P&A of Valhall DP wells

Abstract

The original platforms on the Valhall field will have to be decommissioned due to integrity issues. The oldest drilling platform, Valhall DP, has 30 wells that must be P&A in order to remove the platform. This thesis examines the challenges for P&A of the Valhall DP wells. To understand why the Valhall DP wells have to be P&A-ed, a detailed field description has been given, especially with regard to compaction and subsidence. Both internal BP regulations and NCS regulations have been evaluated and compared. Alaskan regulations have been compared as well to show the differences between different regulatory regimes. In order to P&A the Valhall DP wells according to NCS and BP regulations, new technology will have to be invented. A review of new technology, non commercialized technology and new plugging materials has therefore been included. A proposal for a general P&A plan has also been included.