The invention relates to a process for preparing silica-coated particles of an inorganic expanding agent, the silica-coated particles and their use. The silica-coated particles show a delayed release of the expanding agent particularly in alkaline medium and at elevated temperatures. They are therefore useful in the oil and construction industry.

A system and method for applying a cement composition, including storing a slurry, adding magnesium oxide to the slurry to give a magnesium-oxychloride cement slurry, pumping the magnesium-oxychloride cement slurry into a wellbore, and sealing a loss circulation zone in the wellbore.

A system and method for applying a cement composition, including storing a slurry, adding magnesium oxide to the slurry to give a magnesium-oxychloride cement slurry, pumping the magnesium-oxychloride cement slurry into a wellbore, and sealing a loss circulation zone in the wellbore.

Embodiments provide a method of encapsulating a solid cement additive. The method includes the step of applying a base film-forming monomer to the solid cement additive. The method includes the step of forming a coating layer surrounding the solid cement additive. The coating layer includes the base film-forming monomer. The method includes the step of applying an overlay film-forming monomer to the coating layer surrounding the solid cement additive. The method includes the step of reacting the base film-forming monomer and the overlay film-forming monomer to produce a polymer shell. The solid cement additive includes solid particles useful in cementing applications. The polymer shell includes a crosslinked polymer. The polymer shell surrounds the solid cement additive. The polymer shell has a permeability to water allowing controlled release of the solid cement additive.

Embodiments provide a method of encapsulating a solid cement additive. The method includes the step of applying a base film-forming monomer to the solid cement additive. The method includes the step of forming a coating layer surrounding the solid cement additive. The coating layer includes the base film-forming monomer. The method includes the step of applying an overlay film-forming monomer to the coating layer surrounding the solid cement additive. The method includes the step of reacting the base film-forming monomer and the overlay film-forming monomer to produce a polymer shell. The solid cement additive includes solid particles useful in cementing applications. The polymer shell includes a crosslinked polymer. The polymer shell surrounds the solid cement additive. The polymer shell has a permeability to water allowing controlled release of the solid cement additive.

An additive for mineral binder composition, in particular accelerators for mineral binder compositions, in particular cementitious binder compositions. The accelerator includes 35 to 99.7 w % of at least one mineral filler F with a particle size D50<5 μm, preferably <4 μm, most preferred <3.5 μm, 0.3 to 65 w % of a sodium aluminate SA, and 0 to 45 w % of at least one other inorganic compound I selected from the group consisting of calcium aluminate cements and/or sulfates of alkali or alkaline earth metals. Further, corresponding mineral binder compositions as well as uses and processes, including the acceleration of setting and curing of mineral binder compositions at low temperatures.

Methods to prepare a well cementing slurry include coating particles comprising an expanding agent with a component selected from the group consisting of a phenolic resin, a silica, a calcination product of a polysiloxane oil, and a combination thereof; and combining the coated particles with mix water and hydraulic cement to form a cement slurry for cementing a well.

Methods to prepare a well cementing slurry include coating particles comprising an expanding agent with a component selected from the group consisting of a phenolic resin, a silica, a calcination product of a polysiloxane oil, and a combination thereof; and combining the coated particles with mix water and hydraulic cement to form a cement slurry for cementing a well.

Embodiments provide a method for controlled release of a cement additive for use in a wellbore. The method includes the steps of mixing an aramide capsule with a cement slurry to form an additive-containing slurry, and introducing the additive-containing slurry into the wellbore. The aramide capsule is formed by interfacial polymerization where an aramide polymer forms a semi-permeable membrane encapsulating the cement additive.

Embodiments provide a method for controlled release of a cement additive for use in a wellbore. The method includes the steps of mixing an aramide capsule with a cement slurry to form an additive-containing slurry, and introducing the additive-containing slurry into the wellbore. The aramide capsule is formed by interfacial polymerization where an aramide polymer forms a semi-permeable membrane encapsulating the cement additive.