Survey - Offshore engineering and construction
For more about hydrographic survey operation click here. For
pictures of platforms
and other offshore installations click here.
An example of part of the development of one field, Tyrihans, click here.
In addition to performing surveys and seabed investigations offshore
survey (or more correctly ROV support) vessels perform a wide variety
of construction and engineering related tasks. Some examples of these
activities can be found on this page.
Wellservicer at CCB offshore base outside Bergen
Often other vessels are invloved, whether it be anchor handlers, supply
vessels or DSVs (Diving Support Vessels). Often special
tooling must be mounted on the ROV in order to perform such
Some recent developments such as Snøhvit and Ormen
have no surface platforms in place, with all structures based subseas.
These structures are operated either from shore or by support vessels
equipped with ROVs.
Draugen Loading Buoy
The Draugen Loading buoy is used by tankers to fill up with cargo, to
do this they must connect to a hose. The rigging on this hose required
repair so our task on this occasion was to use the ROV to hook up a
wire so the supply vessel "Ocean Sky" could pull the hose up and make
repairs to the rigging.
Amazingly a Long-tailed Duck continued to feed around the leg of the
loading buoy - apparently unconcerned by the activities of two vessels
working in close proximity to it.
pulling the hose from the loading buoy on deck
Langeled RFO work at Sleipner
As part of the preparations for the supply of gas to the UK from the
Ormen Lange field via the so-called Langeled pipeline various "pigging"
and flooding work had to be done. Here our vessel worked in conjunction
with the DSV Acergy Osprey - a Dive Support vessel I worked on briefly
in the 1990s.
Here the Acergy Osprey is seen working beside the Sleipner platform.
Acergy Osprey at Sleipner, February 2007
Acergy Osprey at Sleipner, February 2007
Concrete mattresses are often used to protect subsea installations,
Dawn (03:30!!) over the Acergy Piper, Tyrihans, June 2007
There are various types of pipelay vessel - some operate in "DP" using
thrusters and propellors to keep themselves in position. Others use
anchors - and during such a pipelay there can be an amazing number of
vessels involved. The barge itself, anchor handling vessels, pipe
carriers (to re-supply the barge) and lay support vessels.
Counteracts such as depicted above are used to physically constrain the
position of the pipeline during the lay. They are usually recovered
Initiation piles are used to anchor the pipeline when commencing a
pipelay. These piles need to be driven into
the seabed. Below is a picture of a piling hammer being recovered on
completion of such an operation.
Construction Vessel / Ice-breaker Botnica
Construction vessel S7000 near Stavanger, spring 2010
Construction vessel S7000 at Valhall, summer 2010
After a pipeline is laid and before it is hooked up and put into
production it must be checked and tested. This will often mean that the
pipeline is flooded, "pigged" and pressured up. "Pigs" are run through
the pipeline to perform various checks before pressure testing to
ensure there are no leaks. This task will be performed using an
offshore support vessel and requires a fair bit of deck space.
Bleeding off a pipeline after pressure testing.
Rock Dumping (or Rock installation)
An integral part of many
offshore construction operations
rock dumping, Rocks, gravel and sand is used for various reasons both
prior to and following the installation of structures such as templates
or pipelines. Rock berms can provide a stable and level surface on
which to deploy something, support a pipeline where it would otherwise
be in freespan or provide protection from other activities such as
Dredging and trenching
The FFPV (Flexible Fall Pipe Vessel) Tertnes is one of a number of rock
Rock dumping vessel Simon Stevin working off Kollsnes, Øygarden
it is necessary to uncover structures or pipelines buried under rock
dumps, or it may be necessary to dig a trench. There are many ways of
doing this but one of the more ingenious is pictured below. Operators
use a virtual seabed to dig in so a DTM of the area is a prerequisite
for this kind of work - often updated at regular intervals as work
All content on this site, including
the Natural Born Birder logo, is copyright © 2005-2015
High resolution versions of most
images on this website are available.
Please contact me for further
details or other enquiries