Section 435. Plugging for abandonment or plug-back operations

Article 6. Plugging and Abandonment

A. Permit requirements; variances.

1. Plugging operations shall not commence until a detailed plugging plan has been submitted to and approved by the director. A permit modification is required if the well was not previously permitted for plugging.

2. Any person may file an application with the director to replug a previously plugged well in any manner permissible under provisions of this section to facilitate the safe mining-through of the well at a later date. The application shall be treated in all respects like any other application for a permit under § 45.1-361.29 of the Code of Virginia.

3. The director may, upon application by the permittee, approve a variance to the prescribed plugging methods for the following reasons if it is determined that the alternate plan meets the requirements of the Act:

a. The coal owner or operator requests a special plugging program to facilitate mine safety, mining through the well, or to obtain approval from another governmental agency for the safe mining-through of a well. The application for a variance must include documentation of the request from the coal owner or operator.

b. The permittee has obtained written authorization from the coal owner or operator for alternate plugging of the coal-bearing section. The application for a variance must include documentation of approval by the coal owner or operator.

c. Downhole conditions such as junk in the hole, a stuck or collapsed casing, caving or other adverse conditions which would prevent proper execution of the prescribed plugging methods.

d. A permittee presents an alternate plugging plan which may differ in method from that prescribed herein, but which will achieve the desired result.

B. Plugging in open hole. When a well or section of a well without casing is to be plugged or plugged back, it shall be sealed and filled as prescribed in this section.

1. At a point approximately 20 feet above each oil, gas or water-bearing stratum in open hole, a plug shall be placed so as to completely seal the wellbore. Whenever two or more gas or oil stratum are not widely separated, they may be treated as a single stratum and plugged accordingly. Cement plugs shall be at least 100 feet in length. At least 20 feet of cement shall be placed on top of open hole bridge plugs.

2. At each coal seam, a cement plug shall be placed from not less than 50 feet below the base of the coal to not less than 50 feet above the top of the coal. Whenever two or more coal seams are not widely separated, they may be treated as a single seam and plugged accordingly. This subsection applies only to coal seams which occur at a depth compatible with mining. Coal-bearing sections at greater depths may be plugged in accordance with subdivision B 1 of this section.

3. If a source of groundwater capable of having a beneficial use is exposed in open hole below surface (water-protection) casing, a cement plug at least 100 feet in length shall be placed below the base of the lowest such groundwater zone.

4. A cement plug of a minimum length of 100 feet shall be placed across the shoe of the surface (water-protection) casing. The plug shall be placed so as to have approximately equal lengths in open hole and inside casing. If the well is without surface casing, a continuous cement plug shall be placed from at least 50 feet below the base of the lowest known aquifer or 300 feet depth, whichever is deeper, to the surface.

5. All intervals below and between plugs shall be filled with drilling mud, bentonite gel, or other appropriately weighted materials approved by the director.

C. Plugging in cased hole. When a cased hole or section of a cased hole is to be plugged or plugged back, it shall be sealed and filled as prescribed in this section.

1. All perforated intervals shall be either squeeze-cemented or otherwise isolated from the wellbore by suitable plugs placed across or immediately above the perforated interval. Cement plugs placed across perforations shall extend to at least 50 feet above the top perforations. A cement plug shall be placed to at least 50 feet above squeezed perforations. Cement plugs placed entirely above perforations shall be at least 100 feet in length. At least 20 feet of cement shall be placed on top of bridge plugs, cement retainers, or other tools left in the hole.

2. At each coal seam which is behind a properly installed and cemented coal-protection casing, a cement plug shall be placed from not less than 50 feet below the base of the coal to not less than 50 feet above the top of the coal. Whenever two or more coal seams are not widely separated, they may be treated as a single seam and plugged accordingly.

