An umbilical is a bundle of tubes and cables that
- provides hydraulic power to subsea control systems
- provides electric power and signal to subsea control systems
- delivers chemicals for subsea injection at the subsea christmas tree or downhole
- can provide bulk methanol
- can provide gas for gas lift
An electrohydraulic subsea control umbilical tyically supplies electrical power and multiplexed signal, hydraulics, and chemicals to one or more subsea control modules (SCMs) controlling subsea christmas trees and/or other elements of a subsea production system; and signals from subsea instrumentation back to the control centre.
A direct hydraulic control umbilical provides direct hydraulic control of each valve on a subsea christmas tree, through a bundle of tubes from the topsides hydraulic power unit (HPU) to the subsea tree. No electrical power or signal is required. Actuation of valves is by the supply of hydraulic power to the relevant tube. This is accomplished by opening the relevant valve on the manifold located on the topsided HPU. This type of umbilical is limited to subsea production systems with short offsets to the host and few trees. There is no further discussion of this type of umbilical in this article.
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