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Subsea wells are essentially the same as dry completion
wells. However, mechanically they are placed in a Subsea
structure (template) that allows the wells to be drilled and serviced
remotely from the surface, and protects from damage e.g. from
trawlers. The wellhead is placed in a slot in the template where it
mates to the outgoing pipeline as well as hydraulic and electric
control signals.

Figure 5.5 – Subsea wells

Control is from the surface where a hydraulic power unit
(HPU) provides hydraulic power to the subsea installation via an
umbilical. The umbilical is a composite cable containing tension
wires, hydraulic pipes, electrical power and control and
communication signals. A control pod with inert gas and/or oil
protection contains control electronics, and operates most
equipment Subsea via hydraulic switches. More complex Subsea
solutions may contain subsea separation/stabilization and electrical
multiphase pumping. This may be necessary if reservoir pressure

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