point is provided on the clean water outlet from the hydrocyclone so as to enable water clarifier to be injected to the induced gas flotation separator, if required. The addition of this chemical encourages bonding of the small oil droplets to enhance the performance of the IGF separator.

The induced gas within the IGF separator assists the upward velocity of the oil droplets to float to the surface as a foam, where they are skimmed off and directed to the production sump. Hydrocarbon gas is vented from the IGF separator to the first-stage VRU suction scrubber.

Clean, degassed produced water is discharged to the sea from the IGF separator, under level control. An oil-in-water analyser is provided for monitoring the produced water being dumped overboard. This is located on the downstream pipework of the IGF separator and will alarm to indicate a high level of oil-in-water content.

Final disposal of the produced water takes place through the overboard header and caisson to the sea.

Off-spec produced water which cannot be dumped to sea is switched to the slop oil tank or the primary reception tank.

3.0 HEALTH, SAFETY AND ENVIRONMENT (HSE)

3.1 General

The Produced Water Treatment System is located on the vessel topsides and as such forms part of the main topside operating area.

All personnel in the area must have received training in, and be fully conversant with, the following:

• Location and use of fire and safety equipment in the area

• Recognition and response to all the vessel’s visual and audible alarms • Muster and evacuation procedures

• Escape routes

• Location and use of lifesaving equipment

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3.2 Specific

Hazards

The Produced Water Treatment System handles mainly produced water at relatively low temperature (50°C) and pressure. Therefore, hazards are low compared with other processing systems. However, it is incorrect to assume that no hazards exist. Potential hazards include the following:

• The produced water tank is gas blanketed

• Level control problems in the LP separators or oil treater could result in large quantities of oil reaching the produced water tank

• Level control problems in the LP separators could result in gas blowby, with large volumes of gas flowing to the produced water tank

This system cannot be taken for granted just because it usually contains mostly water.

All personnel must wear the appropriate protective clothing (overalls, safety helmet, gloves, goggles etc) when in the area, and wear hearing protection if noise levels in the area are high.

The Produced Water Treatment System employs various items of rotating equipment which must have all moving parts securely guarded at all times.

3.3 Environmental

Issues

3.3.1 Overboard Discharge

Since the Produced Water System discharges effluent overboard, environmental issues could arise if the discharge fails to meet the required discharge parameters. However, the final effluent is automatically monitored and if its quality deteriorates below the allowable value, the off-specification water is automatically diverted for further treatment. Diverted water will usually be routed to the dirty slops tank. From there it will be pumped to the LP separator for reprocessing. Refer to Volume 2 Subsea Facilities, Flowlines and Risers for details.

3.3.2 Low Specific Activity (LSA)

Naturally Occurring Radioactive Material (NORM) is found throughout the natural environment, including reservoir formations. Formation water (ie produced water) dissolves radioactive salts from the formation rock and brings NORM to the surface with the produced water. The activity concentration of this NORM contamination is very low, and to emphasise that the concentrations are very low, such material is usually referred to as LSA.

Since the levels are typically very low, LSA in produced water is not a problem, unless it becomes concentrated in some manner. As the produced water is subjected to changes in temperature and pressure during the treatment process, dissolved solids may precipitate out of solution and deposit scale and sediment (sludge). Sludge and scale wastes should be removed from production equipment in a safe and controlled manner, and disposed of in a manner that complies with local regulations.

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3.3.3 Methanol in Produced Water

Methanol injected at the crude oil wells, flowlines and topsides process facilities appears in the produced water. Methanol biodegrades in water, however methanol in high concentrations (>1%) in fresh or salt water can have harmful effects on aquatic flora and fauna within the immediate discharge area.

Under current environmental guidelines and standards for the Petroleum Industry in Nigeria (revised edition 2002) issued by the Department of Petroleum Resources (DPR), methanol discharge from offshore structures is currently unregulated. However, in line with best practice, methanol discharge from Bonga should be kept as low as reasonably practicable.

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Figure 1.1 – Produced Water System Overview

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Part 1 Section 2 Detailed Description

OPRM-2003-0311 Page 1 of 18 30-April-2006

Part 1 Technical Description

Section 2 Detailed Description

1.0 INTRODUCTION

The Produced Water Treatment System removes the traces of oil from the water which has been produced with the crude oil from the Bonga formation and undergone separation in the LP separators and bulk oil treater. After treatment, the clean water is discharged overboard.

Major items in the Produced Water Treatment System are as follows: • Produced Water Tank V-4340

• Produced Water Pumps P-4340A/B • Produced Water Hydrocyclone S-4340

• Induced Gas Flotation (IGF) Separator V-4341

2.0 EQUIPMENT

DETAILS

2.1 Produced

Water

Tank

Equipment Details

Tag Number: V-4340

Location: Port Process Module Manufacturer: IMS

Design: Welded steel with vertical support Design Temperature: -10°C to 94°C

Design Pressure: +1.034barg/-0.052barg Capacity: 729.0m3/hr

Refer to Figure 2.1 or P&ID BON-AME-3PP-B-21443-001-C066.

