Exedra secures funding for advanced well plugging tests

Exedra has received 5.1 MNOK in funding from the Norwegian Research Council to enhance testing of its well-plugging verification technology.

Exedra is both a member and cluster project at Energy Transition Norway, and it is one of six Norwegian companies highlighted in the Research Council's article announcing which 32 projects will receive NOK 317 million in funding in 2025.

With an additional support from Equinor and TotalEnergies, Exedra is set to start a new R&D project, including a field trial in Texas in 2025.

The purpose of the project is to better understand how a mixture of gas and liquid from a reservoir can leak through different types of permanent barriers. This insight will then help the industry to develop numerical models to estimate possible leak rates - crucial to better understand risks associated with permanent plugging of oil and gas wells.  

– We are very pleased to have Equinor and TotalEnergies on board in this project. We are welcoming  more partners on board along the way, says CEO Bernt Pedersen.

Tackling gas-tight well plugging

Thousands of oil and gas wells are permanently plugged each year. Without a proven way to verify the plugs’ integrity, it’s difficult to introduce new, cost-saving plugging methods, like for instance shorter plugs or new plugging materials.

To be sure plugged wells are not leaking, Norwegian regulations and guidelines require several sealing barriers in the wells. Plugging a well also requires pulling out hundreds of meters of steel tubing. This requires an expensive drilling rig, and can require many weeks with a bid drilling crew.  

The cost can reach as much as 200 million NOK per well, where most of this is covered by the state.  

On the Norwegian Continental Shelf alone, operators will need to plug around 3,000 wells in the coming decades. Without more efficient plugging solutions this will cost our society hundreds of billions. In addition the plugging operations will emit significant amounts of CO2.

And globally, up to one-fourth of the plugged wells are expected to leak, as the industry lacks affordable and reliable ways to verify that the plugged wells are completely leak tight.

Exedra has developed a new way to detect leaks

A special tool is placed below the barrier that is to be tested. Once the plug has cured, a tracer gas is released below the plug. If the plug leaks, the tracer molecules are detected using a very sensitive detected above the barrier, and an alarm will go off. If no tracer molecules are detected, one can conclude that the barrier is leak tight.

To make this method even better, researchers are studying how tracer gas moves through different sealing materials. Key questions include how long it takes for gas and liquid to pass through a barrier and how much gas can escape through these leaks.

– The insights from this research project will help create a numerical leak estimator, aiding the industry in transitioning to new, cost-effective plugging technologies, Pedersen explains.

This technology will not only reduce costs but also lower greenhouse gas emissions and mitigate the risk of abandoned wells leaking in the future.

Key innovations

The R&D project will  focus on three cost-saving plugging technologies:

(1) Bismuth-based plugs – Special metal alloys that melts at a low temperature, and then cures to create a tight seal, blocking gas from escaping.

(2) Tubing left in hole (TLIH) – Keeps steel pipes in the well so that plugging can be done using a smaller, cheaper vessel (Light Well Intervention Vessel) instead of an expensive drilling rig.

(3) Dual PWC (Perforate, Wash, and Cement) – Uses controlled explosions to create a solid barrier inside the well, sealing it without having to remove large steel casings, which saves time and money.

Exedra’s next slim hole monitoring tool, will monitor plug integrity over time, ensuring long-term sealing.

With HavTIL (ex Petroleum Safety Autority) as part of its steering committee and a partnership with the Net Zero Technology Centre in Aberdeen, Exedra is making sure it meets regulations and market demands, also in the UK, where around 200 wells are being plugged each year.