long distance subsea control - norwep · pdf filelong distance subsea control | 4 field- and...

Long Distance Subsea Control

Sigurd Moe

Cairo, 12. February .2017

Long Distance Subsea Control | 2

� Introduction

� Subsea control system architecture

� Power and communication

� Technology opportunities

Agenda


• Gas

• 50 - 300 km subsea to beach• 600 km studied and deemed feasible

• Flow assurance crucial

• Hydrate control • Multiphase (Wet gas) metering

• Continous hydrate inhibitor injection (MEG)

• System for remote control of injection per well

• Slug handling

• Large bore, lots of energy, enhanced monitoring being requested

• Sand detection

• Vibration monitoring

• Leakage detection

• Need for accurate positioning of chokes to balance wells• Electric choke valve resolution advantageous

• Gas Compression often considered in late life

Long distance field charcteristics

Shell Ormen Lange – 120 km Subsea to beach Norway

Subsea System by TechnipFMC, production start 2007

Laggan Tormore

Total Laggan Tormore – 187 km Subsea to beach UK. Subsea System

by TechnipFMC, production start 2016


Field- and region specific architecture

Cluster Solution Template Solution

Except distribution of power and signal, control system components are basically the same


Functionality - Subsea Control System

1. Safety - Automatically or manually shuts in the subsea system

in abnormal situations

2. Operator Interface during Daily Operation- Operation of subsea valves and chokes

- Monitoring of production parameters and system integrity

3. Provides Data for Reservoir Management- Monitors, stores and trends pressure and temperature

and other reservoir related parameters


Control System – Topside/Land

Injection

Chemicals

Hydraulic

Power unit

Master

ControlStation

Subsea Power &

CommunicationUnit

Topside

Gateway

Control

Umbilical

Umbilical

Hangoff


Subsea Equipment

Tree Mounted Controls - Instrumentation and Subsea Control Module

Power consumption:• 200 – 300 W per well

Communication, typical:• 1- 5 kbps per well for normal

operation• 1 Mbps + if seismic data or video

streaming


Umbilical and Distribution

Template distribution

Umbilical

Cluster distribution


Power and Communication Architecture

Communication

on power cable

Point to point

fiber optical

communication

Distribution using

Subsea Router Module

(SRM)


(SRM) with topside

functionality “Topside

repeated subsea”


Communication on power cable

Multidrop

communication

on power cable

• Normally lowest cost solution• Uses power lines for communication• No subsea router needed• No fiberoptics

• Shorter distances, up to 80 km typically• But 120 km field proven @ 1200 bps

• Typically two (redundant) cable pairs per 4

wells• 8 - 12 wells possible

• Up to 900 V in operation

• Communication speed• 1.5 Mbps up to 40 km• 100 kbps up to 80 km


Principle of operation – signal on power line


Signal transmission over the power lines will eliminate the need for dedicated signal cables;

• Increases reliability as component count (cable elements and connector pins) is divided by 2

• Reduces control umbilical cost with typically more than 5%

• Increases distance as power cables normally have larger cross section than signal cables

Why Signal on Power Line?

Umbilical with separate signal cable Umbilical for communication on power line


Point to point fiber optical communication

Point to point

fiber optical

communication

• Up to 200 - 250 km typically

• No subsea routers required

• Fiberoptic communication • High speed (1 Gbps) • Noise immune

• Power distribution 900 V – 3 kV AC


Distribution using Subsea Router Module (SRM)

Distribution using


(SRM)

• Typically 250 km with 3 kV AC

• One redundant pair of cables for many (20+) wells

• Fiberoptic communication for high speed (1 Gbps)

• Ethernet distribution locally (100 Mbps - 100 m)• Optionally modem to “repeat topside subsea”


(SRM) with topside

functionality “Topside

repeated subsea”



Fiber optic experience

Shallow waterShort distanceFibers to XT SCMCoP as backup

Deeper waterLong distanceFibers to XT SCMCoP as backup

Fibers to subsea routerCoP as backupEthernet to XT SCM

Fibers to subsea routerFiber only Ethernet to SCM

Fibers to central subsea routerCoP infield

Fiber repeaterOne-to-oneOne-to-many

2001, Fram Vest (Statoil)

2005, Ormen Lange (Shell)

2007, Tyrihans (Statoil)

2011, Pazflor (Total)

2013, Laggan Tormore (Total)


Bandwith / offset:

• 1GE (Gigabit Ethernet) � 40dB without in-line attenuation ~125 km

• 100M� 51dB without in-line attenuation ~ 190 km

• 10M�� 60dB without in-line attenuation . ~225 km

Capabilities are based on 0.2dB/km loss and 15dB margin

Assumptions:

• 0.2dB/km loss in fiber. Low loss fiber with 0.175dB/km loss is available.