Equipment Description

The purpose of Produced Water Tank V-4340 is to collect produced water from the LP separators and bulk oil treater operating at pressures ranging from 20.0barg to 2.4barg, and to provide safe disposal to the first-stage VRU suction scrubber of gases liberated by the pressure reduction in the vessel to 0.5barg.

Because the produced water tank is fed with produced water by process vessels at different pressures, emulsification and oil droplet dispersion may occur in the vessel. Consequently, the size of the next downstream vessel, Induced Gas Flotation Separator V-4341, has been designed to give a long residence time to aid the break-up of emulsions.

Produced Water Tank V-4340 is a vertically mounted vessel which measures 5.486m in diameter and 5.586m in height (tan/tan). The internal surfaces of the tank are epoxy lined to avoid corrosion. The tank has a design pressure of +1.034/-0.052barg, a temperature range of -10 to +94°C and is sized for the future produced water flowrate of 160,000BWPD.

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Produced water enters at the top of the tank through a 20in flanged nozzle. The fluid is directed through an internal drop line to the bottom of the tank where it is distributed through a series of 25mm x 230mm slots to minimise splatter. This process, together with the drop in pressure, encourages dissolved hydrocarbon gases to flash-off.

Under normal operating conditions the pressure in the produced water tank is not allowed to exceed 0.5barg, with make-up gas directed through 32-PCV-001 to the tank as necessary. Vacuum Breaker 43-PSV-303, which is set at -26mbarg provides protection against vacuum conditions.

The produced water tank is designed to counteract the adverse effects of FPSO motion, and operates as a two-phase separation vessel approximately half liquid full, with 4 minutes hold-up time between high and low alarm points.

Any separated oil droplets float on top of the water and form a layer over a period of time. Provision is made to drain off or ‘skim’ any such accumulations of oil in the vessel by means of 10 individual valved tappings over the operating range of the vessel with 6in spacing. The tappings are arranged in two groups of five each with a manifold, leading to two tundishes. Skimmed oil is disposed of from each tundish to the Collection Sump S-4701B.

Level Gauges 43-LG-302A and B allow constant monitoring of the level inside the tank. An overflow line is hard piped from the produced water tank to the dirty slops tank.

Degassed produced water flows through a vortex breaker from the tank to the Produced Water Pumps P-4340A/B.

2.2 Produced

Water

Pumps

Tag Number: P-4340A/B

Location: Port Process Module

Manufacturer: Sulzer Pumps

Model: VCR 10-14-24A/6 Stage

Driver Rating: 350kW

Voltage: 6.6kV Suction Pressure: 0.5barg

Discharge Pressure: 12.1barg Capacity: 662.5m3_/hr

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The produced water pumps are required to raise the pressure of the degassed produced water from Produced Water Tank V-4340 up to 12barg. This is the required pressure to drive the fluids through the hydrocyclone.

There are two identical pump sets provided, one dedicated for duty and the other as standby. The manufacturer of the pump sets is Sulzer Pumps.

The produced water pumps are low speed, low sheer, vertical canister pumps, which are specifically designed to limit the shearing effect on any oil droplets in the produced water, so as not to adversely affect the oil removal efficiency in the downstream hydrocyclone. A removable strainer is provided on the produced water pump suction to protect the pump from debris.

The pump has six stages and is driven through a Kopflex, disc type, spacer coupling by a 350kW electric motor.

The pump bowl is supported by the discharge column, which also houses the line shaft drive to the impellers. At the top of the discharge column is the suction and discharge head, which allows connection of the lines to and from the pump. The suction connection directs produced water into the canister from where the pump draws the fluid. Draining of the suction can and pump casing is achieved by pressurising the suction can with nitrogen.

The electric motor driver is mounted vertically upon the suction and discharge head. Produced water leaves the discharge column through an elbow to the discharge nozzle. The line shaft penetrates the elbow to connect to the driver, with containment provided by a John Crane single-cartridge mechanical seal.

Each produced water pump has a capacity of 662.5m3_{/hr (100,000BWPD).}

Produced water exits the discharge of the duty pump and is directed to Produced Water Hydrocyclone S-4340.

The duty pump operates continuously at a constant throughput with Flow Control Valve 43-FCV-321 regulating the discharge flow through a recycle line, from downstream of the hydrocyclone, back to the inlet header for the produced water tank.

2.3 Produced

Water

Hydrocyclone

Tag Number: S-4340

Manufacturer: Baker Process Production and Refining Model: M1150-Km-300# Operating Weight: 7710kg

Design Temperature: -10°C to 94°C Design Pressure: 24.1barg Inlet Oil Concentration: 1000ppm Outlet Oil Concentration: <40ppm

Capacity: 168.9m3_{/hr (minimum) to 662.5m}3_{/hr (maximum)}

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The hydrocyclone is manufactured to a proprietary design marketed under the trade name of ‘Vortoil’ and consists of four main sections:

• Involute inlet chamber • Concentric reducing section • Fine tapered section

• Parallel section

Produced Water Hydrocyclone S-4340 consists of a single hydrocyclone pressure vessel, which contains 241 individual hydrocyclone liners and 30 blanks to permit upgrade for a throughput of 110,000BWPD.

