MULTIDIAMETER, BIDIRECTIONAL PIGGING （MULTIDIAMETER,双向清管）.pdf

MULTI-DIAMETER, BI-DIRECTIONAL PIGGING FOR PIPELINE PRE-COMMISSIONING By: Magne Andreas Vik, StatoilHydro; Alf Åge Kristiansen, StatoilHydro Simon Sykes, FTL Seals Technology; Steve Hutcheson, Pipeline Pigging Technology and Aidan O’Donoghue, Pipeline Research Limited. This paper examines the issues associated with multi-diameter, bi-directional pigging specifically for pipeline pre-commissioning. The technique can be used to flood and subsequently dewater a pipeline without the need for temporary subsea traps. An example is the Alve Pipeline in Norway. This 16 km flow-line from the Norne Platform to the Alve Manifold includes 10” and 12” pipe sections. The line was flooded from Norne using the pig with oxygen scavenged seawater and then dewatered using Nitrogen and produced gas from the well. The pigs needed to have a high sealing efficiency since very low velocities were used to flood the line and in order to avoid hydrates on dewatering. Multi-diameter wheel pigs were employed with non-buckling disc type seals. This paper describes the design of the pigs and the seals to achieve the required functionality. The test facility and testing performed to verify the pig performance is also illustrated. Finally, an overview of the offshore pigging operation is provided. Introduction In order to flood and subsequently dewater the Alve flow line, a number of high seal, multi-diameter and bi-directional pigs were required. The pipeline contains several internal diameters from 10” to 12”. Since no pigging from the Alve manifold was possible (no launcher), all operations needed to be performed from Norne FPSO. Four pigs spaced with MEG were launched from Norne with oxygen scavenged water, propelled through the pipel