Subsea Control Systems

INGENIOUS SIMPLICITYSimplifying Subsea ProductionProserv’s direct hydraulic and multiplexed production subsea control systems provide control and shutdown of subsea wells together with robust communications that enable the topside management and monitoring of subsea activities.

We specialise in subsea control modules and communication distribution and surveillance equipment for offshore production optimisation, control and monitoring to customers around the globe. Our subsea control and monitoring solutions can be installed and interfaced to subsea trees from all major manufacturers with open architecture communications and modular designs for adaption to suit specific project requirements.

Our innovative range of services are briefly outlined on the following pages, however if you require further information please email us or check our website for regional contact details: www.proserv.com

Introduction

MechanicalProserv’s integrated system provides the required monitoring, control and shutdown functions by means of multiplexed electro-hydraulic control. Communications are provided using communications-on-power modems between a surface Master Control Station (MCS) and Subsea Control Module (SCM) via a composite services umbilical and appropriate subsea distribution unit(s). In addition to the control module, a data module may be used to bring open communications to a field to integrate Proserv and third party communication devices, for example flow metering or downhole sensing.

The data or control module system is designed for deployment and intervention by means of a Remotely Operated Vehicle (ROV) or diver intervention using a similar module. Assisted guideline and non-guideline running tools or funnels are available with ROV assistance in very deep water. These feature a simple sliding plate design that locks down the mechanism.

Electric and hydraulic connections to the ROV SCM are made using low force connectors, mounted on the base of the unit, which connect when the unit is locked into place and via a stab-plate arrangement for diver installed systems.

The MCS provides the subsea power and communications interface between the installed subsea control module(s), the platform/vessel control system and any other third party systems, via serial or Ethernet based network connections. The modular MCS provides a compact and flexible solution for ease of integration into new or existing equipment rooms. Equipment can also be supplied for hazardous area installation.

“A modular design concept, electro-hydraulic multiplex subsea control system incorporating proven technology and qualified components to minimise both CAPEX and OPEX costs.”

The SCM housing is filled with dielectric fluid prior to installation and is pressure compensated to safeguard against over or under pressurisation.

The SCM housing is fabricated from structural steel manufactured to BS EN 10 025 Grade Fe430C or Fe510 D1/D2 and finish painted to our standard subsea paint specification. All hydraulic and electric couplings are manufactured from 316 stainless steel or better.

The hydraulic system consists of self latching solenoid operated shear seal directional control valves mounted on a stainless steel block manifold, with single or dual hydraulic supplies dependent on client’s specifications. Electrically held-open valves can also be mounted in this unit for Emergency Shutdown (ESD) system functionality if required.

Individual High Pressure (HP) and Low Pressure (LP) hydraulic supply filters are mounted within the control module maintaining fluid cleanliness specifications.

Both hydraulic supplies have pressure transducers to indicate system pressure within the control module.

The tree valve hydraulic actuator inferred status is sensed by individual pressure transducers, integral to the directional control valves, which relay the function line pressures to topside where they may be displayed on the MCS screen and made available to the Distributed Control System (DCS)/platform control system.

An accumulator can be accommodated within the control module to help prevent pressure drop during valve operations on large step outs. Alternatively, separate subsea accumulator modules can be provided to maintain local pressure levels.

Standard Functions/Features

• Four HP hydraulic outputs • Twenty two LP hydraulic outputs • Dual HP and LP hydraulic inputs via shuttle valve • HP and LP ESD valve • Directly mounted digital control valves to single manifold block • HP and LP vents to sea or closed loop returns

Subsea Control Module

The Subsea Electronics Module (SEM) has been designed to be surface removable and replaceable without the need to disturb the module’s hydraulics chamber. It houses power, communications, control and third party interface electronics. The housing provides a one-atmosphere dry nitrogen purged environment located within the main SCM housing. Proprietary penetrators provide connection to the SCM and external tree instrumentation.

Communications between surface and subsea are by means of a redundant Intelligent Well Interface Standardisation (IWIS) Point-to-Point Protocol (PPP) compliant power line carrier modem providing Ethernet, RS232 and RS4XX with open protocol connectivity. Communications can be implemented to suit comms-on-power, separate comms-and-power or fiber optic that is dependent on client and application requirements. A configurable frequency band of operation (50 to 690 kHz) enables integration and co-existence with other legacy powerline modems to develop existing system extensions of control and/or data devices. The available system bandwidth range is 1 to 390 kbps, dependant upon umbilical cable characteristics.

