| Popis: |
Active heating technologies are for the moment based on topsides power distribution, limiting by default, the length of the flowline that can be heated. It is proposed to extend the range of active heating technologies by utilizing a field architecture that enables production for very long tie-backs by combining subsea electrical power distribution with the most efficient active heating technology the "Electrically Heat Traced Flowline" (EHTF) technology. The paper will present typical field architectures that require such combinations of subsea electrical power distribution and efficient active heating technology, typically brown fields with remote tie-backs that could not be developed with available technologies. EHTF Technology is based on a field proven high performance thermally insulated pipe-in-pipe, limiting the heat loss. Multiple high voltage wires, connected as three phase circuits, laid under the insulation along the entire length of the fluid carrier pipe, are used to provide heating. The heating wires extend typically 20km each side of a small in-line structure allowing safe penetrations into the pipe-in- pipe annulus. This small structure is powered on by a power cable, laid alongside the flowline, via a subsea electrical power distribution unit, which can be combined with a subsea transformer, to distribute the power to the multiple heating circuits within the annulus. Exceptional thermal efficiency of the insulation system generates lower heating power requirements, meaning that subsea distribution systems can be designed with reliable and off the shelf components, easily retrievable and maintained with low operational expenditures. Multiple circuits in the cross-section offer a greater operational flexibility and improved reliability of the system. Different power outputs can be provided from simple switching control depending on the heating requirement. Combining an efficient, reliable and flexible active heating technology with a simple and robust subsea power distribution allows development of remote fields that can be tied-back to existing facilities, virtually without limitation in length. |
