Part 11. Well plugging

Where other publications are referenced within this Part, the reference shall be read as a reference to the most current edition of the publication in effect, including all published amendments.

11.01 Every person who plugs a well shall do so in a manner that:

  1. ensures the protection of potential oil or gas producing horizons;
  2. prevents the migration of oil, gas or water from one horizon to another;
  3. seals off and isolates all porous formations from those located above and below; and
  4. does not constitute a hazard to users of the surface.

Note: Refer to section 13 for well plugging reporting requirements.

11.1 Hydrocarbon storage and solution mining wells

  1. Plugging of hydrocarbon storage wells shall be in accordance with CSA Z341, Storage of Hydrocarbons in Underground Formations.
  2. Solution mining wells shall be plugged in accordance with the requirements of Section 9.9.

11.2 Removal of well casing and equipment

Casing, tubing and foreign material shall be removed from the well sufficiently to conform to the requirements of this Part.

11.3 Plugging materials

  1. Cement plugs shall be:
    1. neat cement without the addition of volume extender additives, gravel or any non-drillable material,
    2. mixed in accordance with API Spec 10A Specification for Cements and Materials for Well Cementing,
    3. in the form of a water-base slurry, having a weight of 1.9 kg per litre, and
    4. sulphate resistant where intended to isolate sulphur-bearing fluid zones.
  2. Bridges shall be of wood or stone, gravel, lead, or any combination of these or a special bridging device, but shall not include any non-drillable material.

11.4 Method of plug placement

Cement shall be deposited by displacement through tubing or drill pipe or by dump bailer.

11.5 Plug volume

  1. Pumped cement plugs, except the top plug, shall have sufficient slurry volume to fill 30 metres of hole plus 10% excess.
  2. Dump-bailed plugs shall have sufficient volume to fill 8 metres of hole plus 10% excess.

11.6 Locating plugs

The operator shall locate (tag) and provide for an Examiner to certify the placement and location of:

  1. each plug set at the top of each oil or gas fluid bearing zone, storage zone or salt cavern roof; and
  2. the top most plug set in the well.

11.7 Plug interval material

The intervals between plugs shall be filled with water or drilling mud.

11.8 Location of cement plugs

Regardless of whether casing is cemented in the hole the operator shall set cement plugs:

  1. above and below each oil, gas and fluid bearing zone and
  2. at the top of the Cambrian, Trenton, Cataract, Guelph, Salina, Dundee and bedrock formations, and at the base of the Guelph formation.

11.9 Size of plugs

Cement plugs shall extend a distance of 8 metres in the well.

11.10 Recovery of casing

The operator shall ensure that procedures for the recovery of casing comply with the following:

  1. surface casing, or other casing one size smaller in lieu thereof, may be recovered and where surface casing is left in the hole, it shall be fitted with a welded cap, or plugged with at least 3 metres of cement, and in all cases shall be cut off 1 metre below grade, except where the well is in a water-covered area, then the surface casing shall be cut off at or below the bed of the body of water;
  2. where surface casing is removed, the hole shall be filled completely to the surface with clay or sand or cuttings as the surface casing is withdrawn, except that a cement plug shall be set between 1 metre and 2 metres from surface; and
  3. when insufficient surface casing is set to protect every zone which contains potable water, and any such stratum is exposed to the well bore when production or intermediate casing is recovered from the well, a cement plug shall be placed across the interval from 15 metres below the base of the zone to 15 metres above the top of the zone.

11.11 Additional plugs

Additional cement plugs shall be set as follows:

  1. across the shoe of the surface casing extending at least 8 metres above and below the shoe:
  2. if surface casing has been set deeper than 60 metres below the base of the deepest potable water zone, an additional cement plug shall be placed inside the surface casing across the base of the deepest potable water zone;
  3. for wells in which the intermediate casing has been cemented across every porous zone intersected, a cement plug shall be placed inside the casing immediately below the base of the deepest potable water zone;
  4. if intermediate casing is to be left in the hole, a plug must be set across the shoe extending at least 8 metres above and below the shoe;
  5. for wells in which intermediate casing is not cemented through every porous zone, the casing shall be recovered to allow optimum placement of cement plugs;
  6. for wells in which the production casing has been cemented through every porous zone, a cement plug shall be placed inside the casing and immediately below the base of the deepest potable water zone and across any multi-stage cementing tool;
  7. for wells in which the production casing has not been cemented through every porous zone, the production casing shall be recovered to allow optimum placement of cement plugs at the required depths specified above;
  8. for horizontal drain hole wells the productive zone isolation plug shall be 8 metres and set at the top of the productive zone, or across the shoe of the production casing.

11.12 Bridge plugs

The operator may run a bridge plug above each perforated interval, if at least 8 metres of cement is placed on top of each bridge plug.

11.13 Well site rehabilitation – onshore

The operator shall return the well site to its original condition as nearly as practical and as soon as practical but no later than 6 months from the plugging date and the operator shall provide for an Examiner to visit the site and certify that rehabilitation and plugging of the well was completed in accordance with this Standard. Rehabilitation shall include:

  1. disposing of all liquid and solid waste in environmentally acceptable and safe manner;
  2. clearing the area of all debris;
  3. draining and filling the excavations;
  4. removing all surface works, unused concrete bases, machinery, and materials; and
  5. leveling and restoring original grade of the site.

11.13.1 Well site rehabilitation - water covered areas

When a well located in a water covered area is plugged, the operator shall cut off any casing left in the well at or below the bed of the body of water.

11.14 Reporting

The operator shall record the cement type, slurry weights, slurry volume, and special additive concentrations on the daily drilling report and submit a Form 10 report as required in Part 13 for every well plugged.