The liners operate in parallel inside the vessel and can be added or removed, and blanked internally to adjust capacity whilst maintaining the required flow through each liner, thereby allowing fine tuning of the hydrocyclone. All hydrocyclone liners are fed from a common inlet nozzle, and each hydrocyclone liner discharges into a common clean water outlet header. The reject oil from each liner is piped individually to a manifold, which has a common outlet for the reject stream.

Driven by the system pressure of 12.1barg (ie produced water pump discharge pressure), the oily water mixture enters each hydrocyclone liner via a tangential inlet to form a vortex. On entering the inlet of the hydrocyclone liner, the produced water undergoes virtually instantaneous separation of oil and water due the cyclonic forces imparted.

Forced down the liner, the fluid is accelerated in the concentric reducing section thus inducing high centrifugal forces. The denser water phase moves outwards passing down the liner and exiting at the clean water outlet, while the lower density oil is drawn into the low pressure core. This last section provides increased residence time for smaller, slower oil droplets to migrate to the core.

Note: The minimum flowrate is 2.0m3_{/hr per liner. Below this flowrate the centrifugal}

forces inside the hydrocyclone are too weak to provide efficient separation.

The combination of the back-pressure applied to the clean water outlet (controlled by 43-LCV-301A) and the lower reject pressure (controlled by 43-PDCV-325) causes reverse flow to be induced in the central oil core. The oil reject leaves the hydrocyclone liner through an orifice centrally positioned in the back wall of the involute chamber at the top of the liner.

The clean produced water from the hydrocyclone passes to the induced gas flotation separator, and the rejected oil stream is directed to the production sump.

Limitations on the use of hydrocyclones are as follows:

• The flow through the hydrocyclone must be within the recommended operating range

• The oil-in-water of the feed should not exceed the design limit of 1000ppm • There should be no device upstream of the hydrocyclone which could reduce

droplet size or form emulsions. If small hydrocarbon droplets (ie less than 15 microns) are present in the produced water, a chemical such as polyelectrolyte should be introduced upstream of the hydrocyclone to encourage bonding of the small droplets

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In the pipework associated with the hydrocyclone there is a facility to direct produced water from the inlet stream to the reject oil line in order to back-flush the orifice in the reject oil outlets. This facilitates backwashing the holes in the reject plates should they become blocked.

Relief Valve 43-RV-323 provides overpressure protection for the hydrocyclone chamber from a blocked-in thermal/fire condition. This RV is set to relieve to the production relief header at a pressure of 24.1barg.

Relief Valves 43-RV-347A/B, located on the clean produced water header, provide liquid overpressure protection for the induced gas flotation separator. The relief valves are set to relieve to the slop oil or primary reception tank at a pressure of 1.05barg.

2.4 Induced Gas Flotation Separator

Tag Number: V-4341

Manufacturer: Baker Hughes Production and Refining Design: ASME VIII DIV 1 1998 + 2000 Addenda Operating Weight: 120,320kg

Design Temperature: -10°C to 93.3°C

Design Pressure: 1.049barg/Full Vacuum Inlet Oil Concentration: 300ppm (maximum) Outlet Oil Concentration: <15ppm

Capacity: 662.4m3_/hr

Refer to Figure 2.3 or P&ID BON-AME-3PP-B-21443-003-C064.

Induced Gas Flotation Separator V-4341 is a single horizontal depurator vessel consisting of three compartments in series where further recovery of oil not removed by the hydrocyclone takes place. The unit measures 3024mm in width and 11,328mm tan to tan.

The first and second compartments are sub-divided into two cells, each with a 15kW motor-driven rotor mechanism (stirrer/agitator) surrounded by a dispenser, draft tube and standpipe arrangement. These facilities are fitted with blanket gas intake ports to induce gas into the produced water.

‘Clean’ produced water from the upstream hydrocyclone enters the IGF separator, passes through an underflow baffle and enters the first compartment where the entrained oil is removed by the action of the rotation mechanism and the induction of blanket gas in each of the two cells. The rapid rotation of the rotor forms a liquid vortex which extends from the standpipe to just above the tank bottom. This generates a static pressure reduction, resulting in a natural ingestion of gas and a circulating liquid flow from the bottom of the vessel through the draft tube to the rotor.

Note: The flotation process in the IGF separator can be enhanced by the addition of polyelectrolyte chemicals to the produced water passing to the vessel.

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The ingested gas, in the form of small bubbles, assists the upward velocity of the oil droplets to float to the surface as a foam, where they are periodically skimmed off via an internal trough and removed under level control to the production sump. The flotation unit operates at 0.3 to 0.35barg, with any hydrocarbon gases breaking out of the produced water being discharged through a vent line to the first-stage VRU suction scrubber.

The produced water then leaves the first compartment via an external nozzle and flows into the second compartment under level control, where the flotation process is repeated but at the lower pressure of 0.05 to 0.1barg.

Produced water flows into the third compartment, or discharge cell, where any remaining oil/gas rises to the surface to be skimmed and collected in a boot, which discharges under level control to the production sump. Clean produced water exits the bottom of the induced gas flotation vessel into the overboard header, under level control, to be dumped overboard. The required overboard oil-in-water quality is 15ppm on a monthly average and 29ppm for a single occurrence.

