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REVISION CHANGE NOTICES Revision A1 A2

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Location of Changes First Issue Section 3.2 Section 3.2 Section 3.4 Section 3.4.1 Section 3.4.2 Section 3.5.3 Section 3.6.3 Section 4.3 Section 4.3.3.4 Section 4.5.2 Section 4.6.1 Section 4.6.2 Section 4.6.3 Section 4.10 Section 3.2 Section 3.4.4/ 3.5.1 Section 4.10.1 Section 4.4 / 4.4.1 / 4.5.3 Section 4.6.1 Section 5 Relevant pages

HOLDS TABLE Location Hold

Brief Description of Change Issued for IFR Delete EC PW Pumps Revise operating temperature and produced water scheme description. Revise produced water system description. Revise produced water hydrocylone description. Revise flotation unit description. Revise pressure at riser. Revise water injection pressure. Revise Fuel Gas Cooler tag number. Revise differential set point temperature. Add Seawater Heater description. Revise Flare KOD description. Revise Flare Condensate Return Pump description. Add propane cylinder information. Revise chemical injection system. EC rundown stream water content specification PW transfer pump tag Oxygen scavenger tank blanketing requirement Dump caisson is deleted. Flare KO Drum sizing basis Section 5 – Inherently Safe Design deleted Changes denoted by right border

Action

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TABLE OF CONTENTS 1.

INTRODUCTION ......................................................................................................................... 6 1.1 1.2 1.3 1.4

2.

OVERVIEW ................................................................................................................................. 8 2.1 2.2

3.

GENERAL .................................................................................................................... 8 DESIGN CAPACITIES AND SPECIFICATIONS ....................................................... 10

PROCESS FACILITIES............................................................................................................. 11 3.1 3.2 3.3 3.4

3.5 3.6 3.7 3.8 4.

BACKGROUND ........................................................................................................... 6 PROJECT OBJECTIVES ............................................................................................. 6 DOCUMENT SCOPE ................................................................................................... 6 ABBREVIATIONS ........................................................................................................ 7

SUB SEA PRODUCTION FACILITIES ...................................................................... 11 WELL FLUID SEPARATION SYSTEM ..................................................................... 11 TEST SEPARATOR ................................................................................................... 13 PRODUCED WATER TREATMENT SYSTEM.......................................................... 17 3.4.1 FWKO Drum Hydrocyclones (30-VJ-1610A/B & 30-VJ-1620A/B) ................. 17 3.4.2 LP Separator Hydrocyclones (30-VJ-1613/1623) .......................................... 17 3.4.3 1st & 2nd Stage Flotation Units (30-VV-1611/1612/1621/1622 A/B) and Flotation Recycle Pumps (30-PC-1612/1622 A/B/C) ................................................. 17 3.4.4 PW Degasser (30-VG-1615/1625) & PW Degasser Oil Pumps (30-PC1611/1621A/B) ............................................................................................................ 17 3.4.5 Off-Spec Produced Water ............................................................................ 17 3.4.6 PW Transfer Pumps ..................................................................................... 17 WI/HSP FINE FILTRATION PACKAGE (35-AY-6310) ............................................. 17 SAND CLEANING PACKAGE (20-AY-6330)............................................................ 18 HSP POWER FLUID SYSTEM .................................................................................. 19 WATER INJECTION SYSTEM .................................................................................. 20

UTILITY SYSTEM ..................................................................................................................... 21 4.1

4.2 4.3

4.4

4.5

INSTRUMENT AIR AND UTILITY AIR SYSTEM ...................................................... 21 4.1.1 Instrument Air Process Description ................................................................ 21 4.1.2 Utility Air System ............................................................................................ 21 NITROGEN SYSTEM ................................................................................................. 21 FUEL GAS SYSTEM .................................................................................................. 22 4.3.1 LP Gas Cooler / KO Drum and Fuel Gas Compressors / Cooler ............. 22 4.3.2 Fuel Gas Import Facilities ............................................................................ 23 4.3.3 Fuel Gas Conditioning ................................................................................. 23 SEAWATER TREATMENT SYSTEM ........................................................................ 25 4.4.1 GENERAL ...................................................................................................... 25 4.4.2 Seawater Treatment System ....................................................................... 26 SEAWATER FILTRATION AND DISTRIBUTION ..................................................... 26 4.5.1 Seawater Coarse Filtration .......................................................................... 26 4.5.2 Seawater Distribution for Cooling Duty ..................................................... 26 4.5.3 Seawater Heater ............................................................................................ 27 4.5.4 Seawater Fine Filtration ............................................................................... 27 4.5.5 Sulphate Reduction System ........................................................................ 27

4.6

4.7 4.8 4.9 4.10 4.11

4.12

5.

