The purpose for the invention is to develop a low-viscosity sealant that can be placed into the well fractures easily while providing long-term robust wellbore sealing. Nanoparticles like nanosilica particles are proposed and used to seal the fractures and keep the wellbore integrity. Application of nanosilica particles is beneficial as it has a low viscosity and requires low pressure to inject into fractures.

A method for controlling loss circulation in a subterranean formation. The method includes circulating in a wellbore a nanosilica drilling fluid having a pH in a range of from about 8 to about 11 and a gel pH of less than 8, where the nanosilica drilling fluid includes an aqueous-based drilling mud and an alkaline nanosilica dispersion. The method also includes introducing into the nanosilica drilling fluid an amount of a chemical activator sufficient to produce a convertible drilling mud where the chemical activator is an acid and the pH of the convertible drilling mud is less than the gel pH. The method also includes allowing the convertible drilling mud to convert into the solid gel lost circulation material. A convertible drilling mud operable to convert into a solid gel lost circulation material is also provided.

A method for controlling loss circulation in a subterranean formation. The method includes circulating in a wellbore a nanosilica drilling fluid having a pH in a range of from about 8 to about 11 and a gel pH of less than 8, where the nanosilica drilling fluid includes an aqueous-based drilling mud and an alkaline nanosilica dispersion. The method also includes introducing into the nanosilica drilling fluid an amount of a chemical activator sufficient to produce a convertible drilling mud where the chemical activator is an acid and the pH of the convertible drilling mud is less than the gel pH. The method also includes allowing the convertible drilling mud to convert into the solid gel lost circulation material. A convertible drilling mud operable to convert into a solid gel lost circulation material is also provided.

Provided are aqueous resin solutions having unique rheologies and products incorporating the same. The water-based materials provided herein are thermo-thickening, and the materials increase dramatically in viscosity (at least 100 times) in a desired temperature range increase (20 C to <100 C) at ambient pressure. Suitable resins comprising a hydrophobic group and a hydrophilic group may be selected from an epoxy resin, a phenol-formaldehyde resin, a polyurethane resin, an acrylic resin, a polyester resin, an acrylic-urethane resin, a melamine resin, a melamine-formaldehyde resin, an amino resin, and combinations thereof. A specific epoxy functional resin/polymer suitable for the resin solutions are prepared by reacting (A) an epoxy pre-polymer of (1) one or more polyols and (2) one or more epoxy functional materials with (B) a di- or polyamine, thereby forming the aqueous thermo-thickening resin solution. The resin solutions are substantially free of cross-linking agents.

Provided are aqueous resin solutions having unique rheologies and products incorporating the same. The water-based materials provided herein are thermo-thickening, and the materials increase dramatically in viscosity (at least 100 times) in a desired temperature range increase (20 C to <100 C) at ambient pressure. Suitable resins comprising a hydrophobic group and a hydrophilic group may be selected from an epoxy resin, a phenol-formaldehyde resin, a polyurethane resin, an acrylic resin, a polyester resin, an acrylic-urethane resin, a melamine resin, a melamine-formaldehyde resin, an amino resin, and combinations thereof. A specific epoxy functional resin/polymer suitable for the resin solutions are prepared by reacting (A) an epoxy pre-polymer of (1) one or more polyols and (2) one or more epoxy functional materials with (B) a di- or polyamine, thereby forming the aqueous thermo-thickening resin solution. The resin solutions are substantially free of cross-linking agents.

Wellbore synthesis techniques are disclosed suitable for use in geothermal applications. Embodiments are provided where open hole drilled wellbores are sealed while drilling to form an impervious layer at the wellbore/formation interface. The techniques may be chemical, thermal, mechanical, biological and are fully intended to irreversibly damage the formation in terms of the permeability thereof. With the permeability negated, the wellbore may be used to create a closed loop surface to surface geothermal well operable in the absence of well casing for maximizing thermal transfer to a circulating working fluid. Formulations for the working and drilling fluids are disclosed.

Wellbore synthesis techniques are disclosed suitable for use in geothermal applications. Embodiments are provided where open hole drilled wellbores are sealed while drilling to form an impervious layer at the wellbore/formation interface. The techniques may be chemical, thermal, mechanical, biological and are fully intended to irreversibly damage the formation in terms of the permeability thereof. With the permeability negated, the wellbore may be used to create a closed loop surface to surface geothermal well operable in the absence of well casing for maximizing thermal transfer to a circulating working fluid. Formulations for the working and drilling fluids are disclosed.

A process of preparing a concrete mixture includes the following steps: (a) providing a nano-sized non-sand silica and water; (b) mixing the non-sand silica with the water to form a silica-water mixture; (c) mixing an acid into the silica-water mixture to form a treated water; (d) mixing Portland cement and the treated water for a time sufficient to wet the Portland cement with the treated water to form a Portland/treated-water mixture; (e) mixing aggregate and the Portland-treated-water mixture to form an uncured concrete; and (f) allowing the uncured concrete to cure to form a cured concrete.

A process of preparing a concrete mixture includes the following steps: (a) providing a nano-sized non-sand silica and water; (b) mixing the non-sand silica with the water to form a silica-water mixture; (c) mixing an acid into the silica-water mixture to form a treated water; (d) mixing Portland cement and the treated water for a time sufficient to wet the Portland cement with the treated water to form a Portland/treated-water mixture; (e) mixing aggregate and the Portland-treated-water mixture to form an uncured concrete; and (f) allowing the uncured concrete to cure to form a cured concrete.

Wellbore synthesis techniques are disclosed suitable for use in geothermal applications. Embodiments are provided where open hole drilled wellbores are sealed while drilling to form an impervious layer at the wellbore/formation interface. The techniques may be chemical, thermal, mechanical, biological and are fully intended to irreversibly damage the formation in terms of the permeability thereof. With the permeability negated, the wellbore may be used to create a closed loop surface to surface geothermal well operable in the absence of well casing for maximizing thermal transfer to a circulating working fluid. Formulations for the working and drilling fluids are disclosed.