Permanent Sealant for Oil and Gas Wells
Approved for funding in 2012, the project demonstrates Seal Well’s bismuth-based metal alloy as a sealant for oil and gas wells. By its completion in 2015, the project proved that the well-sealing technology is a more effective repair sealant for gas leakage and a superior permanent sealant for abandoned and CO2 sequestration wells.
The technology is a more effective permanent sealant than cement squeeze for plugging abandoned wells. The alloy can block natural gas leakage, including surface casing vent flow (SCVF), through the cemented annulus between the production casing and wellbore wall of producing and abandoned wells. Additionally, the alloy can permanently seal wells for CO2 sequestration projects that penetrate geologic formations where CO2 is injected. The bismuth-tin alloy is molded in situ as the well casing and cemented annulus sealing material, enabling a reliable and economic method to permanently seal greenhouse gas (GHG) emitting wells.
Testing Proves Sealant’s Long-Term Superiority
The project tested the technology on known SCVF leaks and casing plug well applications at eight wells. The methane flow rates of seven wells were reduced to zero, and the remaining wells’ flow rate diminished to one-third, proving the bismuth-tin alloy to be a superior repair sealant for SCVF problems and a permanent sealant for abandonment plugging of wells. Results of corrosion testing show that plugs in wells molded from the alloy are expected to have a service life of thousands of years, useful for sealing CO2 sequestration wells. Deployment in wells around Alberta showed the success of the alloy on well conditions with pressures exceeding regulatory requirements. Despite the long-term superiority and GHG benefit, the technology is more expensive than regulated well abandonment procedures, making it difficult to sell to an industry that is especially cost-conscious about non-standard technologies.
What’s next?
Cost competitiveness and industry inertia challenges contributed to slow market adoption, and more field demonstrations are needed to gain industry credibility. Post-project, Alberta Innovates awarded funding to a Phase 2 involving necessary field demonstrations in 2016. The follow-on, unable to garner industry support due to the economic state of the petroleum industry at the time, was delayed. In 2019, Seal Well gained approval from Natural Resources Canada as part of the Clean Growth Program to expand the scope of the project and offer incentives to well operators to participate in testing. Partnering with Tier 1 Energy Services and others, for the field demonstration, the active project is deploying the technology in Alberta and Saskatchewan, aiming to prove the alloy as less expensive and more reliable than traditional well sealing methods and garner industry and regulator acceptance.