Direct Electric Heating (DEH) is a cost efficient and environmentally sustainable flow assurance method that replaces the use of chemicals.
The presence of wax and hydrates in subsea flow lines is a major concern in the offshore industry. Wärtsilä DEH is based on using the thermally insulated flow line as part of the electric circuit, and allowing the electrical losses to heat the contents of the pipe.
Direct Electric Heating is today a mature technology that has been used for 14–15 years in Norwegian and West African installations. Wärtsilä has participated in the development of Wärtsilä DEH since the nineties, and today undertakes the design and supply of the complete topside Wärtsilä Direct Electric Heating package.
Wärtsilä Direct Electric Heating has been used for flow lines of up to 42 km, and with a power requirement of up to 12 MW.
Wärtsilä topside DEH package
The topside package comprises tailor made medium voltage components that control the current in the flow line, convert the load from single phase to a symmetrical 3-phase load, and compensate for the low power factor. Wärtsilä delivers electric and optic protection and control packages that have been specially developed for Wärtsilä DEH. The Wärtsilä Direct Electric Heating package can be installed in suitable indoor locations, or in outdoor locations within a steel or aluminium module with HVAC or water cooling. Wärtsilä DEH deliveries always include a special power system analysis to ensure its integrity with the platform system.
Scope of supply
Wärtsilä has been part of the DEH development in Norway since the nineties and we can provide:
- FEED Studies (Front End Engineering & DesignKey Benefits).
- Topside system design to meet subsea power requirement.
- Power system analysis.
- Tailor made Topside package.
- Project execution.
- Pre-commissioning/commissioning and start up assistance.
With the DEH system, asset owners will :
- Reduce CAPEXand OPEX.
- Have an environmentally sound flow assurance tool.
- Reduce or remove need of “anti-freeze” chemicals and belonging infrastructure/piping and storage.
- Enable single flow line without circulation possibilities.
- Enable marginal field to be profitable even if DEH is required continuously.
- Extend the lifetime of the field by managing water cut during tail production.
- Increase process plant efficiency through increased arrival temperature and remove/reduce requirement for removal of solvent during start up.
Direct Electrical Heating Flow Assurance Tools
“At Wärtsilä, we are passionate about optimising lifecycle value by offering precisely what each of our customers need. We can deliver on this promise because we provide integrated solutions, products and services for every phase of oil and gas exploration, production, transportation and refining worldwide – both onshore and offshore.
Even though this brochure is just a beginning to learn why we are involved in bringing more than 5 million barrels per day to the market, which is more than 6% of the total world oil production, it still demonstrates how we are able to customise our comprehensive offering in order to give customers a crucial competitive edge. Whatever the conditions, we deliver world-class efficiency, fuel flexibility and environmentally sound solutions.
In subsea flow lines, water content in the line can form ice-like structures called hydrate plugs. Wax appearance in flow lines is also a common flow assurance issue. Hydrates and wax appearance can reduce or stop oil production for weeks; therefore preventing the formation of these in pipelines is of major importance to the oil and gas industry. The traditional method for avoiding wax formations is by using chemicals.
Direct Electric Heating (DEH) is based on using the thermally insulated flow line as part of the electric circuit, and allowing the electrical losses to heat and keep the pipeline and its content above the critical temperatures. This is a cost efficient and environmentally sustainable flow assurance method that replaces the use of chemicals. DEH will also increase the process plant efficiency after planned or unplanned production stops.
With the DEH system, asset owners are able to :
• Remove or reduce storage and delivery requirements of anti-freeze chemical and infrastructure/piping.
• Enable single flow lines without circulation possibilities.
• Enable marginal fields, or fields with heavy or waxy oil, to be profitable even if DEH is required continuously.
• Extend the lifetime of the field by managing water cuts during tail production.
• Improve process plant efficiency through increased arrival temperature and remove/ minimize the requirements for removal of solvents during start-up.
• Reduce CAPEX and OPEX.
Expert Support Feed To Start-up
The Wärtsilä DEH solution includes :
• FEED studies.
• Power system analysis.
• Topside system design to meet subsea power requirements.
• Customized topside package.
• Project execution.
• Pre-commissioning/commissioning and start-up assistance.
Typical current range ~ 700A up to 1600A from topside (depends on project specific requirements).
Typical voltage range ~ 2–3 kV up to 26kV (depends on the length of the pipeline equipped with DEH).
Typical power range ~ 1000–12000kW.
Typical pipe length ~ 4–50 km (DEH for longer pipelines is under development).
Today, DEH is a mature technology that has been in use since year 2000. Wärtsilä DEH is also being used in West African installations. Wärtsilä has participated in the development of Wärtsilä DEH since the nineties, and today undertakes the design and supply of the complete topside Wärtsilä DEH package.
Wärtsilä has delivered 21 out of the 24 topside DEH systems installed in the world. The power ranges from 1 MW to 11 MW for pipelines, 4 km to 42 km :
• Åsgard platform, 6 pipelines (Statoil, Norway).
• Huldra platform, 1 pipeline (Statoil, Norway).
• Kristin platform, 6 pipelines (Statoil, Norway).
• Norne FPSO, 2 pipelines (URD and ALVE) (Statoil Norway).
• Kristin platform Tyrihans field, (Statoil Norway) 1 pipeline of 42 km, >10MW
Wärtsilä DEH is also being used in West African installations.
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