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Norwegian offshore safety agency rejects life extension for BP North Sea platform

22 December 2014

The Petroleum Safety Authority Norway (PSA) has turned down an application from BP Norge AS for consent to extend the operating life of the Quarters Platform (QP) on the Valhall field.
Valhall QP started its operational life in 1980, and, according to Valhall's Plan for Development and Operation (PDO), the design life of this installation was 20 years.

Valhall QP is the furthest platform from the camera - Image: Shutterstock
Valhall QP is the furthest platform from the camera - Image: Shutterstock

Extensions had hitherto been granted until the end of 2014, and the platform had been cleared to house 177 staff over the 2013/4 winter season. BP applied to the PSA for consent to extend the platform’s use until 31 December 2017.

This has been rejected because many years of oil and gas production have resulted in the Valhall reservoir becoming compressed, and the seabed has subsequently subsided. This subsidence means that the base of the topside on Valhall QP is nearer the sea surface than before, and no longer satisfies air gap requirements.

The PSA deemed that Valhall QP failed to meet the requirements for surviving a 100-year wave in occupied condition. BP accordingly had procedures in place for demanning when high waves were forecast, including a shut down from 20 December to 15 February to avoid those weeks of the year with the greatest probability of high waves, but this was not considered sufficient.

The PSA’s decision is as follows:

“BP is denied consent for continued operation of Valhall QP as an accommodation facility.

"In its analyses, BP has failed to define realistic acceptance criteria for non-linear analyses. The PSA considers that BP has underestimated the wave crest heights and the loads from steep waves. When determining demanning criteria, BP has failed to take account of higher-order waves and area effects. The PSA cannot therefore see that the company has fulfilled the requirements for analyses and for taking account of new knowledge and uncertainty, as specified in sections 16 and 17 of the management regulations on general requirements for analyses and on risk analyses and emergency preparedness assessments respectively.

“Based on the information provided by BP, the PSA cannot see that Valhall meets an acceptable level of safety which finds expression in the requirements for load-bearing structures as specified in section 56 of the facilities regulations on load-bearing structures and maritime systems, with guidelines, see also section 11 on load/actions, load/action effects and resistance, with guidelines.”

BP has yet to comment on what effect, if any, this decision will have on the field’s production capacity.

The Valhall field main production facilities include the original five bridge-connected platforms, including QP, and a new Production & Hotel (PH) Facility which has been operational since January 2013 and has accommodation for 180. This is designed to give Valhall a further 40-year design life with the capacity to handle 120,000bbl of oil and 143mcf of gas per day. The redevelopment project was designed to extend production from the field to 2050.

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