SECTION 165:10-11-6. Plugging and plugging back procedures

(a)   Scope. This Section establishes minimum standards for plugging and plugging back wells. The standards apply to:

(1)   Wells drilled for the production of oil or gas.

(2)   Wells drilled or used for disposal or enhanced recovery injection.

(3)   Wells used in subsurface gas storage units.

(4)   Monitoring wells in enhanced recovery projects or subsurface gas storage units.

(5)   Wells plugged back for:

(A)   Oil or gas production.

(B)   Disposal or injection.

(C)   Conversion to a water well.

(6)   "Rat hole" or "mouse holes" used in rotary drilling of wells.

(7)   Wells used for geophysical or geological exploration.

(8)   Wells used for other service operations.

(b)   Alternate plugging materials and procedures.

(1)   The Manager of Field Operations, or other designated Conservation Division staff member, may approve the use of an alternate material other than cement or in combination with cement for wells listed in subsection (a), provided alternate plugging materials shall not be used to plug or plug back wells listed in subsection (a)(2), wells drilled or used for disposal or enhanced recovery injection, subsection (a)(3), wells used in subsurface gas storage units, subsection (a)(5)(B), wells plugged back for disposal or injection, and underground injection wells authorized under the Oklahoma Brine Development Act, 17 O.S. Section 500 et seq.

(2)   The Director of Oil and Gas Conservation, in consultation with the Conservation Division's Field Operations staff and the public, shall develop specific plugging criteria for any type of alternate plugging material authorized for use instead of cement or in combination with cement. The plugging criteria for approved alternate material shall be available to the public for review and copying at the Conservation Division's offices and on the Commission's Internet website.

(3)   A District Manager may approve alternate plugging procedures for the use of alternate plugging materials.

(4)   A detailed description of the alternate plugging operation shall be included with the Plugging Report (Form 1003).

(5)   The District Manager shall note his approval of the alternate plugging procedure on the well's Plugging Report (Form 1003).

(6)   Any alternate plugging material or procedure shall conform to the minimum plugging standards relating to formations or depths set forth in the Sections below. Provided, based upon the type of alternate plugging material being utilized, the District Manager approving the alternate procedure may authorize variances to the plugging standards delineated in this Section otherwise applicable to the use of cement, where such variances are necessary to ensure an effective well plugging.

(c)   Application and cross references:

(1)   Subsection (o) of this Section provides for administrative approval of alternative plugging procedures if downhole problems in a wellbore prevent an operator from complying with the minimum standards established by this Section.

(2)   Subsection (p) of this Section applies to plugging of "rat holes" and "mouse holes" used at the surface during rotary drilling.

(3)   OAC 165:10-11-8 establishes additional procedures for identification and control of wellbores in which certain logging tools have been abandoned.

(4)   OAC 165:10-7-31 establishes the minimum standards for plugging wellbores used in seismic exploration.

(5)   Subsections (d) through (q) of this Section establish plugging and plug back standards for all other wellbores subject to this Section.

(d)   Formations to be plugged.

(1)   Except as provided in (2) of this subsection, for cased formations, if the operator plugs or plugs back a well, the operator shall plug any formation or formations in communication with a formation that:

(A)   Bears H2S;

(B)   Bears oil or gas;

(C)   Bears treatable water;

(D)   Was used in the wellbore for injection as part of a saltwater disposal well or enhanced recovery injection well; or

(E)   Is open in the wellbore below either the shoe of the casing or the base of the liner to be left in the well after plugging.

(2)   Paragraph (1) of this subsection shall not apply to any formation behind the pipe left in the hole, unless a formation endangers a treatable water formation or any oil and gas bearing formation.

(e)   Mud requirements. Before or after running a plug, the operator shall remove or displace all oil and saltwater in the wellbore, and the operator shall fill the wellbore and/or casing with drilling (plug) mud. The minimum mud weight shall be nine pounds per gallon. The minimum viscosity for the drilling mud shall be 36 (API Full Funnel Method). If the operator removes casing from the wellbore, the operator shall keep the wellbore filled with drilling mud meeting or exceeding the weight and viscosity requirements of this subsection.

(f)   Cement requirements.

(1)   Quality of cement. All cement and/or alternative materials used in plugging wells shall meet or exceed the following specifications:

(A)   Minimum compressive strength: 500 psi;

(B)   Maximum Young's modulus: < 1.2 x 10 psi;

(C)   Permeability: < 0.1 mD; and

(D)   Minimum concentration of Portland cement: approximately 20%.

(2)   Required information.

(A)   The plugger shall provide quality control data sheets regarding the cement to the appropriate Conservation Division District Office, which data shall include, but not be limited to, the most recent laboratory test results for the cement. Laboratory test results for the cement must be no more than 12 months old.

(B)   If requested by a representative of the Conservation Division, a sample of the cement shall be split and an adequate portion (approximately one gallon) shall be properly labeled and delivered or otherwise provided to the appropriate Conservation Division District Office or Field Inspector.

(g)   Approved cementing methods.

(1)   Cement plugs.

(A)   To plug or plug back a well, either the tubing and pump method or the pump and plug method shall be used and a continuous flow of cement shall be pumped for each stage.

(B)   Surface pumping and shut in pressures shall be of sufficient pressure to:

(i)   Squeeze off perforations in the casing.

(ii)   Prevent the plug from floating upward in the wellbore.

(2)   Bridge plugs. The operator may run by the bailer method cement required in the casing above a bridge plug as provided by (g) of this Section.

(h)   Use of bridge plugs.

(1)   Permitted use. Except as provided in (2) of this subsection for top plugs, a bridge plug may be used to permanently plug off a formation if:

(A)   The only openings from the formation into the wellbore are perforations in the casing.

