• Subsea Cooling

    NOV supplies both passive and active coolers to the oil and gas industry.

    Subsea Active Cooler 
    The subsea Active Cooler is a shell and tube cooler based on forced convection. The pump, motor and power control is the first qualified subsea design of its kind, where the oil filled motor is isolated from the pump by a magnetic coupling. The pump module including variable frequency drive motor controller, is designed for a subsea installation down to 3000 m. The motor is speed controlled, which makes it possible to operate the cooler within a predefined temperature range. The VSD and control system is fully redundant, and is qualified according to ISO 13628-6. 

    Main benefits for active cooling compared to passive cooling:

    • Use of field proven topside cooler technology
    • Compact, light and cost efficient
    • Controlled cooling through the incorporation of temperature sensors and control of forced convection pump speed
    • Lower surface temperature of the tubes gives reduced risk for scaling 
    • Flow assurance benefits
    • Provides a closed environment, which is advantageous for maintenance operations such as acid cleaning

    The NOV subsea active cooler has
    a wide range of possible applications, including but not limited to:
    • Inlet cooling to increase compressor efficiency period
    • Post-cooling to prevent pipeline overheating
    • Interstate cooling and/or anti-surge cooling

    Subsea Passive Cooler

    NOV has delivered a passive (tubular) heat exchanger designed to lower production gas temperature for improved service life. The passive heat exchanger (cooler) provides a thermal processing function, i.e. cooling. The Passive Cooler features field proven technology. Heat transfers from the hot medium (gas or liquid) inside a pipe to the less warm water outside of the pipe. The Passive Cooler overall dimensions (length, width and height), pipe dimension and stacking configuration are all chosen to amplify natural convection and introduce minor forced convection. The analysis was conducted by iterating between Ledaflow for the internal pipe flow and CFX for the natural convection currents in the sea water.

    • Lowering production temperature to customers need
    • Field proven  technology
    • Reduced risk for scaling

    Why subsea cooling?  
    Subsea cooling in combination with liquid/gas separation provides the ability to produce at lower reservoir pressure, thus offering radically better flow assurance and higher performance, reduces HSE risks and lower development cost options. NOV has designed a Subsea Cooling System with focus on reliability, optimized cooling process and temperature control, giving advantages in size, weight and controllability.  
    Our robust Subsea cooling system enables:  
    • Subsea gas dehydration
    • Inlet cooling to increase compressor efficiency
    • Post-cooling to prevent pipeline overheating
    • Inter-stage cooling and / or anti-surge cooling
    • Gas/Liquid separation