3. If casing is not to be pulled, and there is uncemented annulus behind the pipe, plugging shall be as follows:

a. Each oil, gas or water-bearing stratum present behind the pipe in an uncemented annulus must be isolated by perforating the casing at each zone and squeezing cement up into the zone, or circulating cement up the annulus such that a cement fill-up of not less than 100 feet is achieved. When squeezing or circulating the annulus, a cement plug of at least 50 feet shall be placed inside the casing above the perforations.

b. If the well penetrates a minable coal-bearing section, and no coal-protection casing was used, and if surface (water-protection) casing is either absent or not properly placed and cemented to surface, the production casing shall be converted to a coal-protection string by perforating at least 50 feet below the base of the lowest coal stratum, and circulating cement in the annulus from that point to the surface.

c. At each coal seam in a minable coal-bearing section which is protected by a properly installed and cemented coal-protection string, a cement plug shall be placed in casing from not less than 50 feet below the base of the coal to not less than 50 feet above the top of the coal. If there is uncemented annulus between the inner casing and the coal-protection string, the casing shall be perforated to allow cement to be circulated over the prescribed interval, and a plug of equal length shall be placed inside the inner casing.

d. If a fresh water aquifer is exposed to the wellbore in an uncemented annulus, it shall be isolated by perforating the casing at least 100 feet below the aquifer and squeezing cement into the annulus or circulating it up the annulus so that a fill-up of not less than 100 feet is achieved. When squeezing or circulating cement, a cement plug of at least 100 feet shall be placed inside the casing above the perforation.

e. At a point no less than 50 feet below the shoe of surface (water-protection) string, the casing shall be perforated and cement circulated up the annulus to a minimum fill-up of 100 feet. A plug of equal length shall be placed inside the casing.

f. From a point not less than 50 feet below surface, a cement plug shall be installed which reaches the surface. If any uncemented annuli are present at the surface, the voids should be filled and sealed to the greatest extent possible by introducing cement from the surface.

g. All intervals below and between plugs shall be filled with drilling mud, bentonite gel, or other appropriately weighted materials approved by the director.

4. If casing is to be pulled, plugging shall be as follows:

a. All perforated intervals shall be isolated as described in subdivision C 1 of this section.

b. Casing stubs shall be isolated by placing a plug across or above the cut-off point. Cement plugs shall be at least 100 feet in length and shall be placed so as to have approximately equal lengths inside and above the remnant casing. Permanent bridge plugs may be placed above the stub and shall be capped by at least 20 feet of cement.

D. Plugging operations involving uncemented water-protection casing or coal-protection casing.

1. If the annulus of the largest casing present across a minable coal-bearing section is not cemented across that section, then one of the two procedures listed below must be followed:

a. The casing must be perforated at least 50 feet below the lowest coal seam, and cement circulated in the annulus to the surface (if water-protection casing is absent or not properly placed and cemented to surface), or to at least 100 feet above the highest coal (if the casing is to be partially pulled to facilitate plugging operations in the fresh water zone). Plugging shall proceed according to cased hole requirements; or

b. The casing shall be pulled from the well, and plugging shall proceed according to open hole requirements.

2. If the annulus of the largest casing present across the fresh-water-bearing section is not cemented across that section, then one of the two procedures listed below must be followed:

a. The casing shall be perforated below the lowest known fresh-water zone or at a minimum depth of 300 feet. Cement shall be circulated in the annulus to the surface. Plugging shall proceed according to cased hole requirements; or

b. The casing shall be pulled from the well, and a continuous cement plug shall be placed from below the base of the lowest known fresh-water aquifer exposed to the wellbore, or 300-foot depth, whichever is deeper, to the surface.

E. Unfillable cavities. When an unfillable cavity such as a cavern, mine void, blast stimulation zone or gob completion is encountered, the section shall be plugged as follows:

1. If the stratum with the unfillable cavities is the lowest gas or oil stratum in the well, a plug shall be placed at the nearest suitable point not less than 20 feet above the stratum. Cement plugs shall be at least 100 feet long, and at least 20 feet of cement shall be placed on top of bridge plugs.

2. If the stratum with unfillable cavities is above the lowest gas or oil stratum, a plug shall be placed below the stratum and shall extend to within 20 feet of its base. A plug shall also be placed above the stratum as described in subdivision E 1 of this section.

Historical Notes

Derived from Volume 15, Issue 02, eff. November 11, 1998.

Statutory Authority

§§ 45.1-161.3 and 45.1-361.27 of the Code of Virginia.