Abstract: A composition in the form of an emulsion having: (i) a continuous oil phase comprising: (a) an oil; (b) an emulsifier; and (ii) an internal aqueous phase comprising: (a) water; (b) acid such that the aqueous phase has an initial pH of less than about 2; (c) a viscosity-increasing agent; and (d) a crosslinker, wherein the crosslinker is selected or controlled to crosslink the viscosity-increasing agent at a pH range somewhere in a range of about 1.5 to about 6.5 and that is at least higher than the initial pH of the aqueous phase. A method of acidizing a treatment zone of a subterranean formation in a well includes the steps of: (A) forming a treatment fluid comprising such a composition; and (B) introducing the treatment fluid into a well.

Abstract: A composition in the form of an emulsion having: (i) a continuous oil phase comprising: (a) an oil; (b) an emulsifier; and (ii) an internal aqueous phase comprising: (a) water; (b) acid such that the aqueous phase has an initial pH of less than about 2; (c) a viscosity-increasing agent; and (d) a crosslinker, wherein the crosslinker is selected or controlled to crosslink the viscosity-increasing agent at a pH range somewhere in a range of about 1.5 to about 6.5 and that is at least higher than the initial pH of the aqueous phase. A method of acidizing a treatment zone of a subterranean formation in a well includes the steps of: (A) forming a treatment fluid comprising such a composition; and (B) introducing the treatment fluid into a well.

Abstract: A composition in the form of an emulsion having: (i) a continuous oil phase comprising: (a) an oil; (b) an emulsifier; and (c) a particulate comprising an oxide selected from the group consisting of metal oxides, metalloid oxides, and any combination thereof, wherein the particulate is hydrophobically modified, would not dissolve in oil or 28% hydrochloric acid, and has a surface area in the range of 700 m2/g to 30 m2/g; and (ii) an internal aqueous phase comprising water having a pH of less than zero. A method of acidizing a treatment zone of a subterranean formation in a well includes the steps of: (A) forming a treatment fluid comprising such a composition; and (B) introducing the treatment fluid into a well, wherein the design temperature is at least 275° F. Preferably, the particulate is hydrophobically modified silica.

Abstract: An emulsion including: (a) an external oil phase, wherein the oil phase has a viscosity of less than 200 cP; (b) an internal water phase adjacent the external phase, wherein the internal water phase has a pH in the range of 5 to 9; (c) an emulsifier having a hydrophilic-lipophilic balance in the range of 3 to 7 on the Davies scale; and (d) a Bronsted-Lowry base having a pKb(1) less than 12, wherein the base is encapsulated with an encapsulated breaker composition comprising: an encapsulant that comprises an ether cellulose. A method of treating a well includes the steps of: forming a treatment fluid including the emulsion; and introducing the treatment fluid into the well. In a preferred embodiment, the emulsion has a viscosity greater than 200 cP.