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Interim Directive ID 81-01

TO: ALL OIL AND GAS OPERATORS

SUBSURFACE DISPOSAL OF DRILLING FLUIDS

This Interim Directive supersedes Interim Directive ID 70-3 issued on 15 December 1970.

The Board will permit operators to dispose of drilling fluids not only in dry holes, but to any well where subsurface disposal of drilling fluids is feasible.

The Board believes that under appropriate constraints the subsurface disposal of drilling fluids can be carried out without jeopardizing any subsurface potable water horizons. It will consider such disposal as part of the drilling or completion program for a well and separate approval under section 38 of The Oil and Gas Conservation Act will not be required. The subsurface disposal of drilling fluids may be carried out subject to the following conditions:

1. Permission of a Board representative shall be obtained before any disposal operation is commenced.
   
   
2. The disposal zone shall be at a depth not less than 600 metres.
   
   
3. The resistivity directly attributable to the total natural dissolved solids in the FORMATION WATER of the disposal zone shall be less than 0.33 OHM.M corrected to 20C (equivalent to 20 000 ppm total dissolved solids).
   
   
4. The disposal zone shall be known not to contain hydrocarbons within 2 kilometres of the intended disposal well.
   
   
5. Where a well is to be abandoned or plugged back, and does not contain at least 600 metres of casing cemented in place:
   

   (a) the disposal of fluids shall be through drill pipe and below a seated packer, and
   
   (b) the annulus between the drill pipe and the surface casing shall remain open to the atmosphere during any disposal operation.
   

6. Where a second casing string has been run in a well and not cemented to surface:
   

   (a) the disposal of fluids shall be through the annulus between the casings, provided the surface casing is deeper than 600 metres,
   
   (b) the disposal zone shall be identified by depth and geological designation,
   
   (c) the fluids to be disposed shall be displaced out of the annulus with a corrosion inhibited fluid. If, after displacement, pressure exists in the annulus, cement shall be displaced into the formation to seal off the disposal interval, and
   
   (d) the annulus shall be left open to the atmosphere in the manner described in subsection 6.100(2) of the Oil and Gas Conservation Regulations.

7. Where the disposal zone has been cemented behind casing:
   

   (a) the disposal zone shall be identified by depth and geological designation,
   
   (b) the casing shall be perforated and the fluids disposed of through the perforations, and
   
   (c) the perforations shall be appropriately sealed or isolated.

ISSUED at Calgary, Alberta, on 12 March 1981.

ENERGY RESOURCES CONSERVATION BOARD

[signed by]

V. E. Bohme
Board Member