14. Decommissioning boreholes
What you must comply with when decommissioning boreholes at oil and gas sites.
You must comply with these regulations when closing a well:
- Borehole Sites and Operations Regulations 1995
- well aspect requirements of the Offshore Installations and Wells (Design and Construction) Regulations 1996
- Petroleum Exploration and Development Licence
You must also comply with the Guidelines for Decommissioning of Wells produced by the well decommissioning working group of the Oil and Gas UK wells forum. These guidelines include the requirements to:
- seal any permeable layers within the well
- fill the remainder of the well with cement between 2 cement plugs – locate the lower plug at a level that will prevent material from the well moving into the surrounding strata
- remove the wellhead and cut and seal the casings below ground level
The closed well will need to be reviewed by an independent well examiner and the HSE before the site can be reinstated back to its pre-operative state.