Methods for Maintaining Zonal Isolation in A Subterranean Well
AssigneeSchlumberger Technology Corporation
InventorsFatma Daou, Bernhard Lungwitz
Life of this patent
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Abstract
A cement for use in wells in which hydrogen sulfide is present, 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 hydrogen sulfide. The swelling seals voids in the cement matrix, or along the bonding interfaces, thereby restoring zonal isolation.
Claims20
A method for maintaining zonal isolation in a subterranean well having a borehole in which hydrogen sulfide is present, comprising:
- (i) installing a tubular body inside the borehole of the well, or inside a previously installed tubular body;
- (ii) pumping an aqueous cement slurry comprising a material that swells when contacted by hydrogen sulfide 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 hydrogen sulfide;
- and
- (v) allowing the material to swell, thereby restoring zonal isolation.
A method for cementing a subterranean well having a borehole in which hydrogen sulfide is present, comprising:
- (i) installing a tubular body inside the borehole of the well, or inside a previously installed tubular body;
- (ii) pumping an aqueous cement slurry comprising a material that swells when contacted by hydrogen sulfide 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 hydrogen sulfide;
- and
- (v) allowing the material to swell, thereby restoring zonal isolation.
Dependencies are inferred from the claim text.