IWOCS
Intervention workover control systems
A fully independent service solution across the life of field Proserv provides fully integrated intervention workover control systems (IWOCS), which deliver temporary well control during subsea installations, workovers and abandonments. With over 40 years’ of experience, we have executed more than 700 monitoring, control and retrieval projects, making us the global leader in design, manufacturing and rental. With a global fleet of IWOCS units comprising a wide range of size and functionality, we can offer our clients a comprehensive unlimited package solution to meet each field’s unique configuration.
Global operational hubs 16 HPU units up to 36 functions on fleet of umbilicals Compliant DNV and NORSOK compliant
Proserv IWOCS
Benefits of IWOCS
When it comes to subsea intervention, we understand that there are major advantages to OEMs, operators and subsea contractors having a fully flexible choice of options. With both shallow and multiplexed deepwater options available, Proserv’s array of custom built and rental IWOCS equipment provides well control during subsea installations and workovers.
  • Equipment configured to your requirements - reelers, HPU, etc
  • Design and build of new IWOCS
  • IWOCS rental system - long and short terms rental options
  • Preservation and maintenance of client-owned equipment
  • Full range of on-site testing and flushing of equipment with full system integration testing (SIT) scopes
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    The benefits
  • Provide power and communication subsea, local to the tree
  • Not restricted by weather as there is no umbilical connection that requires disconnection in high seas
  • Designed around standard ROV technology and can be used with any intervention vessel, rig or drill ship that has a work class ROV TMS
  • We are an independent supplier - we have the flexibility, knowledge and experience to work on any OEM equipment
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    IWOCS SOlutions Proserv can design and manufacture a comprehensive range of IWOCS to suit varied client needs. Our in-house engineering capabilities are backed up by a responsive team ensuring critical projects are carried out on time and within budget. To ensure our IWOCS can meet exact client specifications and requirements, we ensure that our equipment is fully interchangeable and can be integrated into different types of workover scenarios to suit any tree or intervention system. Custom capabilities and systems are also offered, and our IWOCS are compatible with third-party equipment for full flexibility.
    9 Function Pneumatic IWOCS Hydraulic Mini Panel Compact and efficient hydraulic control solution
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    19 Function Pneumatic IWOCS Hydraulic Power Unit Reliable and robust hydraulic control solution
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    20 Function Electro-Pneumatic IWOCS Hydraulic Power Unit Advanced hydraulic power solution
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    20 Way Hydraulic Power Unit Efficient and versatile hydraulic control solution
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    20 Way Umbilical Hose Winch Versatile solution for hydraulic control and subsea operations
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    Pneumatically Operated Electrical Down Line Mini Reeler Compact and efficient solution for subsea electrical cable handling
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    Pneumatically Operated Umbilical Mini Reeler Compact and efficient solution for handling smaller umbilicals
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    Pneumatically Operated Umbilical Reeler DNV Purpose-built reeler for deployment, retrieval, and storage of umbilicals
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    Pneumatically Operated Umbilical Reeler Purpose-built solution for umbilical deployment and retrieval
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    Umbilical Deployment Basket Flexible deployment solution for IWOCS applications