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4.5.6 Deaeration System ....................................................................................... 27 4.5.7 Chemical Transfer Skid................................................................................ 28 FLARE SYSTEM ........................................................................................................ 28 4.6.1 Flare Knock Out Drum .................................................................................... 28 4.6.2 Flare Condensate Return Pumps ................................................................... 29 4.6.3 Flare Tip and Ignition panel ............................................................................ 29 CLOSED DRAIN SYSTEM ........................................................................................ 29 OPEN DRAIN SYSTEM ............................................................................................. 30 DIESEL SYSTEM ....................................................................................................... 30 CHEMICAL INJECTION SYSTEM ............................................................................ 30 4.10.1 Process Chemical Injection Storage Tanks and Pump Package ................. 30 STEAM SYSTEM ....................................................................................................... 34 4.11.1 General ......................................................................................................... 34 4.11.2 Steam generation system ............................................................................. 34 4.11.3 Waste Heat Recovery Units ......................................................................... 35 4.11.4 Fuel for Steam Boilers .................................................................................. 36 OTHER UTILITY SYSTEMS ...................................................................................... 36 4.12.1 Fresh Water .................................................................................................. 36 4.12.2 Fuel Oil ......................................................................................................... 36 4.12.3 Inert Gas ....................................................................................................... 36 4.12.4 Power Generation......................................................................................... 37 4.12.5 Diesel Biocide Injection System ................................................................... 37 4.12.6 Hydraulic Oil Transfer System ...................................................................... 37

REFERENCES .......................................................................................................................... 39

1. 1.1

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INTRODUCTION BACKGROUND The Kraken Field is located in UKCS block 9/02b, approximately 400 km north east of Aberdeen in a nominal water depth of 116m. The Kraken field development consists of the provision of subsea and FPSO production facilities to deliver stabilised oil to a shuttle tanker from 14 production wells. The Kraken field development consists of the provision of subsea and FPSO production facilities to deliver stabilized oil to a shuttle tanker from 25 wells (14 producers and 11 water injectors). The Kraken product is heavy oil with a gravity of approximately 13.7° API. The development of Kraken requires multiple drilling/production centres which will be subsea developments tied back to the FPSO. The FPSO is designed as a harsh environment production facility. HSPs in each production well supplied with power water from the FPSO are provided lifting the viscous crude from the low pressure reservoir. Water injection facilities are provided for reservoir pressure support, voidage replacement and to sweep the oil to the producers. As a result of the low GOR, associated gas and crude will be used for power generation, with the possibility of import gas in later life. Gas import via a dedicated import pipeline tied into an existing 3rd Party trunk line is a future possibility and therefore included. The heavy oil forms a strong viscous emulsion with water; however, this will be managed with the hydraulic submersible pump (HSP) power water, which mixes with the crude oil at the well head producing more favourable separation of oil and water phases. BAB will base the FPSO on the existing tanker PRISCO ALCOR (the Tanker), which shall undergo an extensive conversion programme for conversion to the FPSO role. The FPSO shall sail under its own power from conversion yard in Singapore to a port in Northern Europe (Rotterdam) and then will be towed from the port to the field for hook-up and installation.

1.2

PROJECT OBJECTIVES The overall project objective is to exploit the reserves in the Kraken field in a timely and cost effective manner that maximises the recovery, and meets EnQuest’s HSSE policy, value, strategy, operability, technical and deliverability targets.

1.3

DOCUMENT SCOPE The purpose of this document is to provide the description of the process facilities and utility systems on the Kraken FPSO Topsides.

