Multi-diameter, bi-directional pigging for pipeline pre-commissioning

摘要

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 Nome 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.