Pressure Relief Valves 43-RV-348 and 43-RV-349 provide overpressure protection for Compartment 1 and Compartments 2 and 3 respectively. These RVs are set to relieve to the first-stage VRU suction scrubber at 0.5barg.

3.0 CONTROL AND INSTRUMENTATION

3.1 Produced Water Tank V-4340

Produced water discharged from the LP separators and bulk oil treater is combined in a manifold together with any clean water recycled from the produced water hydrocyclone and routed to the produced water tank to be degassed.

3.1.1 Level Control and Protection

The liquid level in the produced water tank is maintained at mid height of the vessel to give sufficient hold-up time for any dissolved gases to flash off.

The level is maintained at 2743mm above the bottom of the vessel by Level Indicating Controller 43-LIC-301 acting on 43-LCV-301A, located downstream of the produced water hydrocyclone to maintain back-pressure on the hydrocyclone.

There are High and Low Level Alarms, LAH-301 and LAL-301, derived from 43-LIC-301. The LAH and LAL annunciate in the CCR via the DCS and alert the operator to deviations from the set level control point allowing sufficient time to rectify the problem.

However, should the level in the produced water tank continue to rise or fall, independent High Level Trip LZH-302B or Low Level Trip LZL-302A operates and initiate executive action via the SSDS System. Refer to the latest revision of Cause and Effect Charts for full details on the executive actions resulting from these trips.

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3.1.2 Pressure Control and Protection

The released gas from the produced water tank is fed directly to the 1st stage VRU suction scrubber. The produced water tank is normally controlled by the VRU 1st stage suction pressure control system when VRU is running and by the atmospheric vent pressure controller system when the VRU is not running.

Pressure Controller 32-PIC-001, which is set at 0.05barg, controls the blanket gas make-up line. It is provided to prevent a vacuum being drawn on the produced water tank if insufficient gas is being liberated from the produced water entering the tank. It is also a means of preventing the ingress of oxygen during normal operations. Failure of 32-PIC-001 causes a USD shutdown by the activation of Low Low Pressure Trip 32-PZL-002. Instrument Tag Number Low Low Trip Low Alarm High Alarm High High Trip Controller Set Point 43-LZL-302A -27.4% 43-LIC-301 3.8% 66.7% 50% 43-LZH-302B 97.6% 32-PZL-002 0.017barg

32-PIC-001 0.03barg 0.3barg 0.052barg

Table 2.1 – Produced Water Tank Controllers, Alarms and Trips

3.2 Produced Water Pumps P-4340A/B

Produced water from Produced Water Tank V-4340 flows to the two produced water pumps, which share the same suction and discharge manifolds. Both pumps are rated for 100% duty.

3.2.1 Pump Control

The pumps are normally started and stopped from the DCS. The pumps can also be started and stopped from the starter in the MCC. An emergency stop pushbutton is located adjacent to each pump.

The produced water pumps can be set to operate in duty/standby configuration. The standby pump is automatically started after a time delay of 10 seconds for motor acceleration in the following circumstances:

• The duty pump trips

• The pump selected as duty fails to start

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Produced Water Pump P-4340A or B is protected against operation below its minimum flowrate by Flow Indicator Controller 43-FIC-321, which is set at 662m3_/hr,

minimum flow for a single pump. When the flow falls below this set point, Recycle Valve 43-FCV-321 opens to divert some flow from the discharge of the pump to flow back to the produced water tank, maintaining flow through the pump.

Pressure Controller 43-PIC-336 on the hydrocyclone clean water outlet provides an alternative control signal to the minimum flow controller for the produced water pumps. If the pressure at the clean water outlet of the hydrocyclone, as measured by 43-PIT-336, increases above 8barg, 43-PIC-336 overrides the signal from 43-FIC-321 opening 43-FCV-321 to reduce excessive back-pressure on the clean water outlet of the hydrocyclone and ensure effective operation of the hydrocyclone.

3.2.2 Pump Protection

Activation of the high high or low low discharge pressure trip shuts down the respective produced water pump via the SSDS System. Refer to the latest revision of Cause and Effect Charts for full details on the executive actions resulting from these trips.

Pump running indication is annunciated at the DCS via 43-XI-311 and 43-XI-312.

Instrument Tag Number Low Low Trip Low Alarm High Alarm High High Trip Controller Set Point 43-PZL-317 7barg 43-PZH-317 17.1barg 43-PZL-318 7barg 43-PZH-318 17.1barg

Table 2.2 – Produced Water Pumps Controllers, Alarms and Trips

3.3 Produced Water Hydrocyclone S-4340

Produced water from Produced Water Pumps P-4340A/B is directed into the produced water hydrocyclone, where the oily produced water is separated into a clean water stream, which exits to the induced gas flotation vessel and a reject oily water stream to the production sump.

3.3.1 Hydrocyclone Operation and Control

The two controlled variables, which affect operation of the produced water hydrocyclone, are the flowrate of produced water through the hydrocyclone and the reject ratio (ie the ratio of oil flow rejected to the inlet produced water flowrate).

To operate effectively, the hydrocyclone must operate over a given flow range (2.0m3_{/hr to 8.5m}3_{/hr per liner). Below the minimum flowrate, insufficient vortex is}

produced to effect efficient oil/water separation. Above the maximum flowrate, high swirl areas in the liner may result in erosion.

