Pipeline Ending Manifold (PLEM)/PLET

The subsea field development concept was first suggested in the early 1970’s by placing wellhead and production equipment on the seabed with some or all components encapsulated in a sealed chamber. The hydrocarbon produced will then flow from the well to a nearby processing facility, either on the land or on an existing offshore platform. This concept was the start of subsea engineering, and systems that have a well and associated equipment below the water surface are referred as subsea production system.

As the oil&gas field development move further away from existing subsea infrastructures, it become advantageous to consider a subsea tie-in of their export system with existing deepwater pipeline system offering spare transport capacity. This necessitates incorporating pipeline end manifolds (PLEM’s) at both pipeline ends to tie in the system. A PLEM is a subsea structure used to connect rigid pipeline with other subsea structure such as a manifold or a tree, through a jumper. It is also called a pipeline end termination (PLET), especially to serve as a support for one pipeline valve and one vertical connector.

Manifolds are used to simplify the subsea system, minimise the use of pipelines and risers and optimize the flow of fluid in the system. The manifold as shown in the picture is an arrangement of piping and/or valves designed to combine, distribute, control and often monitor fluid flow. The numerous types of manifolds range from a simple pipeline end manifold (PLEM/PLET) to large structures such as a subsea process system.

Source:
https://oilandgastechnologies.wordpress.com/2012/08/08/subsea-field-development-concept/
https://oilandgastechnologies.wordpress.com/2012/08/08/subsea-plem-and-plet/
https://oilandgastechnologies.wordpress.com/2012/08/08/subsea-manifolds/