The present invention describes a hydraulic cement composition, its obtaining process and its use. More precisely, the hydraulic cement composition comprises increased resistance to CO.sub.2 for application in subsurface fluid reservoirs.

A cement composition is provided. The cement composition comprises: a microcapsule and cement. The microcapsule is provided with a core-shell structure having i) a core containing a water-repellent organosilicon material selected from the group consisting of organosilanes, organosilane partial condensation products, and branched siloxane resins, and ii) a shell of a silicon-based network polymer containing a silica unit. The microcapsule is included at 0.01 to less than 0.5 parts by weight per 100 parts by weight of the cement. Thus, it is possible to provide a cement composition that can provide a cured product having high strength, as well as excellent air content stability, substance penetration prevention, drying shrinkage, and freeze-thaw resistance.

A carbonation-resistant cementitious blend containing cement, an expandable agent present, a dispersion agent, a fluid loss additive, a defoamer, and an olive waste. Concrete samples made therefrom and methods of producing such concrete samples are also specified. The addition of olive waste provides enhanced durability (carbonation resistance) and maintains mechanical strength (e.g. compressive strength, tensile strength) after exposure to CO.sub.2 and/or brine. The resulting concretes are suitable cementing material for oil and gas wells as well as wellbores for geologic carbon sequestration.

The disclosure relates to a method for controlling carbonation synthesis of silicon and/or aluminium carbonate minerals, wherein the concentration of dissolved silicon and/or aluminium in a mix to be cured is adjusted to at least 1 mmol/1 before curing he mix with gas comprising carbon dioxide (CO.sub.2) having a partial pressure of CO.sub.2 of at least 0.15 bar. In some embodiments of the isclosure an alkaline substance is added to the raw material to provide the mix where the total concentration of dissolved silicon and/or aluminium of at least 1 mmol/l. The disclosure also relates to a product obtainable by the methods of the disclosure as well as to the use of the product as building material, preferably for producing concrete-like products, more preferably for elements, most preferably for pre-casted elements and to the use of the method in construction industry or for production of elements and/or pre-casted elements.

Provided are a concrete manufacturing method capable of preventing neutralization of concrete and oxidation of a reinforcing rod in reinforced concrete, and a method for manufacturing a reinforced concrete structure using the same. The concrete manufacturing method uses nitrogen dissolved water and is characterized by including: a step of generating nitrogen dissolved water by injecting nitrogen gas into water to replace oxygen and carbon dioxide dissolved in the water with nitrogen; and a step of generating a ready-mixed concrete by kneading the nitrogen dissolved water, cement, an aggregate, and an admixture. The method for manufacturing a reinforced concrete structure is characterized by forming a reinforced concrete structure using a ready-mixed concrete manufactured by a concrete manufacturing method using nitrogen dissolved water.

Provided are a concrete manufacturing method capable of preventing neutralization of concrete and oxidation of a reinforcing rod in reinforced concrete, and a method for manufacturing a reinforced concrete structure using the same. The concrete manufacturing method uses nitrogen dissolved water and is characterized by including: a step of generating nitrogen dissolved water by injecting nitrogen gas into water to replace oxygen and carbon dioxide dissolved in the water with nitrogen; and a step of generating a ready-mixed concrete by kneading the nitrogen dissolved water, cement, an aggregate, and an admixture. The method for manufacturing a reinforced concrete structure is characterized by forming a reinforced concrete structure using a ready-mixed concrete manufactured by a concrete manufacturing method using nitrogen dissolved water.

A method may include: introducing a resin modified cement slurry into a wellbore penetrating a subterranean formation, the subterranean formation comprising a caprock and a carbon dioxide injection zone, the resin modified cement slurry comprising: a resin; a hardener; a hydraulic cement; and water; and setting the resin modified cement slurry to form a set cement wherein the set cement forms a carbonation-resistant barrier in the carbon dioxide injection zone in the subterranean formation.

The present invention describes a hydraulic cement composition, process and use thereof, wherein the composition comprises a hydraulic cement composition with increased resistance against carbon dioxide (CO.sub.2) for application in reservoirs such as oil and gas and carbon capture and storage (CCS) wells; with improved performance of cement paste formulations as a material for application in primary, secondary cementing, recovery and/or plugging operations, of reservoirs/wells that operate with high CO.sub.2 content; as a technological alternative to guarantee the integrity of wells in CO.sub.2-rich environments for long periods of time, without any additional intervention to the already current operational procedures for cementing wells, and with cost reduction in relation to class G cement (currently, the main raw material); and sufficient chemical resistance to carry out enhanced oil (EOR) and gas (EGR) recovery by injecting high levels of CO.sub.2, increasing reservoir pressure throughout the extraction period of hydrocarbon reservoirs.

A method may include: introducing a resin modified cement slurry into a wellbore penetrating a subterranean formation, the subterranean formation comprising a caprock and a carbon dioxide injection zone, the resin modified cement slurry comprising: a resin; a hardener, a hydraulic cement; and water; and setting the resin modified cement slurry to form a set cement wherein the set cement forms a carbonation-resistant barrier in the carbon dioxide injection zone in the subterranean formation.

The invention relates to the use of calcium nitrate to reduce the pore size distribution of a hardened cementitious composition, preferably, a hardened concrete composition, wherein the cementitious (concrete) composition comprises between 1 weight % to 4 weight % of calcium nitrate of the cement content of the cementitious composition, depending on the type of cement. This results in a reduced permeability for the set cementitious (concrete) composition for carbon dioxide (CO.sub.2) and thus an elevated resistance towards carbonation. The invention furthermore relates to a method for producing such a hardened cementitious (concrete) composition and a pourable and curable (wet) concrete composition. The invention also relates to a steel reinforced concrete solid having an elevated resistance towards carbonation and a method for producing a steel reinforced concrete solid having an elevated resistance towards carbonation.