§ 50 Compensator and disconnection systems
Floating facilities shall be equipped with a disconnection system that secures the well and disengages the riser before a critical angle occurs.
When designing the compensator system, robust technical solutions shall be chosen where faults do not result in unacceptable consequences, cf. Section 5 litera c.
Section last changed: 01 January 2011
To fulfil the requirement for compensator and disconnection systems as mentioned in the first and second subsections, the NORSOK D-001 standard Chapters 5 and 6 should be used, with the following additions:
- For anchored drilling facilities it should be possible to move quickly off the drilling location in case of a critical situation,
- For interventions on seabed wells with high pressure risers, the valve and disconnection system should consist of
- a remote-operated valve located under the release point, which cuts all objects that penetrate the well barriers and maintains full working pressure after cutting,
- a remote-operated main valve that closes after the cutting is completed,
- a block valve over the release point which prevents blowout from the riser to the sea,
- a vent valve that releases shut-in pressure between the casing ram and the shear ram or block valve prior to release.
For requirements relating to specific analyses to detect accident and hazard situations, reference is made to Section 17 of the Management Regulations. For general requirements related to dimensioning of compensator and disconnection systems as regards loads, see Section 11. The following should be taken into account when stipulating limitations for drilling equipment:
- Movements of the facility as a result of resonance between the wave frequency and the frequency of the facility itself,
- Movement of the facility as a result of loss of position because of anchor line breakage or drift,
- Loads on well and wellhead from pull in riser,
- Margin due to uncertainty in calculated riser design,
- Risk of unintended locking of compensator with ensuing tensile stresses exceeding the dimensioning loads/effects that can occur in the course of well testing and well intervention.
For mobile facilities that are registered in a national ship register, DNV-OS-E101 Chapter 2, Section 5, Paragraph 4 may be used as an alternative.