Casing Expansion Tool to Shut Off Methane Leaks in Wells
Approved for funding through ERA’s Partnership Intake Program in 2020, this project involved trialing Winterhawk’s Casing Expansion Technology (CET) in seven oil and gas wellbores with known surface casing vent flows (SCVFs). SCVF is the uncontrolled flow of gas or liquid out of the well casing annulus. By its completion in 2022, the project proved the CET tool’s performance and effectiveness in reducing or mitigating methane leaks.
Winterhawk’s CET tool is a lower cost method of reducing and mitigating the leakage from the annulus of wellbores for the oil and gas industry. The tool functions by expanding the casing in the wellbore, compressing the cement, squeezing shut gas migration cracks, and re-sealing the annulus, or the region between the casing and the side of the wellbore. This technology addresses SCVF, which accounts for three percent of methane emissions in Alberta, that are historically difficult and costly to remediate.
Due to industry disruption from COVID-19, along with regulatory approval and issues securing a partner, field-testing of the CET was reduced from 30 wells to seven. Although evaluating the performance of the CET was achieved, expected project emissions reductions were not, due to the reduced number of wells available by industry partners.
Less Restrictive Regulation Required to Realize Full Potential
The project demonstrated that the tool successfully expands casing when and where required and can be easily recovered from the well. Additionally, CET proved to be a valuable diagnostic tool by identifying the depth methane flows within wells by monitoring surface performance during expansion, identifying the ideal annulus properties for creating permanent seal, and ensuring cement squeezes are successful by providing a vertical barrier confining the cement flow outside the casing. All of this is extremely valuable for effective SCVF mitigation.
During the project, it was discovered that improved and more cost-effective tools to examine wellbore annulus are needed. SCVF shutoff using casing expansion is new, therefore considered ‘non-routine’ abandonment by AER, and this restricted CET’s use to lower sections of the wellbore. Therefore, even though CET is successful at reducing or eliminating methane leaks at the intervals it was used, it did not achieve complete shutoff of methane flow in most cases due to only being able to deploy in prescribed intervals as per regulatory approval.
What’s next?
During the project, CET for 4 ½-inch casing was developed due to client demand. CET for 4 ½-inch casing can be deployed in the greatest number of leaking wellbores, as it’s used in the mature gas producing areas of central and southeast Alberta. This presents a significant market opportunity for deployment in future wellbores. Casing expansion can solve additional wellbore problems to vent flow. The company is attracting interest from bitumen producers in heavy oil thermal projects to improve wellbore integrity and from producers with extended reach horizontal wells to repair distorted casing caused by hydraulic fracturing.