Direct Electrical Heating: Single Pipe Vs Pipe-In-Pipe: Is a Double Wall Worth It?

Abstract

The High-Performance DEH-PiP is a new technology for electrical heating of subsea tie-back flowlines, that minimizes disturbances to the construction and installation process wrt. to standard PiP avoiding the use of internal heating cable, while reaching the same electrical efficiency as e.g. Electrical Heat-Traced (EHT) pipe-in-pipes. It thus boasts a much higher efficiency than a Wet Insulated DEH pipe. However, no comparison has been done so far on the CAPEX needed. Is a DEH PiP worth its value? Is the second pipe wall worth the expense? The aim of this paper is thus to present a novel comparative study between DEH-PiP and a traditional Wet Insulated DEH single pipe A complete engineering study has been made (flow assurance, pipeline design, electrical engineering, installation engineering) based on real cases. Full EPCI costs have been evaluated, local content for fabrication quantified, and associated carbon emissions as well during operations The study concludes that High Performance DEH Pipe-in-Pipe is difficult to compare to Wet insulated Single pipe The technology was 3% more expensive in CAPEX on the 30km tieback studied, but the margin remains small, and other factors may influence the conclusion. The two technologies remain comparable in a 20-40km range. A DEH-PiP offers more thermal and power efficiency, and other benefits such as greenhouse gases emissions savings. Operational downtime and production fluid properties should also be considered in decision making.