Drilling risers extend from the blow-out protector (BOP) on the seabed to the drilling vessel providing fluid communications between the well and the vessel. The riser supports the ‘choke’, ‘kill’ and auxiliary lines while also being used to guide tools into the well.
The weight of drilling risers can be enormous and this generates high levels of strain and tension on the host vessel. MDRB serves many functions including the reduction of the submerged riser weight and the provision of ‘lift’.
The lift effect is transferred to the riser by a thrust collar fitted to the riser pipe below the upper coupling. A matching collar is normally installed at the lower end of the assembly to facilitate the transfer of the module weight during handling.
MDRB technical information
External coating MDRB operates in extreme conditions and must withstand harsh and constant handling. Durafloat modules incorporate glass reinforced fibres to deliver a robust, impact-resistant performance.
Colour coding The international drilling community uses a colour system for quick identification of differing depth rated modules which is shown here:
Typical colour coding standards
Attachment methods Kevlar strapping with stainless steel axis bars and stud bolts is the standard system used to attach MDRB modules to the riser. Other options are available including through bolts or stainless steel U-bolts with enclosed Kevlar strapping.
Module stability 300mm flats are standard across the Durafloat range. This allows safe and effective stacking in the yard or in an offshore environment.
Flexural pads These are built into MDRB modules at strategic locations to ensure that excessive bending loads are not transferred from the riser to the module when lifted in the horizontal plane.
Ancillary hardware and services
Thrust collars Fitted to the riser at either end of the buoyancy string to transfer the loads generated by buoyancy uplift while submerged and to offset the weight transfer during retrieval operations.
Repair service We offer a comprehensive repair service to damaged buoyancy modules, including: • Repair of full breaks
• Rebuild of missing sections
• External reinforcement
• Void filling
