The facilities regulations § 48

§ 48 Well barriers

Well barriers shall be designed such that well integrity is ensured, and the barrier functions are safeguarded during the well's lifetime.
Well barriers shall be designed such that unintended well influx and outflow to the external environment is prevented, and such that they do not hinder well activities.
When a production well is temporarily abandoned without a completion string, at least two qualified and independent barriers shall be present.
When a well is temporarily or permanently abandoned, the barriers shall be designed such that they consider well integrity for the longest period of time the well is expected to be abandoned.
When plugging wells, it shall be possible to cut the casings without harming the surroundings.
The well barriers shall be designed such that their performance can be verified.
Section last changed: 01 January 2014

The well’s life span as mentioned in the first subsection, means time in use and time subsequent to permanent plugging and abandonment.
In order to fulfil the requirement regarding well barriers, the NORSOK D-010 standard Chapters 5, 6, 10 and Annex C should be used in the area of health, working environment and safety. See also Section 5 of the Management Regulations and Section 8 of these regulations.
The requirements in the first subsection also entail that the barriers shall be designed so that unintended outflow of injected material is prevented.
The requirement as mentioned in the second subsection, means that it should be assessed whether to insert casings for drilling in zones which may contain hydrocarbons. Robust well design and the potential for regaining well control in the event of an uncontrolled blowout should be given special assessment.
Verification of the performance of well barriers as mentioned in the final subsection, can be based on pressure testing, testing of accessibility, response time and leakage rates, as well as observation of physical properties.
The requirement regarding sufficient independence among the barriers as mentioned in Section 5 of the Management Regulations, entails that well barriers shall be independent, without common well barrier elements, also when the barriers have a common outflow source. One of the barriers may be drilling and well fluids, see NORSOK D-010 Table C.1.
With regard to the requirement for dimensioning of binding agents, plugs and seals, particularly in relation to the reduction in strength that can arise over time, see Section 11.