1.4

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ABBREVIATIONS The following terms are generic to the Kraken Field Development Project and may be referred to in this document: List of Abbreviations Abbreviation

Definition

AC API BAB BFW

Alternating Current American Petroleum Institute Bumi Armada Berhad Boiler Feed Water

BOPD BS&W BWPD CFU EC FG

Barrels of Oil Per day Base Sediment and Water Barrels of Water Per Day Compact Flotation Unit Electrostatic Coalescer Fuel Gas

FPSO FWKO GOR HP

Floating Production Storage & Offloading Free Water Knock Out Gas Oil Ratio High Pressure

HSP

Hydraulic Submersible Pump

ISO LAT LP

International Standards Organization Lowest Astronomical Tide Low Pressure

MBD MMscfd MWe ppb ppmv

Thousand Barrels per Day Million standard cubic feet per day Mega Watts electrical Parts per billion parts per million by volume

pptb PW RVP

pounds per thousand barrels Produced Water Reid Vapour Pressure

SRP TDS TVP UKCS

Sulphate Reduction Package Total Dissolved Solids True Vapour Pressure UK Continental Shelf

WI

Water Injection

2.

OVERVIEW

2.1

GENERAL

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The main facilities on the FPSO are: •

Well Fluid Collection facilities, HSP Power water and WI distribution facilities located on Turret of the FPSO

•

Well Fluid Separation facilities

•

Storage of the Stabilized Oil Produced

•

Utilities required for Process the Fluids and Operating the FPSO

•

Facilities for treating the produced water to meet water Injection and HSP Power Water Specifications

•

Facilities for transferring the Oil from the FPSO to the Shuttle tankers

This document should be read in conjunction with PFDs [Ref.: 3] and UFDs [Ref.: 4] Hydraulic submersible pumps (HSPs) located in the reservoir are driven by high pressure water (HSP power water), for artificially lifting the well fluids from the low pressure reservoir of Kraken field. The produced water separated from the fluids is treated on the FPSO and pumped by HSP Power water Pumps and supplied back to the HSP pump drive. The HSP power water from the outlet of HSP turbine drive combines with the reservoir fluids and is pumped back along with the well fluids to the FPSO by the HSP pumps. The well fluid is collected from three clusters of wells and from each clusters the well fluids are routed to the FPSO through two subsea flow lines. The well fluids are received on the FPSO through six production pipeline risers. There are two trains of well fluid separation having FWKO, LP separator and Electrostatic Coalescer. The oil separated from the separation facilities is stored in the storage Tanks located in the hull of the FPSO. The produced water is treated to remove solids and oil to meet specifications of HSP power water and WI water. The separated gas from FWKO vessel is routed to the Fuel gas conditioning unit. LP gas from the LP separator is cooled by sea water in a Shell and tube exchanger and sent to LP Gas KO Drum to separate the liquids condensed. The separated gas from LP Gas KO Drum is compressed in the compression system before it is combined with the gas from the FWKO Vessel.

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Sea Water is filtered, treated to reduce sulphates and then de-aerated to remove dissolved oxygen for supplementing the produced water for Water Injection and HSP Power water as required. Steam is used for process heating on topsides, as the motive force for the cargo offloading pumps in the hull. The hull cargo storage tanks also use steam to maintain produced crude at the correct temperature. Steam is generated from 3 x 50% steam boilers, which can be fired on crude oil, fuel gas or diesel. The steam from these boilers will be generated at 16 barg. Additional steam generation comes from the Waste Heat Recovery Unit on the Power Generators, which produce steam at 5.2 barg. The 16 barg steam is supplied to the hull to drive the cargo pumps as well as other miscellaneous users. Steam at 10 barg (let down from 16 barg system) is used to heat the crude oil storage tanks in the hull. A pressure let down facility is provided to generate steam at 5.2 barg from the steam at 16 barg and one more let down level of steam from 5.2 barg to 1.5 barg. Steam at 5.2 barg and 1.5 barg is used to heat the process streams where necessary. The utility systems on the FPSO include: •

Diesel System

•

Instrument Air and Utility air systems

•

Nitrogen Generation system

•

Flare and Drain systems

•

Steam generation system

•

Power Generation system

•

Essential Power Generator

•

Inert Gas generation system

•

WHRUs

•

Fuel Gas compression, gas import and Fuel Gas conditioning system

•

Fresh water generation and distribution system

•

Electrochlorination system

•

Chemical Injection system

•

SW Treatment system

•

FW Distribution and Deluge system

•

Diesel Biocide Injection System

•

Hydraulic Oil Transfer System

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Design Life The design life of the Kraken Facilities is 25 years.

