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DECOMMISSIONING INSIGHT REPORT
2016
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Subsea isolation valves
In relation to wells, these may be referred to as a subsurface safety valve
(SSSV). This is a safety device installed in the upper wellbore to provide
emergency isolation of the producing fluids in the event of an emergency.
Two types of subsea isolation valves are available: surface-controlled and
subsurface controlled. In each case, the safety valve system is designed
to be fail-safe, so that the wellbore is isolated in the event of any system
failure or damage to the surface production-control facilities. In subsea
facilities, isolation valves are included in the seabed manifold to isolate
wells and piping to protect facilities in the event of an emergency or
routine need to prevent fluid flow.
Subsea tie-back
Subsea tie-backs usually connect small reservoir accumulations, developed
using subsea trees and manifolds, back to a host platform for onward
processing and or transportation.
Trunkline
Trunklines are defined as pipelines with a diameter greater than 14 inches
and a length in excess of 18 kilometres.
Tubing
Usually referred to as production (or injection) tubing. This is a pipe
inserted in the well to carry and contain the production (or injection) from
the reservoir to the surface.
UKCS
UK Continental Shelf
Umbilical
Utility support pipes
Well-scale decontamination
The removal and decontamination of scale build-up that deposits in the
tubing of a well during production of reservoir fluids.
Well P&A
Well Plugging and Abandonment
Wellhead
The wellhead is the termination point where the casing strings in the well
are supported and provide pressure containment.
Wireline
A form of well intervention that uses an electrical cable to lower tools into
the borehole and to transmit data to the surface.
W o S
West of Shetland