TOTAL and TECHNIP have decided to undertake the Evaluation Qualification (LEVEL 2) of the innovative technology of ELECTRICAL HEAT TRACE (EHT) as a solution for active heating of subsea flowlines within Electrically Heated Pipe-In-Pipe (EH-PIP), in order to face the production challenges of oil reservoirs with high flow assurance constraints (wax, gel and critical hydrate appearance temperatures). The EH-PIP is a standard reelable PIP system complete with trace heating cables wrapped in a helical pattern around the inner pipe (flowline), below the insulation. This paper reviews some of the processes that were undertaken to provide resolution of the identified uncertainties and demonstrate the high reliability of the system during construction, reel-lay installation and then during the various phases of operation, including line preservation and restart after planned or un-planned shut-down. The thermal qualification tests assess the thermal behavior of the EH-PIP, confirming its high heating efficiency (around 90%), and demonstrating its ability to maintain a uniform flowline temperature in all cases, including in the “degraded mode” with only one trace heating cable remaining operating. The Numerical Computational Fluid Dynamics (CFD) tools were validated against the full scale (OD) thermal test results, and allow the simulation of EH-PIP behavior in all field development conditions allowing further evaluation of the system performance. Furthermore, long term ageing tests on cables and associated connections have confirmed the long term integrity of the heating products.
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