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    9 Function Pneumatic IWOCS Hydraulic Mini Panel This IWOCS hydraulic mini panel features pneumatically driven pumps for both the LP and HP functions. Panel-mounted gauges, regulators, ball valves, and needle valves provide control and monitoring for all nine functions. The units also feature a hydraulic flow meter on the low-pressure supply circuit, allowing the accurate measurement of function flow. There is an accumulator connection port on the panel bulkhead, which can be used to add accumulation to the system. Additional accumulation reduces Xmas tree valve response times and ensures safety with a store of hydraulic fluid under pressure in case of compressed air supply failure. The panel functions are configurable to client requirements, making them ideal for Xmas tree running/testing, subsea running tool operations, and SITs, where a full HPU may not be needed. An optional stand-alone ESD system with remote stations is available for up to four functions. Technical Details
    Low pressure system 3,000 psi max working pressure
    High pressure system 10,000 psi max working pressure
    Low pressure lines LP1 - LP7
    High pressure lines HP1 - HP2
    Low pressure flow (@3,000 psi) 10 l/min
    High pressure flow (@1,000 psi) 1.2 l/min
    Low pressure flow totaliser
    High pressure connections JIC 4
    Low pressure hot line Suitable for addition of accumulator bank
    Low pressure pump Haskel GSF60
    Low pressure connections JIC 6
    High pressure pump Haskel AW100
    Recirculation filter 3 micron return filter and sample point
    Reservoir Capacity 60 litres
    Gross weight 500 kg
    Dimensions 1,390 × 600 × 1,200 mm
    19 Function Pneumatic IWOCS Hydraulic Power Unit This IWOCS hydraulic power unit features air-driven pumps for the LP, HP, and VHP functions, with pneumatic pump backup for the LP and HP functions. Panel-mounted gauges, ball valves, and needle valves provide control and monitoring for all 19 functions. A Walther multi-function hydraulic connection plate enables function connection to the chosen reeler via a multi-core deck jumper. The unit is fully containerized, providing a safe and weather-tight work area. Accumulators on both LP and HP circuits allow faster Xmas tree valve operations and an accumulated store of hydraulic fluid in case the compressed air supply is lost. The panel functions are configurable to client requirements, and a stand-alone ESD system with remote stations can be added for up to four functions.
    Technical Details Hydraulic output capacity
    High pressure circuits 10,000 psi max working pressure
    Low pressure system 3,000 psi max working pressure
    Very high pressure 20,000 psi max working pressure
    Dimensions 3,000 × 2,420 × 2,650 mm
    Fluid Compatibility
    Fluid compatibility Suitable for both water-based glycol and light oil-based hydraulic fluid types with kinematic viscosity <15 cSt @ 40°C.
    Compressed Air Input
    Min pressure 100 psi
    Weights Dry
    Tare 2,500 kg
    SWL 7,050 kg
    Gross 9,550 kg
    HPU Accumulator Pre-Charge Standard Pressures
    2 × HP 2,600 psi (variable)
    4 × HP 1,812 psi (variable)
    Electrical Input
    Electrical input CTE 110VAC, 16 Amp, 1ph, 50/60Hz
    20 Function Electro-Pneumatic IWOCS Hydraulic Power Unit This IWOCS hydraulic power unit features an electric-driven pump for LP functions and a pneumatic pump for HP functions. Panel-mounted gauges, ball valves, and needle valves provide control and monitoring for all 20 functions. A Walther multi-function hydraulic connection plate ensures full function connection to the chosen reeler via a multi-core deck jumper. The unit is fully DNV containerized with separate control and pump room sections, providing a safe and noise-reduced work area. The panel functions are configurable to client requirements, and a stand-alone ESD system with remote stations can be added for up to four functions. Technical Details High Pressure System
    High pressure system 10,000 psi MWP
    High pressure lines HP9 – HP16; HP Hot Lines HP17 – HP20
    High pressure output 1 LPM
    Min working pressure 7,500 psiG
    Max working pressure 10,000 psiG
    Filter size 3 micron
    Low Pressure System
    Low pressure system 3,000 psi MWP
