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Case Study: Preserve Cement Sheath Integrity for the Life of the Well



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Gas shut-off test conducted at ambient temperatures and 21 MPa (3,000 psi). Initial flow rate is established using nitrogen gas (shown in blue), after which the system switched to natural gas. After 30 min, FUTUR active set-cement technology reduced the flow to negligible quantities.

Suncor Energy uses FUTUR active set-cement technology to mitigate risk of future gas leaks in Central Alberta Foothills

Challenge
Gas migration and resulting surface casing vent flow (SCVF) from shallow gas-bearing formations.

Solution
FUTUR active set-cement technology, which automatically closes cracks in the cement sheath when exposed to hydrocarbons.

Results
Enhanced well integrity with no signs of pressure build-up or gas flows to surface after more than 1 year after cementing operations.

Suface casing leaks threaten well integrity

Suncor Energy frequently encounters shallow gas formations when drilling heavy-oil wells in the Central Alberta Foothills. Cement sheath damage or debonding can allow nuisance gas from these formations to migrate to surface resulting in surface casing vent flows or sustained casing pressure (SCP). The presence of such flows can require a well to be shut in for remediation or abandoned altogether.

The issue is not unique to the Central Alberta Foothills region. There are thousands of wells in Central Europe, the Middle East, the US, and Canada that suffer SCP or SCVF. When the cement sheath is damaged and hydrocarbons begin to flow, confirming that damage or its location can be difficult. Actually fixing the damage in order to restore well integrity can be expensive or impractical.

New cement technology preserves producing wells

FUTUR active set-cement technology provides long-term zonal isolation and prevents the flow of hydrocarbons through potential leak paths up and along the annulus. Any hydrocarbon that comes into contact with FUTUR active set-cement technology will activate the self-healing properties of this unique sealant material. Once activated, cracks or fissures in the cement sheath are healed, and the hydraulic seal is reestablished, eliminating the need to suspend production in order to perform remedial operations. Even if the cement sheath is damaged again, FUTUR active set-cement technology will continue to self-repair on multiple, independent occasions.

To distribute an effective long-term seal throughout the well, this responsive self-healing cement can be strategically placed behind any string of casing as part of normal primary cementing operations. FUTUR cement systems continue to work for the life of the cement sheath, reactivating when hydrocarbon leaks occur during production or after abandonment. The responsive material eliminates the need for well intervention by ensuring long-term protection and preventing costly repairs.

Tests confirm no annular or gas flow

The slurry incorporating FUTUR active set-cement technology was mixed using standard cementing equipment and procedures and pumped just like standard cement. The cement design was adjusted for the anticipated well and drilling fluid conditions. More than 1 year after implementation, the wells show no signs of pressure build-up in the annulus or at surface.


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