Why are Wells Abandoned

 

Why are Wells Abandoned

Wells are abandoned because they are no longer needed to support oil and gas development or because an operator’s mineral lease has expired.

After many decades of energy development, abandoned wells are common in Alberta. As of June 2013, approximately 151 000 abandoned wells exist in Alberta, representing 35 per cent of all wells in the province.

Under Directive 020: Well Abandonment, the AER has set strict requirements for environmental protection and public safety in areas around abandoned wells.

Before a well is abandoned, the licensee must inform all affected landowners about the proposed abandonment. Licensees are also required to test the well to ensure that it will not pose any risk to the environment or the public once abandoned. If any issues are found during the testing phase, the licensee must make all necessary modifications according to AER requirements.

Abandoning Oil and Gas Wells
To ensure the safe and effective abandonment of oil and gas wells, all operators must follow the process defined by the AER:

  1. Identification and Creation of a Project Plan
    The operator must design an abandonment program that identifies any wellbore integrity issues, all oil or gas formations, and all groundwater zones. They must also evaluate the cement present in the well.
  2. Execution and Implementation
    The next step is to clean the inside of the wellbore, removing any oil and gas that may cause the casing to corrode or limit the effectiveness of abandonment cement plugs. Any issues identified within the wellbore must be repaired. In addition, all porous formations must be isolated from one another and any groundwater zones isolated from the wellbore with cement. The well is then filled with nonsaline water or other noncorrosive fluid and is assessed to ensure the long-term integrity of the well.
  3. Finalization – Surface Abandonment
    The final step in the abandonment process is known as the “cut and cap” of a well, which involves cutting the well casing a minimum of one metre below the surface and placing a vented cap atop the well casing. All surface equipment associated with the well must also be removed within 12 months of the completion of the cut-and-cap process.

Abandoned Wells and Potential Risks
Given the strict requirements imposed on licensees, the AER does not anticipate any issues living or working near an abandoned well.

While abandoned wells do not place the environment or public at significant risk, small leaks are possible. A well leak can be caused by many things, including corrosion, improper abandonment, and damage incurred during excavation.

If an abandoned well begins to leak, the licensee must notify the AER immediately. An application must be submitted to the AER and approval given before the licensee can re-enter the abandoned well to repair the leak.

Gas detection tests are used to identify any leaks and determine if any gases are present. These tests are conducted by the licensee and all subsequent results are reported to the AER. Should a gas detection test find a leak, the licensee must meet with the appropriate landowners to discuss an appropriate course of action.