Subsea tree (wet trees) is a system of valves, flow paths, piping, and connectors installed on a subsea wellhead to contain and control the flow of fluid from a reservoir or from the surface by injection. ... Two type of subsea Christmas tree are vertical Christmas trees and horizontal Christmas trees.

What is the primary purpose of a subsea Christmas tree?

In petroleum and natural gas extraction, a Christmas tree, or "tree", is an assembly of valves, casing spools, and fittings used to regulate the flow of pipes in an oil well, gas well, water injection well, water disposal well, gas injection well, condensate well and other types of wells.

Why is it called a subsea Christmas tree?

Subsea and surface trees are an assembly of valves stacked on top of each other, with various spools, pressure gauges and chokes around the valves to control production and flow. The various pieces of equipment decorated around the arrangement of valves gave rise to trees being compared to Christmas trees.