• Conservative margins included:

• 5dB loss for ageing and variation in cable vs. umbilical length

• 10dB margin included.

Fiber optic communication system capabilities


AC parameters:

� Transmission 3.0 kVAC, 167km

� Distribution 600Vac, up to 6.6km

DC parameters:

� Transmission 1.2 kVDC, 167km

� Distribution 400Vdc up to 6.6km

Power - 3 kV AC vs 1.2 kV DC - 167 km example

AC DC

Transmission to single SDU, exp.

25% voltage drop for 1610W

Pair 16 mm2

redundancy A+B: 2 pair

1 pair 35 mm2

redundancy A+B: 2 pair

Distribution from SDU to single

load, exp. ΔU=5%, 300W

Pair 6 mm2

Red. A+B: 2 pair

Pair 10 mm2

Red. A+B: 2 pair

Efficiency Pout / Sin [%] With L-compensation: ≈19%

Without: ≈8%

No compensation necessary:

≈70%

• AC voltage is easily transformed, simple transformer instead of a complex DC/DC converter• AC has no issue with earth fault (would damage cathodic protection in a DC system)• AC has lower efficiency – but of marginal importance for a control system (low power)


Hydraulic System – Feasible at 600 km!

SCM LP header

Pilot header

Override

compensator

Exhaustvalve

DCVLP

LCF

COVLP

Umbilicalto HPU

Boost chamber

compensator

Spring chamber

compensator

R P S

Actuator

COVLP = Change Over Valve Low Pressure

DCVLP = Directional Control Valve Low Pressure

LCF = Last Chance Filter

• 7” gate valve: Opening: 42 sec, Closing: 17 sec

• Charging LP system: 60 hours

• Sequence: opening 6 wells within 3 hours.

• Quick dump valves for shut down


• Control Umbilical Cost Reduction is the key!• The rest of the control system is basically unchanged!

Long Distance Cost Reduction Technology Options


Control Buoy – Mossel Bay South Africa example

EM Field

EBF

Field

EH Field

Mosselbaai

FA Field

FAD Field

FBE Field

SDU 1

SDU 2

Control buoy

PLEM

LAT 1

LAT 2

FA PLATFORM

Controls gas/condensate production via a telecoms link to the host F-A Platform

Provides storage and injection facilities for chemical hydrate inhibition at the wellheads during and immediately after a well start up


• Communication on power cable, eliminates separate signal cables

• For very long distances: • Routers to reduce number of cables

• 3 kV AC to reduce cable cross section

Minimize Cable Count


• Hydraulic Pressure Intensifier (HPI)• Can be integrated part of SCM

• No high pressure at surface

• Proven in use • Topside

• Workover

• Subsea

Eliminate High Pressure (HP) Lines

MQC plate mounted HPI


Electric actuator technology:

• In general less sensitive to long offsets and water depth

Choke• Improved response time and resolution

• Simultaneous operations

• No choke hydraulic fluid consupltion

Large valves:• Less accumulation and fluid consumption (e.g. Manifold)

• Save space and weight by removing hydraulic actuators

All-electric Tree a future• Higher potential on long offsets

• Still maturing technology

Replace hydraulics with electric actuators

G2i Actuator G3 Actuator for subsea gas compression


Electric choke valve control:

• Quick and accurate

• Choke vibration information and exact position available

• Actuator retrievable independent of choke

• Eliminates largest hydraulic fluid consumer

Electric Choke Actuation

Hydraulic Stepping actuator G2i Electric Actuator


Manifold Valve Actuation – Distribution Simplified

Conventional Electro- Hydraulic Manifold All Electric Manifold


Application History – Electric Systems

2001 Statoil Statfjord SSP

16 eActuators and 4 eSCMsfor choke actuation

2006 Statoil Åsgard

2 eActuators for manifold

valve actuation

2006 Statoil Norne K

21 eActuators and 6 eSCMs

for choke actuation

2008 Petrobras Albacora RWI

21 eActuators and 7 eSCMs for

pump system valve actuation

2008 Woodside Pluto

1 eActuator and 1eSCM

for pig valve actuation

2009 Statoil Gjøa

6 eActuators for choke actuation

2009 Statoil Norne M

2 eActuators and 2 eSCMs

for pig valve actuation

2010 Petrobras Roncador

6 eActuators for water

injection choke actuation

2011 Statoil Smørbukk


2011 Statoil Vigdis NE


2011 Statoil Åsgard Gas Comp.

79 eActuators for choke and control valve actuation

Main TechnipFMC systems have been for manifolds, chokes and flow modules. 8 million operating hours recorded:

2001-2016, Total Units Sold:• 205 eActuators• 38 eSCMs

43 eActuators for choke and manifold valve operation

2015 Statoil Johan Sverdrup


Thank You!

long distance subsea control - norwep · pdf filelong distance subsea control | 4 field- and...

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