A method for plugging and sealing subsurface formations using alkaline nanosilica dispersion and a delayed activation chemistry is disclosed. In accordance with one embodiment of the present disclosure, the method includes introducing a mixture with a first pH into the subsurface formation. The mixture comprises an aqueous solution, an alkaline nanosilica dispersion and a water-soluble hydrolyzable compound. The method further includes allowing the water-soluble hydrolyzable compound to hydrolyze in the subsurface formation to form an acid at 70 C. or greater, thereby acidizing the mixture to a reduced second pH and causing the alkaline nanosilica dispersion to gel into a solid and seal the subsurface formation. A composition for sealing a subsurface formation is also disclosed. The composition includes an aqueous mixture including water, an alkaline nanosilica dispersion, and a water-soluble hydrolyzable compound.

A method for plugging and sealing subsurface formations using alkaline nanosilica dispersion and a delayed activation chemistry is disclosed. In accordance with one embodiment of the present disclosure, the method includes introducing a mixture with a first pH into the subsurface formation. The mixture comprises an aqueous solution, an alkaline nanosilica dispersion and a water-soluble hydrolyzable compound. The method further includes allowing the water-soluble hydrolyzable compound to hydrolyze in the subsurface formation to form an acid at 70 C. or greater, thereby acidizing the mixture to a reduced second pH and causing the alkaline nanosilica dispersion to gel into a solid and seal the subsurface formation. A composition for sealing a subsurface formation is also disclosed. The composition includes an aqueous mixture including water, an alkaline nanosilica dispersion, and a water-soluble hydrolyzable compound.

A composition of a cement additive material to improve durability of cementitious structures, was disclosed. The cement additive composition includes an admixture of one or more of divalent magnesium metal silicates with capacity to act as a latent hydraulic binder in said composition activated by a hydration process under aqueous conditions, and in particular the divalent metal silicate is magnesium-dominated silicate, preferably comprising mineral groups of olivines, orthopyroxenes, amphiboles, and serpentines or mixtures thereof. The composition also includes chloride ions or brine.

A composition of a cement additive material to improve durability of cementitious structures, was disclosed. The cement additive composition includes an admixture of one or more of divalent magnesium metal silicates with capacity to act as a latent hydraulic binder in said composition activated by a hydration process under aqueous conditions, and in particular the divalent metal silicate is magnesium-dominated silicate, preferably comprising mineral groups of olivines, orthopyroxenes, amphiboles, and serpentines or mixtures thereof. The composition also includes chloride ions or brine.

Various embodiments disclosed relate to compatibilized resin-cement composite compositions and methods of using the same. In various embodiments, the present invention provides a method of treating a subterranean formation that includes placing in the subterranean formation a resin-cement composite composition. The resin-cement composite composition includes a resin, a cement, and a substituted or unsubstituted poly(alkylamine) compatibilizer.

Various embodiments disclosed relate to compatibilized resin-cement composite compositions and methods of using the same. In various embodiments, the present invention provides a method of treating a subterranean formation that includes placing in the subterranean formation a resin-cement composite composition. The resin-cement composite composition includes a resin, a cement, and a substituted or unsubstituted poly(alkylamine) compatibilizer.

Some embodiments of the present invention comprise a method of cementing comprising: placing a settable composition into a well bore, the settable composition comprising RFA, hydraulic cement, and water; and allowing the settable composition to set. Other embodiments comprise a method of cementing comprising: placing a settable composition into a well bore, the settable composition comprising RFA, calcium hydroxide (lime), and water; and allowing the settable composition to set. Other embodiments comprise a settable composition comprising: RFA, hydraulic cement, calcium hydroxide, natural pozzolan and water; and allowing the composition to set. Other embodiments comprise a settable composition comprising RFA and any combination of hydraulic cement, calcium hydroxide, slag, fly ash, and natural or other pozzolan.

Some embodiments of the present invention comprise a method of cementing comprising: placing a settable composition into a well bore, the settable composition comprising RFA, hydraulic cement, and water; and allowing the settable composition to set. Other embodiments comprise a method of cementing comprising: placing a settable composition into a well bore, the settable composition comprising RFA, calcium hydroxide (lime), and water; and allowing the settable composition to set. Other embodiments comprise a settable composition comprising: RFA, hydraulic cement, calcium hydroxide, natural pozzolan and water; and allowing the composition to set. Other embodiments comprise a settable composition comprising RFA and any combination of hydraulic cement, calcium hydroxide, slag, fly ash, and natural or other pozzolan.

Migration of formation solids in a wellbore is restrained by feeding a slurry, comprising water, a viscosifier, and a concentration of cement clinker particles, into the wellbore, and hydrating the clinker particles in the wellbore. The clinker particles are kept in suspension during the hydrating, and upon completion of the hydrating the hydrated clinker particles form a hardened cement consisting of a permeable structure of interconnected hydrated clinker particles. A layer of degradable lost circulation material (LCM) may be employed to separate the slurry with clinker particles from the formation surrounding the wellbore during hydrating of the clinker particles.

Migration of formation solids in a wellbore is restrained by feeding a slurry, comprising water, a viscosifier, and a concentration of cement clinker particles, into the wellbore, and hydrating the clinker particles in the wellbore. The clinker particles are kept in suspension during the hydrating, and upon completion of the hydrating the hydrated clinker particles form a hardened cement consisting of a permeable structure of interconnected hydrated clinker particles. A layer of degradable lost circulation material (LCM) may be employed to separate the slurry with clinker particles from the formation surrounding the wellbore during hydrating of the clinker particles.