The Petroleum Safety Authority Norway (PSA) has found a reduction in the number of wells temporarily plugged and abandoned on the Norwegian continental shelf (NCS) from 2020 to 2022.
Its updated overview of such wells shows that they have declined from 268 in 2020 to 227 in May 2022, and that plans call for 117 of this remainder to be permanently plugged and abandoned by 2030.
The wells are divided into various categories depending on their integrity, with associated colour coding (figure) in accordance with Offshore Norge’s guideline 117 and the classification specified by Norsok standard D-010 for temporarily plugged and abandoned wells.
Wells in the orange and red categories declined from 24 in 2020 to 17 in 2022.
Regulatory requirements
The regulations specify that a well must have at least two independent barriers. Its integrity is categorised red or orange when one of these barriers has ceased to function.
When a well is no longer to be used, it must be permanently plugged within a reasonable time to protect it against future leaks. If the operator has other plans for the well, such as reuse, it can be plugged and abandoned temporarily.
The regulations set strict requirements for preserving the integrity of a well during temporary abandonment.
Section 88 of the activities regulations imposes restrictions on how long various types of wells can be temporarily abandoned, and specifies requirements for monitoring.
Where subsea-completed well are concerned, their integrity must be monitored if the plan is to abandon them for more than 12 months.
Exploration wells must not be temporarily abandoned for more than two years.
In production wells, hydrocarbon-bearing zones must be plugged and abandoned permanently within three years unless they are continuously monitored.
These requirements apply to exploration and production wells commenced after 1 January 2014.
Unmonitored
The 2022 survey shows that 32 of the 227 remaining wells which have been temporarily plugged and abandoned lack continuous monitoring and exceed the maximum limits set for exploration and production wells of two and three years respectively.
A temporarily plugged and abandoned well without monitoring is a status where the primary and secondary barriers are not kept under continuous observation and routinely tested.
The 32 wells in this category include the following.
- Two platform wells have been temporarily plugged and abandoned for more than three years without continuous monitoring. One is categorised as orange, with a future activity plan still under evaluation.
- Five exploration wells have been temporarily plugged and abandoned for more than two years without continuous monitoring. All are categorised as green. Four were temporarily plugged and abandoned around 1990, with some work remaining before permanent plugging and abandonment can be completed.
- Twenty-five subsea wells have been temporarily plugged and abandoned for more than three years without continuous monitoring. Four were temporarily plugged before 1 January 2014 and are therefore not subject to the regulatory requirement for time limits/monitoring. The remaining 21 have exceeded the regulatory limit by three years. Twenty of these are on a field which has been off stream for a period because of upgrading.
- Red and orange wells
- One of the 25 subsea wells which have been temporarily plugged and abandoned for more than three years without continuous monitoring has been categorised as red, and three as orange.
- Diagnosis and repair of the red subsea production well without continuous monitoring is under way. It will be permanently plugged and abandoned in the near future.
- Two of the three unmonitored orange subsea wells have already been permanently plugged and abandoned, and the third will be reused.
Duties of the companies
- Responsibility for well integrity and safety rests with the companies. The PSA expects them to comply with the regulatory requirements and to ensure that they operate prudently.
- Where wells are categorised as red or orange, the companies must take action to comply with the regulations and re-establish well barriers as quickly as possible.
- The PSA follows up the companies closely to assure itself that temporarily abandoned wells are dealt with in a good and safe way.
