Methods for Maintaining Zonal Isolation in A Subterranean Well

摘要

A cement for use in wells in which carbon dioxide is injected, stored or extracted, comprises elastomer particles. In the event of cement-matrix failure, or bonding failure between the cement/casing interface or the cement/borehole-wall interface, the elastomer particles swell when contacted by carbon dioxide. The swelling seals voids in the cement matrix, or along the bonding interfaces, thereby restoring zonal isolation.

主权项

1. A method for maintaining zonal isolation in a subterranean well having a borehole in which carbon dioxide is injected, stored, extracted or naturally present, comprising:
(i) installing a tubular body inside the borehole of the well, or inside a previously installed tubular body; (ii) pumping aqueous cement slurry comprising a material that swells when contacted by carbon dioxide into the borehole; (iii) allowing the cement slurry to set and harden; (iv) in the event of cement-matrix or bonding failure, exposing the set cement to wellbore fluids that contain carbon dioxide; and (v) allowing the material to swell, thereby restoring zonal isolation.