    Low pressure lines LP1 – LP8
    Low pressure output 35 LPM
    Min working pressure 3,000 psiG
    Max working pressure 4,000 psiG
    Filter size 3 micron
    Suitable for both water-based glycol and light oil-based hydraulic fluid types with kinematic viscosity <15 cSt @ 40°C. Additional Specifications
    Minimum air pressure 75 psiG
    Electrical requirements CTE 400VAC, 24 Amp, 3ph, 50/60Hz
    Input connector type 130VAC 16A-4H 2P+E
    Dimensions 3,660 × 2,400 × 2,750 mm
    Weight
    Tare
    SWL
    Gross
    20 Way Hydraulic Power Unit Efficient and versatile hydraulic control solution This 20-function workover control panel supports 11 functions at 5k psi and 9 functions at 10k psi. It includes a fluid circulation pump with 3-micron filters and sampling points, ensuring clean and efficient operation. The system features a digital flowmeter for LP and HP lines and a built-in 15k psi chart recorder for precise monitoring. Additionally, the HPU is fitted with hotstab connections for HP, LP, and return lines. Technical Details
    Reservoir700 litres
    Low pressure accumulator4 each × 37 litres
    Low pressure max working pressure5,000 psi
    High pressure accumulator2 each × 12 litres
    High pressure max working pressure10,000 psi
    LP and HP pumps (two each)Haskel air driven pump
    Lighting220 volts
    Tare weight3,500 kg
    Net weight1,500 kg
    Gross weight5,000 kg
    Proof load10,000 kg
    Dimensions320 × 250 × 270 cm
    StandardsLloyds Bs 7072 / IEE
    Rated zoneZone 1
    Haskel Low Pressure Pump (2 Sets)
    Assembly noAW-60
    Nominal ratio60:1
    Max pressure9,800 psi liquid
    Date manufacturedAugust 2007
    Haskel Nitrogen Pump
    Model numberACD-62
    TypeSingle stage double acting
    Max gas in9,000 psi
    Max gas out9,000 psi
    Haskel High Pressure Pump (2 Sets)
    Assembly & serial noAW-100 / 807-921
    Nominal ratio100:1
    Max pressure16,500 psi liquid
    Date manufacturedAugust 2007
    Oaler Fawcett Christie Cylinder (2 Sets) High Pressure Side
    Charged to4,200 psi
    Size12 litres
    Model1205K-DC-694
    Max working pressure690 bar
    Haskel Circulating Pump
    Assembly numberATV-4
    Nominal ratio4:1
    Max pressure1,200 psi liquid
    ManufactureAugust 2007
    Oaler Fawcett Christie Cylinder (2 Sets) Low Pressure Side
    Charged to2,300 psi
    Size37 litres
    ModelAC-3703F-CZ-344
    Max working pressure345 bar
    20 Way Umbilical Hose Winch Versatile solution for hydraulic control and subsea operations The umbilical reel is designed to meet customers' hydraulic control requirements for horizontal and vertical well completions. It supports multiple hydraulic connections for operations and can also be used to control subsea tree functions and LMRP/BOP control system functions. The reel is equipped with a spool gear and gauge panel on the drum side, providing a locking mechanism for all 20 functions. Additionally, it includes an electrical plug for umbilical electric cables, with all moving parts fully guarded by wire mesh guards. Technical Details
    Drum capacity350 m × 20 way umbilical
    Connectors24 Way Walter stab plate and live center
    Drive System18 HP air motor with SAAR multi disc brakes
    Brake pull test@ 1 Ton
    Reduction mechanism60:1 Gearbox
    Bearing ratings14,000 kgf dynamic and 10,000 kgf static load
    Umbilical length300 m
    Air supply120 psi
    Working pressure10,000 psi
    Dimensions300 × 300 × 300 cm
    Tare weight3,400 kg
    Max gross weight10,000 kg
    CertificationAustralian standards Built to Lloyds BS7072/IEE
    Pneumatically Operated Electrical Down-Line Mini-Reeler Compact and efficient solution for subsea electrical cable handling The pneumatically operated electrical down-line mini-reeler is designed to handle subsea electrical cables of varied configurations. Its small footprint and ease of operation make it ideal for space-constrained environments. Common applications include Xmas tree and completion down-hole sensor duties, and the mini-reeler can be quickly mobilized, including electrical IR testing. Equipped with an electrical junction box, the reeler can be customized with a connection or pig-tail to client requirements, enabling fast and easy connections to the down-line. The motor-driven system features an automatic brake, while input air is filtered, lubricated, and regulated to the correct pressure. A joystick on the control panel provides precise speed and direction control, and a safety locking pin prevents drum rotation during transport. Technical Details Compressed Air Input
