An abandoned well with a long history
Drilled in 1894. Abandoned in 2021
In 1894 the Geological Society of Canada (GSC) drilled their first well in an effort to find the southeastern border of the Athabasca Tar Sands. This mission alternatively exposed a formation rich in natural gas to a depth 540 meters. In 1896, operations ceased, leaving the well incorrectly abandoned and forgotten. That is, until Alberta Energy Regulator (AER) received a complaint of a gas leak that was found to be from an old wellhead buried beside the Athabasca River.
In partnership with RPS, Codeco-Vanoco Engineering Inc. was consulted to develop a plan to properly abandon the well 135 years later. Although the leak was found to be “Non-serious” as per AER Directive 20, corrections needed to be taken and it was going to require unconventional thought to address the multiple barriers that comprised this unique project.
Understandably, due to the age of the age of the well, documentation of tubulars and whether there was any subsequent work on the well was minimal. Also, casing and tubing can corrode over time and because of the age of the well casing and tubular integrity was a concern. The number of unknowns led to a decision tree being implemented to help in effectively dealing with what could be encountered once the well was re-entered.
Furthermore, the location of the well head proved to be a problem. First, it was located inside the city limits of the town of Athabasca, with a major highway running adjacent to the river and an active business and residential area nearby. Even more challenging, the well head rested a mere 3 meters away from the actual Athabasca River shadowed by the 40 degree slope of a river bank.
Finally, time was a factor. The imminent Spring thaw triggers ice flow and the potential rise in water levels. Also, road bans would be in effect March 15th and with initial planning starting January 25th 2021, little time was available to secure permits and discuss strategy. Initially, building a 650m ice road on the Athabasca River during the winter was considered to transport the heavy equipment to the site via the river. A temporary barrier, known as a cofferdam, would also need to be built to create a dry and solid area for the equipment over the well. Unfortunately, this approach would likely double the project’s budget and delay the start by one year as it was already too late in the season to begin building the road. Instead, approaching the project from another “angle” proved most effective.
Reaching the well from above using a 275 ton crane with a coil tubing rig eliminated the need to build a costly ice road. This unique access point allowed entry to the well with the least disturbance to the riverbank. The procedure was approved and implemented, and the well was re-entered and cemented correctly eliminating the gas leak ahead of schedule by 10 days. The well will continue to be monitored over the next few seasons until eventually it will be cut off below the surface, capped, and the site will be reclaimed. The community of Athabasca and the AER were grateful to have the well secured quickly with minimal disturbance.