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The rate of flow is controlled by the action of produced water tank Level Indicating Controller 43-LIC-301, acting on Level Control Valve 43-LCV-301A on the clean water outlet line, in conjunction with flow and/or pressure control via 43-FIC-321 and 43-PIC-366 acting on the recycle valve 43-FCV-321. These control loops respond to changes in the level, flow and pressure in such a way as to achieve a balance between tight level control and stable flow conditions to the hydrocyclone.

The produced water tank Level Control Valve 43-LCV-301A, located downstream of the produced water hydrocyclone creates a back-pressure on the hydrocyclone. The oil contained in the core of the hydrocyclone is in a low pressure zone and the effect of the external back-pressure causes the oil to reverse its direction and flow back through the reject orifice, to the reject header and on to the production sump. The reject ratio is defined as the ratio of the reject oil stream flowrate to the inlet volume flowrate of fluid:

Reject Ratio % = Flow Inlet Total Flow Oil Reject x 100

Although the reject stream is designated ‘oil’, it typically contains less than 10% oil. For efficient operation, the reject ratio will typically be set at 2.5%.

A minimum reject ratio exists below which the efficiency of the hydrocyclones is severely reduced, the central core becomes unstable resulting in poor separation of oil and water. Extremely high reject ratios also have a similar effect.

The reject ratio can be determined without direct measurement by using the operating pressures across the hydrocyclone. The reject ratio is directly proportional to the Pressure Differential Ratio (PDR), which is defined as:

PDR = Pout Pin ej Pr Pin − −

Where: Pin = Inlet pressure (barg)

Pout = Water outlet pressure (barg) Prej = Reject pressure (barg)

As the flow through the produced water hydrocyclone varies in response to 43-LIC-301 so the produced water pressure differential, 43-PDIT-325A varies accordingly.

The differential pressure signals generated in 43-PDIT-325A, between oily water inlet and clean water outlet, and 43-PDIT-325B, across oily water inlet and oil reject, are fed to Differential Pressure Ratio Controller 43-PDRC-325, which is located in the produced water hydrocyclone UCP and set at 1.5.

This instrument controls the oil reject flow by modulating Pressure Difference Control Valve 43-PDCV-325 on the reject line to react in order to maintain a constant PDR of 1.5, and hence constant reject ratio.

High and low PDR alarms are provided. The High PDR Alarm 43-PDAH-325, set at 1.6, warns of unnecessarily excessive reject stream flowrates, ie there may be too few hydrocyclone liners installed. A Low PDR Alarm 43-PDAL-325, set at 1.4, warns of impaired separation performance, ie there may be too many liners installed and the number should be reduced by removing liners and installing blanks.

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Provided the differential pressure ratio is maintained across the produced water hydrocyclone, the performance is unaffected by alterations in the flowrate of produced water directed to the hydrocyclone, if the flow is within the minimum/maximum flowrate for the liners.

There are no trip conditions for Produced Water Hydrocyclone S-4340.

3.4 Induced Gas Flotation Separator S-4341

Produced water from the hydrocyclone flows to the Petrico induced gas flotation separator for further treatment and reduction of oil-in-water content.

The IGF separator is a horizontal, multi-cell, depurator vessel, which removes the entrained oil particles from the produced water by floating them to the surface using fine gas bubbles. Floating oil is skimmed from the surface of the produced water and the fully treated water is discharged overboard at 15ppm.

3.4.1 Produced Water Level Control and Protection

Clean produced water from the hydrocyclone flows under level control of 43-LIC-301 to the IGF separator, as described in Paragraph 3.3.1, and enters the first compartment through an underflow baffle.

The two cells in Compartments 1 and 2 operate together. The produced water leaves the first compartment and enters the second compartment through a second baffle and then passes on to a third, single-cell compartment.

Note: All descriptions in the following paragraphs refer to Compartment 1. The equivalent tag numbers for Compartment 2 are indicated in parenthesis alongside Compartment 1 tag numbers.

The produced water level in the compartment is maintained at a constant level by Level Indicating Controller 43-LIC-502 (512) modulating 43-LCV-502 (512) on the produced water line to the next compartment. High and low level alarms 43-LAH-502 (512) and 43-LAL-502 (512) annunciate in the CCR via the DCS and alert the operator to deviations from the set level control point.

The compartment is fitted with a magnetic type Level Gauge 43-LG-504 (514) and Level Transmitter 43-LZT-504 (514), which provides high high and low low trip signals to the SSDS System.

Produced water from the second compartment flows into the third compartment or discharge chamber, where any remaining oil rises to the surface and is skimmed via the boot to the production sump.

The produced water level in the third compartment is monitored by two level transmitters. Level Transmitter 43-LIT-522 provides the process variable signal to 43-LIC-522, which modulates Level Control Valve 43-LCV-522 on the clean water outlet line and provides high and low level alarms. Level Transmitter 43-LZIT-524 provides high and low trip signals to the SSDS System.

These trip conditions are also repeated via the DCS. Refer to the latest revision of Cause and Effect Charts for full details on the executive actions resulting from these trips.