    Max volume60 cfm
    Max pressure8 bar (120 psi)
    Dimensions1,420 × 1,450 × 1,550 mm
    Weight
    Tare weight800 kg
    Payload weight4,000 kg
    Gross weight4,800 kg
    Pneumatically Operated Umbilical Mini-Reeler Compact and efficient solution for handling smaller umbilicals The pneumatically operated umbilical mini-reeler is designed for handling smaller umbilicals with up to eight cores, depending on the outer diameter. Its compact footprint and ease of operation make it ideal for confined spaces. Common applications include Xmas tree running, pressure testing duties, high-pressure hydrostatic testing, and fill/flushing of client-specified fluid to SAE 4059 Rev. E Class 6B-F. The motor-driven system features an automatic brake, and all input air is filtered, lubricated, and regulated to the correct pressure. A joystick on the control panel provides precise speed and direction control, and a locking pin enhances safety by preventing drum rotation during transportation. The HP system operates at 10,000 psi (690 bar), with up to eight inlets and outlets. Connections include four JIC bulkhead fittings, with up to six bulkhead outlets featuring pressure gauges and two-way needle valves for lock-in functionality. Technical Details Output Capacity
    High pressure system10,000 psi (690 bar) MWP
    Compressed Air Input
    Minimum volume60 cfm
    Maximum pressure16 bar (232 psi)
    Physical Dimensions
    Dimensions1,810 × 1,600 × 1,840 mm
    Tare weight1,500 kg
    SWL weight2,500 kg
    Gross weight4,000 kg
    Suitable for both water-based glycol and light oil-based hydraulic fluid types with kinematic viscosity <15 cSt @ 40°C.
    Pneumatically Operated Umbilical Reeler DNV Purpose-built reeler for deployment, retrieval, and storage of umbilicals The pneumatically operated umbilical reeler is designed for the deployment, retrieval, and storage of umbilicals that route hydraulic supplies from topside to subsea Xmas trees. A protective frame encloses the pneumatic motor, gearbox chain drive, control panel, and bulkhead interface, ensuring safety and durability. Protective meshing guards moving components against ingress. The reeler’s spooling mechanism is powered by a pneumatic radial piston motor connected to a reduction gearbox for optimal drum speed. The failsafe lever control valve manages speed and direction, automatically applying a brake when released. For safe handling, the reeler is equipped with padeyes, a sling set, and forklift pockets. Padeyes are rated for 8.5-tonne shackles to lift the gross weight. The umbilical is interchangeable and configured per job requirements, providing flexibility across various operations. Technical Details: DNV Z7-1
    Dimensions2.9 × 2.84 × 3.15 m
    WeightGross 10,000 kg, Tare 6,000 kg
    Lifting optionsSlings and forklift pockets
    Spooler accessOpen from front and rear, caged restriction from sides and above
    Power supplyPneumatic
    Fitting1" Crows foot connection
    Motor typeGlobe RM310 motor
    Motor RPM maximum1,800 rpm
    Power output7.5 kW at 8 bar
    Max torque at 6 bar43 Nm at 1,800 RPM
    Gearbox typeBrevini EC4090 / MNI / 400 / 00 / B3
    Gearbox ratio400:1
    Drive sprocket12B-1 X33T WP
    Chain size3/4" pitch
    Motor operation pressure6 bar
    Motor max pressure8 bar
    Motor max flow rate440 cfm
    Operational controlsMechanical pneumatic
    Unit colourProserv yellow / grey
    LubricantKilfrost 400