(B)   The annulus between the casing and the formation is filled with cement from a depth 50 feet below the base of the formation to a depth 50 feet above the top of the formation.

(C)   The bridge plug is set above the top of the perforations in the cemented interval described in (B) of this paragraph.

(D)   Sufficient cement is placed on top of the bridge plug to fill the casing from the top of the bridge plug to a depth ten feet above the top of the bridge plug.

(2)   Prohibited use for top plug. A bridge plug may not be used for a top plug described in (k) of this Section.

(i)   Cement plug for uncased hole below the casing or liner. If any production casing or liner is to be left in the wellbore, then any uncased hole below the casing or liner shall:

(1)   Be filled with cement:

(A)   From a depth which is the lesser of total depth of the well or 50 feet below the lower of shoe of the casing or base of the liner.

(B)   To a depth of 50 feet above the lower of the casing shoe or the base of the liner; or

(2)   Have a cast iron bridge plug set above the top of the liner with cement.

(j)   Intermediate cement plugs. If a bridge plug and cement are not used, a cement plug shall be run over any other formation required to be plugged off by this Section. To plug off a formation, the wellbore shall be filled with cement from a depth at least 50 feet below the base of the formation to a depth at least 50 feet above the top of the formation.

(k)   Cement top plug.

(1)   No treatable water exists. If no treatable water exists, the wellbore shall be filled with cement from a depth of at least 30 feet to a depth of three feet from the surface.

(2)   Treatable water exists. Except as provided in (q) of this Section for converting a well to a water well, the wellbore shall be filled with cement as follows:

(A)   If there is no surface casing or the base of the surface casing is 25 feet or further above the base of the treatable water, the wellbore shall be filled with cement from a depth of at least 50 feet below the base of the treatable water to a depth the lesser of:

(i)   Fifty feet above the base of treatable water; or

(ii)   Three feet below surface.

(B)   If the surface casing is set at or below the base of the treatable water, when requested in the plugging plan by the District Manager, the production casing shall be cut off a minimum of 50 feet below the base of the surface casing, the production casing must be removed from the wellbore and the wellbore shall be filled with cement from a depth of at least 50 feet below the base of the surface casing to a depth the lesser of:

(i)   Fifty feet above the base of the surface casing; or

(ii)   Three feet below surface.

(C)   If the cement plug prescribed by (2) of this subsection is not sufficient to bring the level of cement to within three feet from the surface, then the wellbore shall be filled with cement from a depth of at least 30 feet to a depth of three feet from the surface.

(l)   Cutting off surface pipe and identification of the abandoned wellbore.

(1)   This subsection applies to a wellbore plugged for abandonment. It does not apply to a wellbore plugged back for conversion to a water well under (q) of this Section.

(2)   After setting the top plugs in a well, the operator shall cut off the casing left in the wellbore three feet below surface, and the operator shall cap the casing in the wellbore with a steel plate.

(3)   The operator shall inscribe or embed the well number and date of plugging on the steel plate.

(m)   Tagging the top of the plug. The Field Inspector for the Conservation Division may require the operator to determine the depth of the top of a plug by running a wireline or tubing string.

(n)   Fall back of cement. If the cement for a plug falls back during setting below the top depth required by this Section, the operator shall run additional cement until the plug meets the minimum requirements of this Section.

(o)   Alternative plugging procedure for down-hole problems.

(1)   In plugging a well, if the operator encounters a downhole problem which prevents the operator from complying with the standards of this Section, the District Manager may prescribe an alternative plugging procedure provided that the alternative plugging procedure prevents the vertical migration in the wellbore of oil, gas, saltwater, H2S, and other deleterious substances into a formation bearing oil, gas, or treatable water.

(2)   The District Manager shall note his approval of the alternative plugging procedure on the well's Plugging Report (Form 1003).

(p)   Plugging of rat holes and mouse holes. If a rat hole or mouse hole was used at the surface for drilling the well, it shall be plugged within 90 days after drilling operations are complete as follows:

(1)   The hole shall be filled with drilling mud from bottom to a depth eight feet below the surface.

(2)   The operator shall fill the hole with cement from a depth of eight feet to a depth of three feet below the surface.

(3)   The operator shall fill the hole with dirt from a depth of three feet to surface.

(q)   Plug back for conversion to a water well. The District Manager may permit a well operator to plug back a well for permanent use as a water well by:

(1)   Setting any bottom hole and intermediate plugs required by this Section.

(2)   Setting a top cement plug from the base of treatable water to 50 feet below the base of treatable water.

(3)   Obtaining written permission from the owner of the ground water rights for conversion of the well to a water well.

(4)   Submitting under 165:10-11-7, a Plugging Report (Form 1003) noting the conversion of the well with a copy of the written permission from the owner of the ground water rights for conversion of the well to a water well.

(5)   A determination must be made by the Oklahoma Water Resources Board as to whether the well is to be permitted as a water well.

[Source: Amended at 13 Ok Reg 2395, eff 7-1-96; Amended at 14 Ok Reg 2198, eff 7-1-97; Amended at 15 Ok Reg 2989, eff 7-15-98; Amended at 16 Ok Reg 842, eff 1-5-99 (emergency); Amended at 16 Ok Reg 2190, eff 7-1-99; Amended at 19 Ok Reg 1947, eff 7-1-02; Amended at 27 Ok Reg 2128, eff 7-11-10; Amended at 28 Ok Reg 1949, eff 7-11-11; Amended at 34 Ok Reg 921, eff 9-11-17; Amended at 35 Ok Reg 973, eff 9-14-18; Amended at 36 Ok Reg 534, eff 8-1-19]