Methods for maintaining zonal isolation in a subterranean well
AssigneeSchlumberger Technology Corporation
InventorsHelene Bulte-Loyer, Loic Regnault de la Mothe
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Abstract
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.
Claims11
A method for maintaining zonal isolation in a subterranean well having a borehole in which hydrogen sulfide is present, comprising:
- (i) pumping a cement slurry comprising a material that swells when contacted by hydrogen sulfide into the borehole;
- and
- (ii) allowing the cement slurry to set and harden to form a cement matrix,
- wherein, upon exposure to wellbore fluids containing hydrogen sulfide at a concentration higher than about five moles per liter, a normalized flow rate reduction of at least 97 percent takes place through the cement matrix,
- wherein the material consists of polypropylene.
A method for cementing a subterranean well having a borehole in which hydrogen sulfide is present, comprising:
- (i) pumping an aqueous cement slurry into the borehole, the cement slurry comprising a material that swells when contacted by hydrogen sulfide;
- and
- (ii) allowing the cement slurry to set and harden to form a cement matrix,
- wherein, upon exposure to wellbore fluids containing hydrogen sulfide at a concentration higher than about five moles per liter, a normalized flow rate reduction of at least 97 percent takes place through the cement matrix,
- wherein the material consists of polypropylene.
Dependencies are inferred from the claim text.