Clean produced water exits the bottom of the third compartment under the level control of 43-LCV-522 to the overboard header and is directed through the overboard caisson to the sea.

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3.4.2 Skimming Control and Protection

The system provides an auto-skimming function for Cells 1 and 2. (Cell skimming for the cells is independent of each other.) Oily froth is skimmed from the surface of the produced water into the skimmings boot by raising the level up to 2641mm (configurable) via the DCS facilities at timed intervals (typically 15 to 30 seconds every 30 minutes) using control loops 43-LIC-502 (512) modulating 43-LCV-502 (512). Normally oil is skimmed off on an intermittent basis as the produced water level builds up. There is no requirement to inhibit the high level alarms and trips during skimming. The operator has the facility to disable auto-skimming.

Note: All descriptions in the following paragraphs refer to Compartment 1. The equivalent tag numbers for Compartment 2 are indicated in parenthesis alongside Compartment 1 tag numbers.

The skimmings level in the boot is continuously monitored by two level transmitters. Level Transmitter 43-LIT-501 (511) provides the process variable signal to 43-LIC-501 (511), which modulates Level Control Valve 43-LCV-501 (511) on the skimming outlet line to the Production Sump. Transmitter 43-LZIT-503 (513) provides high and low trip signals to the SSDS System.

Two level transmitters continuously monitor the liquid level in the skimmings boot provided for the third compartment. Level Transmitter 43-LIT-521 provides a signal for level control via 43-LIC-521, which modulates 43-LCV-521 on the skimmings outlet line and provides a high and low level alarm. Transmitter 43-LIT-524 provides high high and low low level trip signals to the SSDS System.

These trip conditions are also repeated via the DCS. Refer to the latest revision of Cause and Effect Charts for full details on the executive actions resulting from these trips.

3.4.3 Pressure Control

A 2in blanket gas supply line is hard piped from the Blanket Gas System to the inlet nozzles, which distribute the gas to the IGF separator compartments.

The operating pressure in Compartment 1 is maintained at 0.3barg by blanket gas entering the IGF separator through self-regulating 44-PV-381 on the blanket gas supply line. The flowrate of blanket gas passing to Compartment 1 is measured by Flow Transmitter 44-FIT-382 and displayed on the DCS via 44-FI-382. If the pressure in the compartment increases up to 0.35barg, excess gas is directed to the first-stage VRU suction scrubber through self-regulating 44-PV-344 on the vent line. Compartments 2 and 3 are maintained at the lower pressure of 0.05barg by blanket gas entering the IGF separator through self-regulating 44-PV-383 on the blanket gas supply line and leaving the cells through 44-PV-383, which is set at 0.1barg. The released gas is fed directly to the vent for safe disposal.

The flowrate of blanket gas passing to Compartments 2 and 3 is measured by Flow Transmitter 44-FIT-384 and displayed on the DCS via 44-FI-384.

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3.5 Overboard Discharge Water Quality

The quality of the water leaving the clean water compartment is monitored by an oil-in-water analyser 43-AZE-355. The analyser provides a high oil content trip signal to the SDSS logic if the oil content of the discharge water approaches 15ppm. The control logic opens the Shutdown Valve 43-SDV-351 to direct the out-of-spec water to the slop oil tank or primary reception tank and then closes the 43-SDV-381 to the overboard header. When the water quality is restored the operator can rest the trip to direct water overboard.

Instrument Tag Number Low Low Trip Low Alarm High Alarm High High Trip Controller Set Point Compartment 1 43-LZL-504 5.1% 43-LIC-502 22.2% 73.8% 28% 43-LZH-504 86.9% 43-LZL-503 20% 43-LIC-501 37.5% 62.5% 45% 43-LZH-503 75% Compartment 2 43-LZL-514 5.1% 43-LIC-512 22.2% 73.8% 28% 43-LZH-514 86.9% 43-LZL-513 25% 43-LIC-511 37.5% 62.5% 45% 43-LZH-513 75% Compartment 3 43-LZL-524 40.7% 43-LIC-522 49.4% 66.8% 56% 43-LZH-524 75.5% 43-LIC-521 37.5% 62.5% 45% 43-LZH-523 75% Clean Water Discharge

43-AZH-355 25ppm 30ppm

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4.0 MODES OF OPERATION

Oily water from LP separators and bulk oil treater passes into Produced Water Tank V-4340 under interface level control.

The flow of produced water from the tank is controlled via the DCS Level Controller 43-LIC-301, which modulates Level Control Valve 43-LCV-301A on the clean water outlet downstream of the hydrocyclone to maintain the required level in the produced water tank. Any free oil accumulating on the surface of the produced water in the tank is manually skimmed to the collection sump.

Produced water from the tank is directed to Produced Water Pumps P-4340A/B as there is insufficient pressure in the tank to drive it through the hydrocyclone. The produced water pumps are operated from the DCS on a continuous basis. The pump selected for standby will automatically start in the event of duty pump failure.

Produced Water Hydrocyclone S-4340 operates without intervention provided that the hydrocyclone is maintained within the minimum/maximum flowrates for the total number of liners installed. As the flow of produced water increases, more liners can be brought online as required. The addition of extra liners within the hydrocyclone requires the unit to be taken out of service, isolated and the work carried out under Permit to Work conditions by the vendor.

