Abstract: A well cementing composition comprises an aqueous fluid, portland cement, styrene-butadiene latex and styrene sulfonate-maleic acid copolymer. The styrene sulfonate-maleic acid copolymer has a molecular weight between 5,000 g/mol and 25,000 g/mol. The composition may be placed in a subterranean well during a primary cementing or a remedial cementing operation.

Abstract: A well cementing composition that includes water, portland cement, a retarder and colloidal amorphous silica, present at a concentration between 0.2% and 1.0% by weight of cement. When added at such concentrations, the colloidal amorphous silica behaves as a retarder aid at bottomhole circulating temperatures exceeding 100° C. Methods for employing these compositions in well cementing operations are also disclosed.

Abstract: Cement slurries are prepared that comprise water and a blend comprising an inorganic cement and at least one mineral. The slurries may have a solid volume fraction between 0.3 and 0.4, and the cement may be present at concentrations between 30% and 70% by volume of blend. The slurries may be placed in a subterranean well and allowed to harden and form set cements.

Abstract: Cement retarders are based on blends of lignosulfonate compounds, borate compounds and gluconate compounds. The compounds are present in certain ratios that allow the retarders to operate at temperatures and pressures up to and exceeding about 176° C. and 152 MPa. The retarders may also be provided in liquid form, improving their suitability for use at offshore well-site locations.

Abstract: Cement retarders are based on blends of lignosulfonate compounds, borate compounds and gluconate compounds. The compounds are present in certain ratios that allow the retarders to operate at temperatures and pressures up to and exceeding about 176° C. and 152 MPa. The retarders may also be provided in liquid form, improving their suitability for use at offshore well-site locations.

Abstract: Spacer fluids that are stable at temperatures up to at least 260° C. comprise water, polystyrene sulfonate and a mixture of particulate materials. The particulate materials may be chosen such that the mixture has at least a trimodal particle-size distribution. The fluids may further comprise inorganic clays, mutual solvents and surfactants.

Abstract: This invention relates to methods for servicing subterranean wells, in particular, fluid compositions and methods for remedial operations during which the fluid compositions are pumped into a wellbore and make contact with well cements placed during primary cementing or previous remedial cementing operations.

Abstract: Well-cementing compositions for use in high-pressure, high-temperature (HPHT) wells are often densified, and contain weighting agents such as hematite, ilmenite, barite and hausmannite. The weighting agents are usually finely divided to help keep them suspended in the cement slurry. At high temperatures, finely divided weighting agents based on metal oxides react with the calcium-silicate-hydrate binder in set Portland, cement, leading to cement deterioration. Finely divided weighting agents based on metal sulfates are inert with respect to calcium silicate hydrate; consequently, set-cement stability is preserved.

Abstract: Well-cementing compositions for use in high-pressure, high-temperature (HPHT) wells are often densified, and contain weighting agents such as hematite, ilmenite, barite and hausmannite. The weighting agents are usually finely divided to help keep them suspended in the cement slurry. At high temperatures, finely divided weighting agents based on metal oxides react with the calcium-silicate-hydrate binder in set Portland cement, leading to cement deterioration. Finely divided weighting agents based on metal sulfates are inert with respect to calcium silicate hydrate; consequently, set-cement stability is preserved.

Abstract: A method of cementing a well is disclosed. The method comprising pumping into the well a cement slurry comprising a solid blend including cement, water, and a fluid loss control agent, and allowing the cement slurry to set. The fluid loss control agent comprises a styrene-butadiene latex and a high molecular-weight water-soluble polymer such as a copolymer AMPS-Am. The addition of the water-soluble polymer allows drastic reduction of the quantity of latex required to achieve fluid loss control performance and even gas migration control.

Abstract: A method of cementing a well is disclosed. The method comprising pumping into the well a cement slurry comprising a solid blend including cement, water, and a fluid loss control agent, and allowing the cement slurry to set. The fluid loss control agent comprises a styrene-butadiene latex and a high molecular-weight water-soluble polymer such as a copolymer AMPS-Am. The addition of the water-soluble polymer allows drastic reduction of the quantity of latex required to achieve fluid loss control performance and even gas migration control.

Abstract: Spacer fluids that are stable at temperatures up to at least 300° C. comprise water, polystyrene sulfonate and a mixture of particulate materials. The particulate materials may be chosen such that the mixture has at least a trimodal particle-size distribution. The fluids may further comprise inorganic clays, mutual solvents and surfactants.

Abstract: This invention relates to methods for servicing subterranean wells, in particular, fluid compositions and methods for remedial operations during which the fluid compositions are pumped into a wellbore and make contact with well cements placed during primary cementing or previous remedial cementing operations.

Abstract: It is proposed a new fluid loss control agent useful for the cementation of oil or gas wells. This fluid loss control agent consists of a mixture of a styrene-butadiene latex and a high molecular weight water-soluble polymer such as a copolymer AMPS-Am. The addition of the water-soluble polymer allows drastic reduction of the quantity of latex required to achieve fluid loss control performance and even gas migration control.

Abstract: Fluid compositions containing a silica-particle suspension with no intrinsic cementitious properties may be pumped into a wellbore. Upon making downhole contact with previously placed well cements from primary-cementing or previous remedial-cementing operations, the silica suspension reacts to form a gel that seals voids, cracks or fissures in the cement sheath. Portland cement is the preferred cement with which the silica-particle suspensions interact downhole.

Abstract: Spacer fluids that are stable at temperatures up to at least 260° C. comprise water, polystyrene sulfonate and a mixture of particulate materials. The particulate materials may be chosen such that the mixture has at least a trimodal particle-size distribution. The fluids may further comprise inorganic clays, mutual solvents and surfactants.

Abstract: High-specific-gravity micronized particulates, added to cement slurries in conjunction with certain high-molecular-weight water-soluble polymers, improve fluid-loss control of cement slurries during placement in subterranean wells. The particulates may have a specific gravity higher than 3, and a median particle size smaller than 3 ?m. The particulates may include barite, manganese tetraoxide, titanium oxide, iron titanium oxide and aluminum oxide.

Abstract: Providing a solution of at least one salt capable of reacting with a set cement to form a solid phase comprising a precipitate or an expanded phase of the cement; contacting a region of the set cement to be repaired with the solution so as to form the solid phase in voids in the region of the set cement to be repaired.

Abstract: Methods for sealing voids and cracks in subterranean-formation rock that contains carbonate minerals, thereby minimizing or stopping fluid flow between the formation rock and the wellbore of a subterranean well, comprise pumping a solution of one or more lattices that contains at least one carboxylated monomer down a well during drilling and allowing it to enter voids (e.g., pores, fractures, vugs and caverns) in the carbonate-containing formation. The solution reacts with divalent cations liberated by the carbonates and forms a plug.

Abstract: Cement retarders are based on blends of lignosulfonate compounds, borate compounds and gluconate compounds. The compounds are present in certain ratios that allow the retarders to operate at temperatures and pressures up to and exceeding about 176° C. and 152 MPa. The retarders may also be provided in liquid form, improving their suitability for use at offshore well-site locations.