1. (1) General. Each phase of Class VI well and Class VI Geophysical test well construction shall be supervised by a person knowledgeable and experienced in practical drilling engineering and familiar with the special conditions and requirements of injection well construction. Any materials and equipment used in the construction of the well and related appurtenances shall be designed and manufactured to meet or exceed the operating requirements of the specific project, including flow induced vibrations. Any well permitted as a Class VI Geophysical test well will need to meet the requirements of this rule before it can be permitted for use as a Class VI well. The operator must ensure that each well is constructed and completed to:

   1. (a) Prevent the movement of fluids into or between USDWs or into any unauthorized zone;
   2. (b) Allow the use of appropriate testing devices and workover tools; and
   3. (c) Allow for continuous monitoring of the annulus space between the injection tubing and long string casing.

2. (2) Casing and Cementing of Class VI Wells

   1. (a) Casing, cement, and other materials used in the construction of each Class VI well must have sufficient structural strength and be designed for the life of the geologic sequestration project. All well materials must be compatible with fluids that the materials may be expected to come into contact with and must meet or exceed standards developed for such materials by the American Petroleum Institute, ASTM International, or comparable standards acceptable to the division. The casing and cementing program must be designed to prevent the movement of fluids into or between USDWs. In order to allow the division to evaluate casing and cementing requirements, the operator must provide the following information:

      1. (i) Depth to each injection zone;
      2. (ii) Injection pressure, external pressure, internal pressure, and axial loading;
      3. (iii) Hole size;
      4. (iv) Size and grade of each casing string, including wall thickness, external diameter, nominal weight, length, joint specification, and construction material;
      5. (v) Corrosiveness of the carbon dioxide stream and formation fluids;
      6. (vi) Down-hole temperatures;
      7. (vii) Lithology of each injection zone and confining zone;
      8. (viii) Type or grade of cement and cement additives; and
      9. (ix) Quantity, chemical composition, and temperature of the carbon dioxide stream.
   2. (b) Surface casing must extend through the base of the lowermost USDW and be cemented to the surface through the use of a single or multiple strings of casing and cement.
   3. (c) At least one long string casing, using a sufficient number of centralizers, must extend to the injection zone and must be cemented by circulating cement to the surface in one or more stages.

   4. (d) Circulation of cement may be accomplished by staging. The division may approve an alternative method of cementing in cases where the cement cannot be recirculated to the surface, provided the operator can demonstrate by using logs that the cement does not allow fluid movement behind the wellbore. A copy of the cementing company's job summary or cementing tickets indicating returns to the surface shall be submitted as part of the pre-operating requirements.

      1. (i) If cement returns are lost during cementing, the operator shall have the burden of demonstrating, using wireline logs, that sufficient cement isolation is present to prevent the movement of fluid behind the well casing.
      2. (ii) If adequate cement isolation of the USDW or the injection zone within the casing-formation annulus cannot be demonstrated, remedial cementing shall be performed prior to proceeding with further well construction, completion, or conversion.
3. (3) Cement and cement additives must be compatible with the carbon dioxide stream and formation fluids and of sufficient quality and quantity to maintain integrity over the design life of the geologic sequestration project. The integrity and location of the cement shall be verified using technology capable of evaluating cement quality radially and identifying the location of channels to ensure that USDWs are not endangered.

4. (4) Tubing and Packer

   1. (a) Tubing and packer materials used in the construction of each Class VI well must be compatible with fluids that the materials may be expected to come into contact with and must meet or exceed standards developed for such materials by the American Petroleum Institute, ASTM International, or comparable standards acceptable to the division.
   2. (b) Injection into a Class VI well must be through tubing with a packer set within an interval of cemented casing, at a distance no more than 100' from the top of the approved injection interval, at a depth approved by the division. Any exception to the packer depth requirement must be approved by the division.

   3. (c) In order for the division to determine and specify requirements for tubing and packer, the operator must submit the following information:

      1. (i) Depth of setting;
      2. (ii) Characteristics of the carbon dioxide stream, such as chemical content, corrosiveness, temperature, and density, and formation fluids;
      3. (iii) Maximum proposed injection pressure;
      4. (iv) Maximum proposed annular pressure;
      5. (v) Proposed intermittent or continuous injection rate, volume, and mass of the carbon dioxide stream;
      6. (vi) Size of tubing and casing;
      7. (vii) Tubing tensile, burst, and collapse strengths; and
      8. (viii) Tubing manufacturer roughness factor.

KEY: oil and gas law

Date of Last Change: July 31, 2025

Authorizing, and Implemented or Interpreted Law: 40-11-3