Client: Confidential
Location: Barents Sea

The objective of the study was to assess the risk related to operation of the gas lifted oil producers in a Barents Sea subsea oil field. Two well designs were assessed.


One well design included an annulus safety valve (ASV) in the completion string and one well design did not include an ASV. Otherwise the well designs were identical.

The detailed objective of the study was to compare the two well designs, including a discussion on risk reducing measures which can change the relative ranking between the concepts from a total risk level viewpoint.


The study primarily addressed uncontrolled leakage of gas lift gas and blowout from the reservoir to the sea during the production phase. Blowouts during drilling, completion and workover in a specific well were not included. Drilling, completion, and workover operations were, however, included as a potential dropped objects source.

Subcontractors carried out separate analyses related to consequences of gas released at the seafloor and specific analysis related to blowout rates through a failed gas lift valve.


The study resulted in specific risk-based recommendations that should be used as input for well design and well operation.