The hydrocyclone is back-flushed by closing the oil reject line and opening the back-flush valve for 30 seconds (configurable) to ensure the reject flow orifice remains clear and correct separation efficiency is achieved. The back-flush sequence can be manually initiated or set to automatically initiate at a certain time. Induced gas flotation separator is operated remotely from the DCS to degas and polish the produced water from the hydrocyclone. Normally, oil is skimmed off intermittently as the level of oil at the interface builds up. The duration of skimming and the cycle time are field adjustable.

Regular samples must be taken from the produced water outlet of the IGF separator to ensure that the oil content of the produced water directed to the overboard caisson is within specification.

The produced water to the overboard caisson is also monitored by Oil-in-water Analyser 43-AZE-355, which generates a High Oil Content Alarm on the DCS.

5.0 SAFEGUARDING

Produced Water Tank V-4340 is protected against vacuum conditions by the Pressure/Vacuum Relief Valve 43-RV-303. This vacuum breaker is set to operate at 26mbarg (vacuum) and is located in an accessible area.

A Pressure Transmitter 32-PZIT-002 located on the gas outlet line provides a low low trip signal to the ESR and SSDS System. Activation of 32-PZL-002 initiates a shutdown of the Produced Water System (System 43 Shutdown).

The instrument bridles for the produced water tank are fitted with an independent Level Switches 43-LZT-302A and B. These instruments provide trip signals to the ESR and SSDS System.

The primary means of safeguarding Produced Water Pumps P-4340A/B is provided on the ESR and SSDS System via suction valve position indication, system inhibits on pump starts.

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Protection for Produced Water Pumps P-4340A/B is provided by Pressure Transmitters 43-PZIT-317/318 located on the pump discharge lines. The ESR and SSDS System receives signals from the pressure transmitter to trip the pump on low low or high high discharge pressure.

Produced Water Hydrocyclone S-4340 does not have any trip functions of any description. Thermal protection for the produced water hydrocyclone is provided by 43-RV-323, on the produced water inlet line which is set to operate at 24.1barg. Liquid supply overpressure protection from the produced water pumps to the IGF separator is provided by 43-RV-347A and B, which are set to operate at 1.03barg. Induced Gas Flotation Separator V-4341 is fitted with a series of level transmitters, which monitor the operating levels in the vessels.

The oil/water separation cells are fitted with magnetic type level transmitters, which provide a high high and low low trip signal to the ESR and SSDS System. All skimming compartments are fitted with independent level transmitters. These instruments provide level control and trip signals to the ESR and SSDS System.

Gas overpressure protection for the IGF separator is provided by Pressure Relief Valves 43-RV-348 and 43-RV-349 set to relieve at 1.0barg.

Equipment Sizing Basis RV Tag No Setting

Produced Water Tank V-4340 Vacuum Basis 43-RV-303 -26mbar Produced Water Hydrocyclone

S-4340

Thermal 43-RV-323 24.1barg

Produced Water to IGF Separator V-4341

Blocked Flow 43-RV-347A/B

1.03barg

IGF Separator V-4341 Gas Flow from fully open Blanket Gas Valve

43-RV-348

43-RV-349 0.5barg 0.5barg

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OPRM-2003-0311 _{Page 16 of 18} 30-April-2006

FFigure 2.1 – Produced Water Tank and PPumping Facilities

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FFigure 2.2 – Produced Water Hyydrocyclone

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FFigure 2.3 – Induced Gas FFlotation Separator

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PART 2 OPERATING PROCEDURES

Section 1 System Operating Procedures

Section 2 Equipment Operating Procedures

Section 3 Supplementary Operating Procedures

Part 2 Operating Procedures

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Part 2 Operating Procedures

Section 1 System Operating Procedures

Procedure Number

PRODUCED WATER TREATMENT SYSTEMS OPERATING PROCEDURES

PROCEDURE NO 1/001: COLD START-UP PROCEDURE NO 1/002: HOT START-UP PROCEDURE NO 1/003: NORMAL OPERATION PROCEDURE NO 1/004: PLANNED SHUTDOWN

PROCEDURE NO 1/005: PROCESS AND EMERGENCY SHUTDOWN

Part 2 Section 1 System Operating Procedures

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SYSTEM/EQUIPMENT: PRODUCED WATER TREATMENT SYSTEMS

PROCEDURE NO 1/001: COLD START-UP

THE WHOLE OF THIS PROCEDURE MUST BE READ THROUGH AND FULLY UNDERSTOOD BEFORE CARRYING OUT ANY OF THE

FOLLOWING ACTIONS.

INTRODUCTION

This procedure details the operator actions required to be carried out on the Produced Water Treatment System for a cold start-up, typically following major maintenance activities.

If the system or parts of the system have been open for maintenance work or for any other reason, the vessels or pipework may contain air/oxygen. Under these circumstances, the affected facilities must be nitrogen purged prior to the introduction of produced water. Due to the likelihood that the water cuts on the producing wells will increase at a later stage in the field life, it may be necessary to consider starting the produced water treatment system and run on recycle prior to opening the producing wells to prevent the possibility of high water trips on the separation system.

