Active heated pipe technologies are enabling solutions for field developments allowing cost effective management of flow assurance to overcome specific challenges like longer distance tie-backs and greater water depths.
This paper introduces wax and hydrate issues and conventional approaches to manage them. It highlights the need for other approaches, such as active heating technologies, to reach longer tie-back distances and greater water depths.
It reviews Direct Electrical Heating (DEH), Electrically Heat-Traced Flowline (EHTF), and active heated flowline bundles comprising Hot Water Circulation (HWC) and EHTF in bundle. A general presentation of these systems is given, including design, fabrication and installation methods, as well as the maturity of the technology. Typical field architecture is proposed to illustrate the benefits of each active heating technology in terms of field development optimisation.
This paper provides global information and an understanding of different available solutions for active heating pipeline systems, with technical and economic perspectives, and concludes with elements for selection of optimised field architecture.
Wet DEH is a field proven technology with large track record that has already been installed on a 43km pipeline in 1070m water depth. It fits production fields not requiring high thermal insulation performances and thus allowing wet insulated pipe (U-Value =2W/m2.K). The system presents high electrical power requirement (50-150W/m). Therefore, infrastructure capacities in terms of footprint and power supply available have to be checked against specific project power requirements.
EHTF fits production fields requiring high thermal insulation performance provided by Pipe-in-pipe (down to U-Value < 0.5W/m2.K). Thanks to its high efficiency, the system has low power requirement (typically below 50W/m). Therefore, it can also be an alternative to DEH when topsides capacities cannot meet footprint and power supply requirements. Pipeline heat tracing is a known technology for onshore plants and by extension applicable for subsea applications. The implementation of EHTF is completing qualification of this technology for deepwater applications.
HWC within bundle is a field proven technology. It fits production fields requiring high thermal insulation performance provided by bundle arrangement (down to U-Value < 0.5W/m2.K). The technology requires power and equipment to heat water thus impacting topsides space. These requirements vary considering project specific needs and selection of direct or indirect heating. For example, re-use of the produced water as an indirect heating medium can highly limit required power generation.