WHAT ARE RISER
This refers to a selection of tooling used 'on the deck' to move, assemble and run the riser system. Examples include internal and external riser lifting tools, connector make-up equipment and 'spiders'.
Riser handling tooling has become increasingly important of late – enabling significant deployment time savings and operational safety improvements through increasingly sophisticated hydraulics.
Claxton has developed an in-house suite of hydraulic running tools – available for sale or to rent – to enable safe and efficient running of riser system.
One example of this focus in action are our optimised flanges and bolt torqueing equipment. We supply a variety of optimised flanged connections – complimented by bespoke make-up equipment that tensions all bolts simultaneously. This has significantly reduced the running time of each riser joint.
WHAT IS A
A drilling riser is a conduit from a subsea well to the surface, used in offshore drilling operations that acts to provide three critical functions:
Risers are used both subsea and surface in a variety of configurations to suit the needs of a drilling operation. Subsea risers are used in both jack up and semi-submersible drilling operations, however their design and configuration is quite different between the two modes of drilling – dependant on a variety of factors including; depth, current strength, wave frequency and height.
In all instances the riser must satisfy a number of critical operating criteria – the wellbore fluid (and pressure) must be contained and the riser itself must withstand any environmental loading.
Claxton has been providing complete surface and subsea risers to jack up rigs around the world since the early 1990's and supplies complete systems for sale or rental, up to 12,200 psi.
Discover more about our riser systems capability...
Riser tensioning refers to the practise of 'pulling tension' on a riser string to overcome the adverse effects of environmental loading on the riser, support the riser itself (if free standing or not supported by guides) and minimise the effect of heavy surface well-control equipment stack-up on top of the riser.
Tension systems usually comprise of a hydraulic power unit, connected to a tension system (an array of hydraulic cylinders to provide the required force), interfacing with the drilling riser via a tension ring, an integral load shoulder or a rack located on the riser's top or tension joint.
As operational demands of jack up rigs continue to grow in order to operate in deeper water and more severe environmental conditions, the expectations of tension systems have expanded to suit - with 400 and 500Te tension systems capacities becoming commonplace.
Claxton has long been a pioneer in tensioning – inventing the first-ever positive-grip riser tension ring and continually pushing the upper-limit of riser tensioning technology.
Learn more about our tensioning equipmen:
WHAT IS VORTEX
Vortex induced vibration (VIV) is caused by currents acting on the riser system – areas of low pressure can be created as a current flows over the riser and this can cause the riser to move or vibrate.
This vibration may not be uniform at different heights the riser stack will be subject to different environmental loading. Additionally if the frequency of VIV 'locks on' to the natural resonance of the riser material, VIV damage can be catastrophic.
Ultimately VIV reduces fatigue life performance and, in extreme cases, can damage costly riser and well-control equipment.
Riser analysis is critical in establishing the need for, and extent of, any VIV suppression on your riser system.
Claxton supplies VIV suppression from simple 'strakes' to fairings with swivel around the riser dynamically in relation to currents.
Full bore 18.3/4" riser systems in 5000, 7000 and 12000 psi pressure ratings.
Slim bore 14.3" riser systems, 6500 psi, for use with 13.5/8" stacks.
LP and HP surface risers with a range of ID's
An unrivalled selection of pressure, connection, tensioning and system tooling options for complete jack up drilling riser systems.
We supply full bore drilling risers up to 12,200psi – and have tackled some of the deepest waters ever drilled from a jack up rig.
Pictured: a riser we supplied to drill in 132m meters of water, offshore Norway.
Since we created the world's first fully adjustable positive-grip riser tension ring – eliminating time consuming space-out issues for our clients – Claxton has lead the way in riser tension rings and systems.