The audit was carried out in the period 21 November to 6 December 2018.

The Valhall field is in the southern part of the Norwegian sector of the North Sea. Aker BP is the operator.

The field began production in 1982 and comprises a field centre with six platforms and two unmanned flank platforms.

Vallhall IP was originally a water injection facility, but today both production and injection wells are drilled from the facility. This has led to a change in risk picture and barrier management.

The drilling contractor for Valhall IP is Archer.

Background and objective

The objective of the audit was to monitor how Aker BP and Archer (the drilling contractor), together with the sub-contractors, are meeting the regulatory requirements for planning, risk assessment and execution of drilling and well operations, as well as following up the authorities’ and the companies’ own requirements for managing major accident risk.

This audit is part of a series of audits of operators, drilling contractors and service companies on the Norwegian Continental Shelf. Important rationales for the audits are incidents, experiences from prior audits and investigations, and whistleblowing concerning drilling and well activities in the petroleum industry.

Valhall IP entered service in 2002 and, over the years, more than 350 demanding wellbores have been drilled on the Valhall field. The complex geology overlying the discovery, with gas and low-permeable zones, along with the reduced (depleted) pressure in the oil reservoir, have made it difficult for the company to find an optimum well design.

During the audit of Aker BP, we placed particular emphasis on how decision support, criteria and processes, as well as risk assessments, are established and implemented in order to safeguard well integrity and ensure robust operations.


Our audit identified three regulatory non-conformities:

  • Deficient establishment of a barrier management system for Valhall that matches actual conditions on the facility.
  • Deficiencies in performance of functional testing of blow out preventer (BOP) and non-conformity in closing time of BOP shear ram.
  • Deficiencies in well control training and exercises.

We also observed four improvement points:

  • Lack of specific detailed measures in the event of planned weakness in the primary barrier during drilling into the reservoir.
  • Lack of well control procedures in the event of a major loss during drilling in the reservoir section.
  • Deficiencies in well design and well integrity.
  • Lack of documentation of BOP shear capacity on the drill floor.

What happens now?

We have asked Aker BP to report on how the non-conformities will be addressed. We have also asked the company for feedback that assesses the improvement points we observed.

The deadline for this is set at 1 March 2019.