4 Va. Admin. Code § 25-150-610

Current through Register Vol. 41, No. 8, December 2, 2024

Section 4VAC25-150-610 - Casing requirements for coalbed methane gas wells

A. Water protection string.

1. Except as provided in subdivision A 5 of this section, the permittee shall set a water-protection string set to a point at least 300 feet below the surface or 50 feet below the deepest known groundwater horizon, whichever is deeper, circulated and cemented to the surface. If cement does not return to the surface, every reasonable effort shall be made to fill the annular space by introducing cement from the surface.

2. The operator shall test or require the cementing company to test the cement mixing water for pH and temperature prior to mixing the cement and to record the results on the cementing ticket.

3. After the cement is placed, the operator shall wait a minimum of eight hours and allow the cement to achieve a calculated compressive strength of 500 psi before drilling, unless the director approves a shorter period of time. The wait-on-cement time shall be recorded within the records kept at the drilling rig while drilling is taking place.

4. When requested by the director, the operator shall submit copies of cement tickets or other documents that indicate the above specifications have been followed.

5. A coal-protection string may also serve as a water protection string only for gob wells.

B. Coal protection strings.

1. When any well penetrates coal seams that have not been mined out, the permittee shall, except as provided in subdivisions B 2 and B 3 of this section, set a coal-protection string. The coal-protection string shall exclude all fluids, oil, gas, and gas pressure, except that which is naturally present in each coal seam. The coal-protection string shall also exclude all injected material or disposed waste from the coal seams or the wellbore. The string of casing shall be set to a point at least 50 feet below the lowest coal seam, or as provided in subdivision B 3 of this section, and shall be circulated and cemented from that point to the surface, or to a point not less than 50 feet into the water-protection string or strings which are cemented to the surface.

2. For good cause shown, either before or after the permit is issued, when the procedure specified in subdivision B 1 of this section is demonstrated by the permittee as not practical, the director may approve a casing program involving:

a. The cementing of a coal-protection string in multiple stages;

b. The cementing of two or more coal-protection strings; or

c. The use of other alternative casing procedures.

3. The director may approve the program, provided he is satisfied that the result will be operationally equivalent to compliance with the provisions of subdivision B 1 of this section for the purpose of permitting the subsequent safe mining through the well or otherwise protecting the coal seams as required by this section. In the use of multiple coal-protection strings, each string below the topmost string shall be cemented at least 50 feet into the next higher string or strings that are cemented to the surface and be verified by a cement top log.

4. Depth of coal-protection strings.

a. A coal-protection string shall be set to the top of the red shales in any area underlain by them unless, on a showing by the permittee in the permit application, the director has approved the casing point of the coal-protection string at some depth less than the top of the red shales. In such event, the permittee shall conduct a gamma-ray/density log survey on an expanded scale to verify whether the well penetrates any coal seam in the uncased interval between the bottom of the coal-protection string as approved and the top of the red shales.

b. If an unanticipated coal seam or seams are discovered in the uncased interval, the permittee shall report the discovery in writing to the director. The permittee shall cement the next string of casing, whether a part of the intermediate string or the production string, in the applicable manner provided in this section for coal-protection strings, from a point at least 50 feet below the lowest coal seam so discovered to a point at least 50 feet above the highest coal seam so discovered.

c. The gamma-ray/density log survey shall be filed with the director at the same time the driller's log is filed under 4VAC25-150-360.

d. When the director believes, after reviewing documentation submitted by the permittee, that the total drilling in any particular area has verified the deepest coal seam higher than the red shales, so that further gamma-ray/density logs on an expanded scale are superfluous for the area, he may waive the constructing of a coal-protection string or the conducting of such surveys deeper than 100 feet below the verified depth of the deepest coal seam.

C. Coal-protection strings of wells drilled prior to July 1, 1982. In the case of wells drilled prior to July 1, 1982, through coal seams without coal-protection strings as prescribed in subsection B of this section, the permittee shall retain such coal-protection strings as were set. During the life of the well, the permittee shall, consistent with a plan approved by the director, keep the annular spaces between the various strings of casing adjacent to coal seams open to the extent possible, and the top ends of all such strings shall be provided with casing heads, or such other approved devices as will permit the free passage of gas or oil and prevent filling of the annular spaces with dirt or debris.

D. Producing from more than one stratum. The casing program for any well designed or completed to produce from more than one stratum shall be designed in accordance with the appropriate standard practices of the industry.

E. Casing through voids.

1. When a well is drilled through a void, the hole shall be drilled at least 30 feet below the void. The annular space shall be cemented from the base of the casing up to the void, and every reasonable attempt shall be made to fill up the annular space from the top of the void to the surface; or it shall be cemented at least 50 feet into the next higher string or strings of casing that are cemented to the surface, and shall be verified by a cement top log.

2. For good cause shown, the director may approve alternate casing procedures proposed by the permittee, provided that the director is satisfied that the alternative casing procedures are operationally equivalent to the requirements imposed by subdivision E 1 of this section.

3. For good cause shown, the director may impose special requirements on the permittee to prevent communication between two or more voids.

F. A well penetrating a mine other than a coal mine. In the event that a permittee has requested to drill a well in such a location that it would penetrate any active mine other than a coal mine, the director shall approve the safety precautions to be followed by the permittee prior to the commencement of activity.

G. Production casing.

1. Unless otherwise granted in a variance from the director:

a. For coalbed methane gas wells with cased completions and cased/open hole completions, production casing shall be set and cemented from the bottom of the casing to the surface or to a point not less than 50 feet into the lowest coal-protection or water-protection string or strings which are cemented to the surface.

b. For coalbed methane gas wells with open hole completions, the base of the casing shall be set to not more than 100 feet above the uppermost coalbed which is to be completed open hole. The casing shall be cemented from the bottom of the casing to the surface or to a point not less than 50 feet into the lowest coal-protection or water-protection string or strings which are cemented to the surface.

2. A coal-protection string may also serve as production casing.

H. Reporting of lost circulation zones. The permittee shall report to the director as soon as possible when an unanticipated void or groundwater horizon is encountered that results in lost circulation during drilling. The permittee shall take every necessary action to protect the lost circulation zone.

4 Va. Admin. Code § 25-150-610

Derived from VR480-05-22.1 §3.7, eff. September 25, 1991; amended, Virginia Register Volume 15, Issue 2, eff. November 11, 1998; Errata, 15:6 VA.R. 938 December 7, 1998; amended, Volume 29, Issue 3, eff. November 8, 2012; Volume 30, Issue 1, eff. October 10, 2013; Amended, Virginia Register Volume 33, Issue 07, eff. 12/28/2016.

Statutory Authority: §§ 45.1-161.3, 45.1-361.4, and 45.1-361.27 of the Code of Virginia.