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As oil and gas production moves into deeper, more hazardous environments; as the need for production facilities receive increasing pressures on costs and as the effects on the environment are more and more in the public eye, there is the growing need for full subsea processing facilities.
Whilst the subsea segment of the upstream Oil and Gas market is quite mature, the journey to the sea bed is a long one. Converteam has since 1996 been present in preparing for the phase where a subsea project utilizing full subsea power distribution which is required for process plant which has a cable length greater than is sensible for a topside drive solution, i.e. greater than 50km.
A subsea power supply system using variable speed drives requires the following system components:
- Subsea transformers
- Subsea switchgear
- Subsea drives and controls
- Subsea motors.
Converteam’s approach is for the subsea system to be considered as a complete network, from point of grid connection to mechanical equipment coupling even though items in the system may not be supplied as part of Converteam’s scope. Converteam’s capability includes complete electrical system modeling with network, fault loading and harmonic analysis. With this approach, the operator can be assured of the highest reliability.
Since the 1980’s, as a pioneer in High Speed solutions, Converteam has been developing a range of high speed motors which meet all of the speed and performance requirements of pump and compressor systems. Today, having successfully commissioned more than 40 high speed motors, which drive the compressor directly with no intermediate gearbox, Converteam is the world’s leading supplier of high speed solutions. This solution is now available for subsea pumps and compressors.
Subsea transformers are an established solution for subsea power and can be easily incorporated into the subsea system.
Adapting switchgear for subsea applications involves the utilization of standard breakers with control systems which are appropriate to a subsea system. This industry standard equipment is then packaged or marinized in a vessel suitable for the depths of water applicable to the project location.
The control systems used for subsea use need to reflect the high reliability needed for a system which will be located on the sea bed for more than 5 years and having a level of redundancy which will satisfy a demanding MTBF requirement.
The subsea drive is designed according to the project requirements, depending if it is for pumping or compression or a combination of the two. The configuration shall be in accordance with the subsea process contractor’s requirements with all equipment located in one vessel which offers highest MTBF or in separate vessels to achieve easy retrieval.