Current through Register Vol. XLI, No. 50, December 13, 2024
Section 35-3-5 - Casing Requirements - Coalbed Methane Wells5.1. Fresh Water Casing - For each coalbed methane well, the operator shall run and permanently cement a string of casing through the fresh water bearing strata. The fresh water protective casing shall extend at least thirty (30) feet below the deepest fresh water horizon (that being the deepest horizon which will replenish itself and from which fresh water or usable water for household, domestic, industrial, agricultural, or public use may be economically and feasibly recovered) and shall have cement circulated in the annular space outside the casing. The volume of cement needed shall be calculated using approved engineering methods to assure the return of the cement to the surface. In the event cement does not return to the surface, the district Inspector shall be notified. If the top of cement cannot be located using sound engineering practices approved by the chief or his authorized representative, then an electric log or similar technology approved by the chief shall be used. Sound engineering practice approved by the chief or his authorized representative shall be used to fill the annular space back to the surface. Requests to approve methods, other than pre-approved practices, shall be acted upon by the chief or his authorized representative within twelve (12) hours of actual notice to the chief or his authorized representative, otherwise the request will be deemed approved. In no case shall the fresh water casing penetrate salt water or extend below sea level. There shall be no oil and gas production through the fresh water casing for new wells or the redrilling of existing wells permitted on or after August 1, 1993. Variances from the requirements of this section shall be granted on a site specific or area basis in accordance with section 16 of this rule.5.2. Casing When Drilling Encounters Coal Seams.5.2.a. Coal Protection String - Except for those coalbeds which the coalbed methane operator proposes to complete for production or produce from, or where a ventilation hole is being converted to a well, when a well penetrates one or more workable coalbeds, the well operator shall run and cement a string of casing in the hole through the workable coalbed or beds in such a manner as will exclude all oil, gas or gas pressure from such coalbed or beds, except such oil, gas or gas pressure as may be naturally present in each coal seam. Such string of casing shall have cement circulated in the annular space outside the casing. The casing shall either be cemented to the surface or at least into the fresh water casing to at least 100 feet above the uppermost workable coal seam. If the casing is not cemented to the surface, the operator will demonstrate that the casing has been cemented to 100 feet above the uppermost workable coal seam. The volume of cement needed shall be calculated using approved methods to assure cementing to the required level. In the event cement does not return to the required level, every reasonable attempt will be made to fill the annular space by introducing cement from the surface. The fresh water casing may be extended through the workable coal seams and also serve as the coal protection string provided the casing is cemented as required in subsection 5.1 through the fresh water horizons, and subsection 5.2 through the workable coal seams, and subdivision 5.2.b regarding when a worked-out coal seam is encountered.
5.2.b. When Drilling Encounters a Mined Zone - Except where the horizon of a previously mined coalbed and its associated gob are expected to be the producing zone, when a coalbed methane well is drilled through the horizon of a coalbed from which the coal has been removed, the hole shall be drilled at least thirty feet below the coalbed, of a size sufficient to permit the placing of a liner which shall start not less than 20 feet below the coal seam and extend not less than 20 feet above the void created by the mined area. This liner, which may be welded to the casing being used, shall be centered in the borehole, and the space between the liner and casing shall be filled with cement as they are lowered into the hole. Cement shall be placed in the bottom of the hole to a depth of at least 20 feet to form a sealed seat for both liner and casing. Following the setting of the liner, drilling shall proceed in the manner provided in subdivision 5.2.a. Should it be necessary to drill through the horizon of two or more workable coalbeds from which the coal has been removed, such liner shall be started not less than 20 feet below the lowest such horizon penetrated and shall extend to a point not less than 20 feet above the highest such horizon, provided that, where two or more horizons from which the coal has been removed are sufficiently far apart, separate liners for each horizon or combination of horizons from which coal has been removed may be used. In any event, each segment of liner shall start not less than 20 feet below the lowest such horizon penetrated and extend to a point not less than 20 feet above the highest such horizon.
5.3. For gob wells, drilled after the effective date of this rule and vent holes converted to gob wells, a single string of casing may be used as the fresh water, coal protection and the production casings. In any event, a string of casing shall extend 30 feet below the deepest fresh water horizon (that being the deepest horizon which will replenish itself and from which fresh water or usable water for household, domestic, industrial, agricultural, or public use may be economically and feasibly recovered). Such casing shall have cement circulated in the annular space outside the casing. The volume of cement needed shall be calculated using approved methods to assure the return of cement to the surface. In the event cement does not return to the surface, every reasonable attempt will be made to fill the annular space by introducing cement from the surface.5.4. Production Casing - For all coalbed methane wells, production casing shall, through cementing or other mechanical means such as a packer, be set in such a manner as to prevent the migration of stimulation pressure or fluid, or any produced gas or water into the space between the well bore or any other casing set and the production casing. The coal protection string may also serve as the production casing. However, if the fresh water casing and the coal protection string are the same as provided for in subdivision 5.2.a, then a separate string of casing shall be used as the production string, except for those wells as provided for in subsection 5.3.
5.5. Cement Type and Strength - When cement is used to fill the annular space around the casing required in this section, it shall be American Petroleum Institute Class A Ordinary Portland Cement with no greater than three percent (3%) calcium chloride; provided that, if the coalbed methane operator furnishes satisfactory proof that different cement types are adequate, the chief may approve use of such different cement types. The cement placed in the annular space around the casing shall be allowed to set to a minimum compressive strength of five hundred (500) pounds per square inch using approved engineering data for the type of cement used, or the waiting time for all cement used shall not be less than eight (8) hours.
5.6. Variances from Cementing Requirements - The chief may also allow, upon sufficient proof by the coalbed methane operator that it will not affect mine safety or fresh water aquifers and upon consent of all coal owners or operators effected, variances from the requirement of subdivision 5.2.1, and subsections 5.4 and 5.5 regarding the cementing of the coal protection and/or the production casing along its full length.5.7. Drilling Practices Prior to Freshwater Casing - Prior to the cementing of the freshwater casing as required by subsection 5.1, drilling practices and procedures, such as air or water pressure and soaping, shall be conducted using operating practices so as to minimize damage or disturbance or the possibility of unnecessary damages or disturbance to the uncased strata/formations and groundwater contained in any of those formations. The requirements of this section shall not prevent the use of drilling practices and procedures reasonably necessary to the successful drilling of the well in a safe manner. The requirements of this section shall not be construed to prohibit practices specifically allowed by statute or other regulation.5.8. Blowout Prevention Training - The well operator shall assure that at all times during the operation of the drilling rig a person shall be present that has successfully completed a training course on blowout prevention approved by the chief.5.9. Well Identification - Every well shall have attached or stamped, in a permanent manner, the API identification number which consists of the state (047), county (001 through 109), and permit number. Such number shall be no less than one half (1/2) inch in height and detectable by any interested person approaching the well. Any additional information the well operator desires to display may be incorporated in such a manner that it will not confuse or distort the permanent API identification number.