A liquid concentrate for use in a well that penetrates a subterranean formation comprising: a base liquid; and a strength retrogression additive, wherein the strength retrogression additive consists of particles of silicon dioxide containing crystalline regions, wherein the liquid concentrate has an activity of at least 40%. A method of cementing in a subterranean formation comprising: providing the liquid concentrate; forming a cement composition by adding a predetermined volume of the liquid concentrate to at least cement and water; and introducing the cement composition into the subterranean formation

A liquid concentrate for use in a well that penetrates a subterranean formation comprising: a base liquid; and a strength retrogression additive, wherein the strength retrogression additive consists of particles of silicon dioxide containing crystalline regions, wherein the liquid concentrate has an activity of at least 40%. A method of cementing in a subterranean formation comprising: providing the liquid concentrate; forming a cement composition by adding a predetermined volume of the liquid concentrate to at least cement and water; and introducing the cement composition into the subterranean formation

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 cement composition for use in a well that penetrates a subterranean formation comprising: cement; water; an environmentally-friendly curable resin having two or more epoxy functional groups; and a curing agent that causes the curable resin to cure when in contact with the curing agent. A method of cementing in a subterranean formation comprising: introducing the cement composition into the subterranean formation; and allowing the cement composition to set after introduction.

A cement composition for use in a well that penetrates a subterranean formation comprising: cement; water; an environmentally-friendly curable resin having two or more epoxy functional groups; and a curing agent that causes the curable resin to cure when in contact with the curing agent. A method of cementing in a subterranean formation comprising: introducing the cement composition into the subterranean formation; and allowing the cement composition to set after introduction.

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

A cement composition for use in a well that penetrates a subterranean formation comprising: cement; and water, wherein the water is in a concentration in the range of about 220% to about 800% by weight of the cement, wherein the cement composition is acid soluble. A method of treating a subterranean formation comprising: introducing the cement composition into the subterranean formation; allowing the composition to set; and contacting the set cement composition with an acid.

A cement composition for use in a well that penetrates a subterranean formation comprising: cement; and water, wherein the water is in a concentration in the range of about 220% to about 800% by weight of the cement, wherein the cement composition is acid soluble. A method of treating a subterranean formation comprising: introducing the cement composition into the subterranean formation; allowing the composition to set; and contacting the set cement composition with an acid.