The SEM provides control and data monitoring via a dedicated embedded processor with scalable and configurable input/output channel configurations to suit client and application requirements. Communications for data retrieval or control commands with the SEM processor is by Modbus® RTU protocol. In addition, the SEM incorporates internal diagnostic monitoring for internal power supplies, environmental, processor status and communications.

Extensive system configuration and diagnostic tools and displays are available to the users via the topside MCS workstation.

Note: User levels of security access are applied to ensure the safety and ease of use for the system.

SEM Standard Functions Standard

• Unit has single SEM (dual SEM optional) providing 4 to 20 mA (standard), discrete input/output instrumentation and controls interfaces • Fully dual redundant power supplies and communication channels • Housekeeping functions including internal voltage/current monitoring, internal pressure, temperature and humidity • Mounting, power and communication interfaces for third party devices, IWIS compatible • Fast scan analogue data capture with configurable sample rates • Ethernet, RS232 and RS4XX (2 off) communication ports; fully IWIS PPP compatible for true open architecture • Quad Access Control provides media synchronisation to enable two pairs of quad to be individually used, avoiding cross-talk issues • Multi-drop architecture with individual remote device frequency and bit-rate configuration/selection to optimise system data and control performance

• Carbon steel fabricated housing, painted to standard subsea paint specification • Installation and intervention by ROV assisted running tool, funnel or diver onto mounting base • Dielectric fluid filled pressure compensated housing and atmospheric SEM housing • Designed for use up to 3000 meters of water • 1.5 atmosphere nitrogen filled electronics housing with pressure and temperature monitoring • Dual HP and LP supplies, incorporating individual hydraulic supply line filters with B3 = 200 rated elements • Control of hydraulic valve actuators by stainless steel body, sheer seal type solenoid valves • Earth strap for bonding and low resistance connection to the module mounting base on the manifold cathodic protection system • Connection points legibly identified by proprietary laminated nameplates • Stand alone sacrificial anodes for cathodic protection will be provided based on isolation for six months on the seabed • Two outgoing electro-hydraulic ROV/diver stabplates both mounted on SCM mounting base

Electronics External

Topside DCS and third party interfaces:

• Serial, Ethernet, fiber-optic solutions with a full range of standard industry protocols available

Subsea interfaces:

• Transparent RS232, RS4XX and Ethernet connectivity • Profibus, CANbus, Modbus RTU and TCP implemented • Full IWIS PPP compliant interface • Fiber optics

Communications

A range of test equipment is available for rent or to purchase:

• Cable simulators • Test MCS

The test stand (shown above without enclosure panels) is designed for onshore/offshore testing and commissioning, or for use on vessel prior to deployment of the SCM. The stand is a fully integrated unit consisting of hydraulic power unit, pumps, filters, tree valve actuator simulators and self contained controls computer panel.

Design Criteria Test Equipment

Water Depth

Environmental Data

Subsea Equipment Design

System Pressures and Fluid

Electrical

Operating temperature range (°F/°C)

Vibration

Shock

EMC iaw ISO 13628-6

iaw ISO 13628-6

iaw ISO 13628-6

Surface unit = 23 to 104 (-5 to 40)Subsea unit = 23 to 104 (-5 to 40)

3,000 m LAT

Design life

Intervention

SCM weight

SCM size (in/mm) (L x W x H)

SCM housing Pressure compensated, dielectric fluid filled

(lb/kg) In air, 1874 (850)In water, 1323 (600) approximately

33.5 x 33.5 x 3 (850 x 850 x 75), excluding mounting base

ROV or diver deployment and intervention

25 y

High pressure

Low pressure

Control fluid cleanliness

Control fluid

Supply filtration Integral single B3–200 rating elements (3 micron)

NAS 1638 Class 6

Water based biodegradable, open loop or petroleum based synthetic mineral oil (standard)

(psig/barG) 5k (345) MWP

(psig/barG) 15k (1034) MWP

Analog ue

Discrete

Communications

Power supply

Comms-on-power, comms-and-power and/or fiber optic

110, 230 or 480, 50/60 Hz single phase (nominal), 24 VDC (option)

24 VDC, 0.5 to 8 A (maximum) output configurable24 VDC input configuration available

4 to 20 mA (standard) 12-bit, other configurations available

MountingSubsea tree or manifold structure (ROV to API 17 H or diver)

info@proserv.comwww.proserv.com