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.

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.

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.

Abstract: In a method of treating a sandstone-containing formation penetrated by a wellbore, a treatment fluid comprising an aqueous fluid containing a Bronsted acid, a hydrogen fluoride source and an organic acid or salt thereof that is substantially soluble in the aqueous fluid is formed. The treatment fluid contains less than about 2% of fluoride (F?) by weight of the fluid and from 2% or less of sodium (Na+) by weight of the fluid. The treatment fluid is introduced into the formation through the wellbore as a single-stage without introducing an acid-containing fluid preflush into the formation prior to introducing the treatment fluid.

Abstract: In a method of treating a sandstone-containing formation penetrated by a wellbore, a treatment fluid comprising an aqueous fluid containing a Bronsted acid, a hydrogen fluoride source and an organic acid or salt thereof that is substantially soluble in the aqueous fluid is formed. The treatment fluid contains less than about 2% of fluoride (F?) by weight of the fluid and from 2% or less of sodium (Na+) by weight of the fluid. The treatment fluid is introduced into the formation through the wellbore as a single-stage without introducing an acid-containing fluid preflush into the formation prior to introducing the treatment fluid.

Abstract: Methods of characterizing the self-healing properties of a set cement based material in contact with hydrocarbons in an oil- and/or gas-well are described. The methods comprise: providing a test cell (10); providing said test cell (10) with a sample (31, 40) of the set cement based material; damaging the sample to simulate a loss of zonal isolation resulting from damages made to the set cement based material in the oil- or gas-well; injecting a hydrocarbon fluid in the test cell; allowing the cement based material to heal by itself; measuring the differential pressure (?P) across the sample (31, 40); and characterizing the self-healing properties of the cement based material from the measure of said differential pressure (?P).

Abstract: Methods of characterizing the self-healing properties of a set cement based material in contact with hydrocarbons in an oil- and/or gas-well are described. The methods comprise: providing a test cell (10); providing said test cell (10) with a sample (31, 40) of the set cement based material; damaging the sample to simulate a loss of zonal isolation resulting from damages made to the set cement based material in the oil- or gas-well; injecting a hydrocarbon fluid in the test cell; allowing the cement based material to heal by itself; measuring the differential pressure (?P) across the sample (31, 40); and characterizing the self-healing properties of the cement based material from the measure of said differential pressure (?P).

Abstract: In a method of treating a sandstone-containing formation penetrated by a wellbore, a treatment fluid comprising an aqueous fluid containing a Bronsted acid, a hydrogen fluoride source and an organic acid or salt thereof that is substantially soluble in the aqueous fluid is formed. The treatment fluid contains less than about 2% of fluoride (F?) by weight of the fluid and from 2% or less of sodium (Na+) by weight of the fluid. The treatment fluid is introduced into the formation through the wellbore as a single-stage without introducing an acid-containing fluid preflush into the formation prior to introducing the treatment fluid.

Abstract: In a method of treating a sandstone-containing formation penetrated by a wellbore, a treatment fluid comprising an aqueous fluid containing a Bronsted acid, a hydrogen fluoride source and an organic acid or salt thereof that is substantially soluble in the aqueous fluid is formed. The treatment fluid contains less than about 2% of fluoride (F?) by weight of the fluid and from 2% or less of sodium (Na+) by weight of the fluid. The treatment fluid is introduced into the formation through the wellbore as a single-stage without introducing an acid-containing fluid preflush into the formation prior to introducing the treatment fluid.