method for maintaining zonal isolation in an underground well having a hole in which hydrogen sulfide is present, and method for cementing an underground well having a hole in which hydrogen sulfide is present

摘要

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