PRECONDITIONS

Supporting Drawings

The cold start-up procedure utilises the following P&IDs: • BON-AME-3PP-B-21443-001-C06

• BON-AME-3PP-B-21443-002-C06 • BON-AME-3PP-B-21443-003-C06 • BON-AME-3GN-B-21448-001-C06

Interface Systems

Before the Produced Water Treatment System can be started, the following systems are required to be operational:

• Oil Separation and Treatment. Refer to POPM Volume 3 (OPRM-2003-0303) • Flare and Vent Systems. Refer to POPM Volume 10 (OPRM-2003-0310) • Chemical Injection and Methanol Injection System. Refer to POPM Volume 13

(OPRM-2003-0313)

• Fuel Gas System. Refer to POPM Volume 14 (OPRM-2003-0314) • Drainage Systems. Refer to POPM Volume 16 (OPRM-2003-0316)

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• Instrument Air and Utility System. Refer to POPM Volume 25 (OPRM-2003-0325) • Power Generation and Distribution Systems. Refer to POPM Volume 30

(OPRM-2003-0330)

Pre-requisites

• No Permits to Work are in force that may prohibit start-up of the Produced Water System • After completion of all maintenance activities, all workscope documentation must be

completed and signed-off by the relevant authorities before the start-up can commence • All spades and spectacle blinds are in their correct positions as per the Produced Water

System P&IDs listed in Supporting Drawings

• All disturbed flanges and fittings in the system have been nitrogen leak/pressure tested as appropriate, and any leak test certificate signed-off. The produced water facilities have been purged with nitrogen and left with a slight positive nitrogen pressure

• All system pipework drain, vent, purge and sample point valves are closed • All system equipment drain and vent valves are closed

• All instrument isolation valves are open

• All level bridle process isolation valves are open and vent and drain valves are closed • The isolation valves for Oil-in-water Analyser 43-AZE-355 are closed

• The DCS, SSDS and ESS control and shutdown facilities are operational and healthy • Toolbox talks have been held with all directly and indirectly concerned parties outlining

the workscope and procedure

• Communications are established between all personnel involved in this procedure • All level bridle process connection valves are open

PLANT STATUS

• The system isolation valves are positioned as indicated in Valve Checklist No 1 Pre-start Positions – Produced Water System Cold Start-up

• Oil-in-water Analyser 43-AZE-355 has been calibrated and is available for use

• The production sump is prepared to accept reject oil from the produced water hydrocyclone and IGF separator

• The slop oil or primary reception tank are prepared to accept off-spec treated produced water from the induced gas flotation separator

• The overboard header and caisson are prepared to accept on-spec treated produced water from the induced gas flotation separator

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VALVE CHECKLIST NO 1: PRE-START POSITIONS: PRODUCED WATER SYSTEM COLD START-UP

Tag No Function Setting Checked

LP Separator V-2341A

Refer to P&ID BON-AME-3PP-B-21423-002-C06

23-SDV-045 12in produced water outlet SDV from V-2341A CLOSED 23-BLV-079 12in produced water outlet ball valve from

V-2341A upstream of 23-LCV-032 OPEN 23-BLV-082 12in produced water outlet ball valve from

V-2341A downstream of 23-LCV-032 OPEN 23-SDV-046 12in produced water outlet SDV from V-2341A

to the produced water tank CLOSED

LP Separator V-2341B

23-SDV-075 12in produced water outlet SDV from V-2341B CLOSED 23-BLV-122 12in produced water outlet ball valve from

V-2341B upstream of 23-LCV-062 OPEN 23-BLV-125 12in produced water outlet ball valve from

V-2341B downstream of 23-LCV-062 OPEN 23-SDV-076 12in produced water outlet SDV from V-2341B

to the produced water tank CLOSED

Bulk Oil Treater V-2243

Refer to P&ID BON-AME-3SP-B-21423-007-C06

23-SDV-143 12in SDV at outlet from V-2343 CLOSED 23-BLV-220 8in ball valve at inlet to 23-LCV-134 OPEN 23-BLV-223 8in ball valve at outlet from 23-LCV-134 OPEN 23-BLV-224 6in ball valve at 23-LCV-134 bypass CLOSED

Produced Water Tank and Pumps

44-BLV-280 Isolation Block Valve for Fuel Gas Supply to

Tank upstream of 32-PCV-001 LOCKED OPEN 44-BLV-281 Isolation Block Valve for Fuel Gas Supply to

Tank downstream of 32-PCV-001 LOCKED OPEN 43-BLV-233 Isolation Valve on Skim at Nozzle N6A CLOSED 43-BLV-238 Isolation Valve on Skim at Nozzle N6B CLOSED 43-BLV-234 Isolation Valve on Skim at Nozzle N6C CLOSED 43-BLV-239 Isolation Valve on Skim at Nozzle N6D CLOSED 43-BLV-235 Isolation Valve on Skim at Nozzle N6E CLOSED 43-BLV-240 Isolation Valve on Skim at Nozzle N6F CLOSED 43-BLV-236 Isolation Valve on Skim at Nozzle N6G CLOSED