    Pneumatically Operated Umbilical Reeler Purpose-built solution for umbilical deployment and retrieval The pneumatically operated umbilical reeler is designed for deployment, retrieval, and storage of umbilicals that route hydraulic supplies from topside to subsea Xmas trees. The unit’s protective frame encloses the pneumatic motor, gearbox chain drive, control panel, and bulkhead interface, with meshing to guard moving components. The spooling mechanism is powered by a pneumatic radial piston motor through a reduction gearbox, achieving optimal drum speed. A failsafe lever control valve manages speed and direction, applying a brake when released. Padeyes with a sling set and forklift pockets provide safe handling. The padeyes support 8.5-tonne shackles, lifting the gross weight. Interchangeable umbilicals offer flexibility for various operations, with configurations tailored to specific jobs. Technical Details
    Dimensions2.9 × 2.89 × 3.27 m
    WeightGross 10,000 kg, Tare 6,000 kg
    Lifting optionsSlings and forklift pockets
    Power supplyPneumatic
    Fitting1" Crows foot connection
    Motor typeGlobe RM310 motor
    Power output7.5 kW at 8 bar
    Max torque at 6 bar43 Nm at 1,800 RPM
    Gearbox typeBrevini EC4090 / MNI / 400 / 00 / B3
    Gearbox ratio400:1
    Drive sprocket12B-1 X33T WP
    Chain size3/4" pitch
    Motor operation pressure6 bar
    Motor max pressure8 bar
    Motor max flow rate440 cfm
    Operational controlsMechanical / pneumatic
    Unit colourProserv yellow / grey
    LubricantKilfrost 400
    Umbilical Deployment Basket Flexible deployment solution for IWOCS applications The IWOCS Umbilical Deployment Basket is a versatile solution designed to adapt to varying client requirements. It supports up to two hydraulic flying lead parking plates from any manufacturer and accommodates multiple electrical flying lead parking receptacles within its robust frame. Designed for deployment on existing guidewires above the BOP/XT, the basket can be further modified with modular components to allow seabed deployment or direct interfacing with other subsea infrastructure. Each Proserv umbilical deployment basket is equipped with an emergency umbilical severance system, ensuring a quick and safe disconnect of the WOCS during emergencies. Technical Details
    Tare weight150 kg
    SWL weight450 kg
    Gross weight12,000 kg
    Dimensions2.70 × 0.88 × 1.30 m
    Rental & Services
    IWOCS Rental Equipment & Services IWOCS Rental Equipment & Services Full rental service, preservation and maintenance We offer a comprehensive range of rental equipment and specialised services to support offshore campaigns. From providing cutting-edge rental solutions to delivering expert maintenance support, we ensure reliable and efficient operations for IWOCS equipment in even the most demanding environments. Learn more about our IWOCS rentals and services
    IWOCS Rental Equipment We offer a comprehensive range of rental equipment to assist in offshore campaigns. Our rental inventory includes HPUs, reeler systems, umbilicals, and deck jumpers, along with deployment baskets, sheaves, and emergency disconnect systems. All of these are supported by highly skilled offshore personnel, ensuring smooth integration with subsea systems like Christmas trees, landing strings, and control systems.
    Hydraulic Panel
  • 7 x 3,000 psi functions
  • 2 x 10,000 psi functions
  • LP & HP flowmeters
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    Hydraulic Umbilical
  • 1 - 24 core
  • Up to 12,500 psi MWP
  • 300m - 1000m
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    Electric Downline
  • 2.5 SQ MM twisted pairs
  • Various electrical crossovers can be supplied
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    Umbilical Sheave
  • Various sizes to suit a single Electric Downline to 24 core Umbilical
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    IWOCS Services - Preservation and Maintenance Our IWOCS division specialises in a wide range of subsea and topside services, including Test & Assembly, FAT/SIT, Topside Wellhead Control Panels, and Preservation Storage & Maintenance. These services are designed to provide operators with peace of mind and an efficient, long-term approach to managing their equipment. Using our AEGIS (Asset Enhancement Global Intelligence Solution) technology, operators can log in to monitor the status of their equipment in real-time. This capability allows for better forecasting of maintenance activities, reduced costs, and maximised efficiency throughout the equipment’s lifecycle.
