Compositions and methods for well completions

摘要

A remedial method for damaged cement sheath, especially for use in wells in which acid gases are injected, stored or extracted. In the event of cement-matrix failure, or bonding failure between the cement/casing interface or the cement/borehole-wall interface, an aqueous slurry comprising an acid swellable material is injected into or adjacent the cement sheath so that the material swells when contacted by acid gases, including carbon dioxide and hydrogen sulfide. The swelling seals voids in the cement matrix, or along the bonding interfaces, thereby restoring zonal isolation.