1. (1) During the drilling and construction of a Class VI well, appropriate logs, surveys, and tests must be run to determine or verify the depth, thickness, porosity, permeability, and lithology of, and the salinity of formation fluids in, each relevant geologic formation to ensure conformance with the injection well construction requirements of Rule R644-9 and to establish accurate baseline data against which future measurements may be compared. The well operator must submit to the division a descriptive report prepared by a knowledgeable log analyst that includes an interpretation of the results of such logs and tests. At a minimum, such logs and tests must include:

   1. (a) Deviation checks during drilling when a wellbore is constructed by drilling a pilot hole that is enlarged by reaming or another method. Such checks must be at sufficiently frequent intervals to determine the location of the borehole and to ensure that diverging holes are not created during drilling, to prevent avenues for vertical fluid movement;

   2. (b) Before and upon installation of the surface casing:

      1. (i) Resistivity, spontaneous potential, and caliper logs before the casing is installed; and
      2. (ii) A cement bond and variable density log to evaluate cement quality radially, and a temperature log after the casing is set and cemented;

   3. (c) Before and upon installation of intermediate and long string casing:

      1. (i) Gamma ray, resistivity, spontaneous potential, porosity, caliper, fracture finder logs, and any other logs the division requires for the given geology before the casing is installed; and
      2. (ii) A cement bond and variable density log, and a temperature log after the casing is set and cemented;

   4. (d) A series of tests designed to demonstrate the internal and external mechanical integrity of injection wells, that may include:

      1. (i) A pressure test with liquid or gas;
      2. (ii) A tracer-type survey to detect fluid movement behind casing, such as a radioactive tracer, oxygen-activation logging, or similar tool;
      3. (iii) A temperature or noise log;
      4. (iv) A casing inspection log;
   5. (e) Any alternative methods that provide equivalent or better information and that are required and approved by the division.
2. (2) The operator must take whole cores or sidewall cores of each injection zone and confining system and formation fluid samples from each injection zone and must submit to the division a detailed report prepared by a log analyst that includes: well log analysis and associated well logs, core analysis, and formation fluid sample information. The division may accept information on cores from nearby wells if the operator can demonstrate that core retrieval is not possible and that such cores are representative of conditions at the well. The division may require the operator to core other formations in the borehole.
3. (3) The operator must record the fluid temperature, pH, conductivity, reservoir pressure, and static fluid level of each injection zone.

4. (4) At a minimum, the operator must determine or calculate the following information concerning each injection zone and confining zone:

   1. (a) Fracture pressure;
   2. (b) Other physical and chemical characteristics of each injection and confining zone; and
   3. (c) Physical and chemical characteristics of the formation fluids in each injection zone.

5. (5) Upon completion, but before operating, the operator must conduct the following tests to verify hydrogeologic characteristics of each injection zone:

   1. (a) A pressure fall-off test; and
   2. (b) A pump test; or
   3. (c) Injectivity tests.

6. (6) The operator must provide the division with the opportunity to witness all logging and testing described in this section. The operator must submit a schedule of such activities to the division 30 days prior to conducting each log and test.

   1. (a) The operator must notify the division at least 48 hours before conducting any wireline logs, well tests, or reservoir tests.

KEY: oil and gas law

Date of Last Change: July 31, 2025

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