Joint effort to reduce subsea incidents
Posted: 18 December 2006
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After more than a decade of fast-track subsea developments, the industry is now experiencing a need to consolidate its improved knowledge of subsea foundations. In addition, the current state of knowledge regarding the design and installation of offshore foundations in general must be compiled. "Therefore, DNV is now launching a joint industry project and invites the international oil and gas players to sign up to the development of a new 'handbook' for offshore foundations," explains Pål J. Str¸m, DNV's project manager.
Over the past few years, a number of costly incidents with time-consuming repairs have occurred during subsea installations. "Mostly, these incidents happened because of insufficient attention to installation issues in the foundation design process. Now, DNV, together with major oil and gas players, is going to establish recommended practices to ensure installations with a higher awareness of these issues," says Pål J. Str¸m.
One particular challenge involves landing suction pile foundations to support deepwater structures. Pål J. Str¸m explains; "Landing a foundation structure with a high centre of gravity combined with the need to rapidly evacuate the water inside the foundation during self-penetration may cause the foundation to tilt significantly. The result may be a lack of compliance with installation tolerances."
Another challenge involves drilling for wells in the vicinity of bucket foundations, where a lack of knowledge may result in the severe undermining of the soil supporting the structure.
This new DNV Recommended Practice, DNV-RP-C208 "Foundations", will be based on the current and widely used DNV Classification Note 30.4, with updates and amendments to reflect the current state of knowledge as well as the needs of the industry.
The following new topics will be considered for inclusion, in addition to those already covered:
- Design strategies for subsea installations
- From soil investigation to design soil parameters
- Design by FE analysis - requirements as to documentation and auditability
- Well integrity
- Fixity of jack-up foundations equipped with skirts
- Pipe capacity in very dense sand
"I'm confident that this joint industry project will produce valuable knowledge and practices which will reduce the number of incidents in the future," concludes Pål J. Str¸m, who urges interested parties to join this project. |