2.2

DESIGN CAPACITIES AND SPECIFICATIONS The Kraken topsides design capacities are as follows (Ref. 1, Section 7.5.1): Topsides Design Capacities Peak liquids production rate

460 MBD

Nameplate oil production

80 MBD

Nameplate gas handling

20 MMscfd

Nameplate water production

275 MBD

Nameplate HSP production

225 MBD

Nameplate water injection

275 MBD

Nameplate gas import

15 MMscfd

Nameplate oil offloading

4500 m /h

Nameplate treated seawater makeup

80 MBD

3

The product crude oil specification is as follows (Ref. 1, Section 7.6.1): Parameter

Specification

TVP

0.9 bara at 50 C (crude storage temp)

RVP

0.76 bara (11 psia)

BS&W

< 0.5 vol%

SALT

< 70 pptb

o

Dispersed oil-in-water (for overboard discharge), shall target ≤ 15 ppmv max and at all times it will be ≤ 30 ppmv as per current legislation (Ref. 1, Section 7.6.3)

3. 3.1

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PROCESS FACILITIES SUB SEA PRODUCTION FACILITIES The subsea production facilities consist of mainly:

3.2

•

Four Drill Centres of subsea Production Wells and WI wells (Drill centres 3 & 4 are daisy chain arrangement)

•

Six subsea production pipe lines and risers at the turret of FPSO

•

A test header connecting all wells for testing the well fluid flow rates.

•

Three HSP Risers, Power Water subsea pipe lines and facilities for distribution of Power Water to the HSP pumps

•

Three WI Risers and injection facilities

•

One gas import riser

•

Three Subsea umbilical control system

WELL FLUID SEPARATION SYSTEM Well fluids commingled with HSP power water arrive at the FPSO via production risers and are routed to the production manifolds and test manifold. The turret accommodates the swivel stack which allows the vessel to weathervane freely. On the FPSO topsides, Well fluids are processed in two parallel oil processing trains A and B, each sized for 50% of design capacity. Each of the two trains has a capacity to process well fluid to yield 40 MBD of stabilized crude oil to storage. Each oil train consists of the following equipment: Equipment Title

Train A

Train B

Free Water Knock Out (FWKO) Drum

30-VS-1110

30-VS-1120

Oil/Oil Exchanger

30-HP-1110

30-HP-1120

Oil/PW Exchanger

30-HP-1111

30-HP-1121

Oil Heater

30-HE-1112

30-HE-1122

LP Separator

30-VS-1210

30-VS-1220

Electrostatic Coalescer

30-VE-1211

30-VE-1221

LP Separator PW Pumps

30-PC1210A/B

30-PC1220A/B

Oil Transfer Pumps

30-PC-1212A/B

30-PC-1222A/B

Oil Cooler

30-HP-1213

30-HP-1223

Described below is the process for Train-A, Train-B is identical.

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The well fluids enter the FWKO Drum 30-VS-1110, which separates free water and gas from the well fluids. The FWKO operates at approximately 9.5 barg and 45°C. The oil flows over a weir into the oil compartment of the vessel and under level control exits to the Oil/Oil Exchanger 30-HP-1110. Due to the high viscosity and high gravity of the Kraken crude, the Oil leaving the FWKO Drum may contain up to 40% of emulsified water and considerable quantity of gas as carry under gas (20% of total gas liberated in FWKO Drum considered in design). The oil level in the FWKO Drum is controlled by a LCV located in the FWKO Drum oil outlet line. The produced water leaving FWKO Drum will contain around 1% of oil in water. The emulsified oil from the FWKO Drum is heated by exchanging heat with the crude oil from Electrostatic Coalescer in Oil/ Oil exchanger 30-HP-1110 to a temperature of about 68 °C and then it is heated by hot PW to a temperature of about 108 °C. The Oil stream is then heated to 140 °C by steam in the oil heater 30-HE-1112 before it enters the LP separator. The oil feeding the oil heater is a combined stream of oil from the FWKO Drum, reject oil stream from the PW treatment system, condensate from the LP Gas FWKO Drum and recovered oils from Slop and Off-spec tanks from Hull. The operating pressure of LP Separator 30-VS-1210 is maintained at 3.4 barg under back pressure control of the outlet gas. The LP separator 30-VS-1210 separates most of the emulsified water due to a decrease in viscosity at 140 °C and it is expected that the oil leaving the LP separator will contain