    Test & Assembly
  • New built and refurbishment of subsea hardware
  • Pressure testing and flushing services
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    FAT/SIT
  • 3 x SIT pads rated up to 100 tons
  • Onsite technical / engineering support
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    Topside Wellhead Control Panels
  • Refurbishment of Topside HPU’s and Control Panels
  • Experienced small bore tubing technicians
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    PSM
  • Preservation, storage and maintenance providing total care of assets throughout their life
  • Three-tier system from basic checks and preservation to a full overhaul and recertification
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    Our people
    People are at the core of our IWOCS solutions
    RELIABILITY Our IWOCS team has in excess of 1 million man-hours executing monitoring, control, and retrieval projects. We pride ourselves on offering clients the opportunity to have a fully independent service solution, delivered by the most experienced IWOCS team. Our highly experienced offshore service personnel deliver IWOCS solutions built to exact client specifications and requirements. Our team has worked in every part of the globe, on the full range of subsea trees and interventions, as part of long-term project rotations and short-term ventures. We work alongside our in-house engineers to support our clients from project kickoff through to project completion. Local operations and aftermarket hub:
  • Test and assembly facilities
  • 10,000 square feet of workshop space
  • Test cells, clean rooms, and external SIT area
  • 24/7 cover
  • Deployment of equipment and personnel within 48 hours
    •  Where we work
    Where we work
  • Where we operate
  • Our Locations
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    Case Studies
    IWOCS: Kessog project Proserv was contracted by TOTAL E&P Ltd to provide an integrated workover control system (IWOCS) capable of operating on a high pressure/high temperature wellhead.
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    INTERVENTION WORKOVER CONTROLS: KESSOG PROJECT Project Background Proserv’s control systems have become increasingly complex over time, driven by the need to meet new regulatory requirements from both a safety and environmental perspective. Early equipment utilised simple direct hydraulic systems, operated from manual hydraulic control valves located on a small control panel supplied from the rig system. These systems have now been developed into the integrated workover control systems (IWOCS) we see operating in the North Sea continental shelf. These utilise fail-safe pilot hydraulic systems and, in some cases, are provided with remote-operated panels and multi-level sequenced shutdown systems. Solution Proserv was contracted by TOTAL E&P Ltd to provide an integrated workover control system (IWOCS) capable of operating on a high pressure/high temperature wellhead, while providing electro-hydraulic controls capable of interfacing with a third-party master control station. Right from the beginning of the project, Proserv was faced with four key challenges associated with the Kessog field:
  • High pressure - wellhead application (12,500 psi)
  • High temperature - wellhead application (125 degrees C)
  • Christmas tree deployment via diving support vessel (DSV)
  • Well completion from Sedco 714 drilling rig
    •  By adopting a one-Proserv approach and evaluating the project specifics based upon their own individual specifications, Proserv was able to have all associated equipment designed and manufactured. A pre-mobilisation system integrity test (SIT) was also carried out to ensure safety, quality, and operational parameters were met within the specified timeframe assigned by TOTAL. Scope The system requirements for this particular workover consisted of one hydraulic power unit (HP & LP functions), a 14-core umbilical reel, umbilical deployment basket, and hydraulic cutter. Conclusion Proserv was able to deliver the project on time through a fast-track system. With focused project management along with dedicated team technicians, the entire operation was carried out effectively throughout. In-depth analysis was available during the project through a variety of briefs, de-briefs, toolbox talks, etc. By performing successfully on this project, Proserv was able to gain further experience in the field as well as strengthen their relationship with TOTAL E&P. The Benefits
  • Compact design of the IWOCS keeps equipment footprint to a minimum, which is essential on a crowded drill floor.
  • Air-operated pumps within the HPU eliminated the risks of an electrical system and kept the IWOCS within the applicable zone rating.
  • High pressure and high temperature design of the umbilicals were made specific to the project requirements, ensuring efficiency when controlling the well.
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    The Team
    Lisa Urquhart Senior Service Delivery Manager
    John Sutherland Account Manager