Design and Analysis of Electrically Heat-Traced Flowline EHTF Pipeline End Manifold PLEM Using Seven Vega

Abstract

Abstract This paper presents the successful design and installation of the EHTF (Electrically Heat Traced Flowline) PLEM (Pipeline End Manifold) using the newly built, highly capable pipelay vessel, Seven Vega. This was achieved by taking advantage of Seven Vega's reel lay firing line capabilities. The EHTF PLEM is an essential component of the EHTF system which combines the Thermal performance of PiP (Pipe in Pipe) flowline with Electrical heating capability. The EHTF PLEM is a complex structure which is designed to flow production fluid from well jumpers and from an extension flowline through a flowline jumper, as well as extends electrical heating functionality to the extension flowline. It has 3 hubs, 6 gate valves, and 8 electric flying leads, the piping header, and the termination of the electrical system all in one structure. The final design resulted in major reduction of overall length and weight. The creative design went through multiple iterations to achieve the desired results while the vessel was still being built. Seven Vega is designed to install rigid flowlines including pipe in pipe systems and electrical trace heating, in water depths up to 3000m. Most reel-lay vessels have small PMA (PLET Manipulator Assembly) systems in the firing line. However, Seven Vega's bigger envelope and weight accommodates both 1st and 2nd end. Avoiding the need for cross-haul reduces cost and adds flexibility in the schedule. The result was the overall reduction in weight of the PLEM, flexibility of schedule, and successful design of the recoverable EHTF PLEM within PMA capacity of Seven Vega. This paper showcases the advanced capabilities of the newly built Seven Vega and focuses on optimization and installation of the essential PLEM structure of EHTF technology.