Acid composition and method for acid treating geological formations

Claim 1

An acid composition comprising a substantially anhydrous liquid mixture containing about 60 to 95 weight percent of polyphosphoric acid having about 40 to 86 percent of the total P 2 O 5 present as polymeric P 2 O 5 , about 2 to 8 weight percent of hydrofluoric acid, and wherein the H 2 O/P 2 O 5 mole ratio of the overall acid mixture is less than 3.4.

Claim 10

A method for increasing the permeability of a silicone subterranean geological formation penetrated by a well bore which comprises introducing through said well bore and into the formation surrounding said well bore, at a pressure below the fracture pressure of the formation, a substantially anhydrous liquid acid composition comprising a mixture of about 60 to 95 weight percent of polyphosphoric acid, said polyphosphoric acid containing about 40 to 86 weight percent of the total P 2 O 5 present as polymeric P 2 O 5 ; about 2 to 8 weight percent of hydrofluoric acid; about 2 to 40 weight percent of a catalyst selected from the group consisting of (a) strong mineral acids selected from the group consisting of sulfuric, nitric and hydrochloric acids and mixtures thereof; (b) unsubstituted aromatic and unsubstituted aliphatic monocarboxylic, dicarboxylic and tricarboxylic acids having from 1 to about 6 carbon atoms and chlorine substituted derivatives thereof; and (c) oxidizing agents selected from the group consisting of organic and inorganic peroxides, a compound containing permanganate ion, the hypochlorite ion, the perchlorate ion or the chlorate ion, and a compound containing the chromium ion having a valence of 6 and wherein the H 2 O/P 2 O 5 mole ratio of the overall acid mixture is less than 3.4.

Claim 11

A method for increasing the permeability of a silicone subterranean geological formation penetrated by a well bore which comprises introducing through said well bore and into the formation surrounding said well bore, at a pressure below the fracture pressure of the formation, a substantially anhydrous liquid acid composition comprising a mixture of about 60 to 95 weight percent of polyphosphoric acid, said polyphosphoric acid containing about 40 to 86 weight percent of the total P 2 O 5 present as polymeric P 2 O 5 ; about 2 to 8 weight percent of hydrofluoric acid; about 2 to 40 weight percent of a catalyst selected from the group consisting of (a) strong mineral acids selected from the group consisting of sulfuric, nitric and hydrochloric acids and mixtures thereof; (b) unsubstituted aromatic and unsubstituted aliphatic monocarboxylic, dicarboxylic and tricarboxylic acids having from 1 to about 6 carbon atoms and chlorine substituted derivatives thereof; and (c) oxidizing agents selected from the group consisting of organic and inorganic peroxides, a compound containing permanganate ion, the hypochlorite ion, the perchlorate ion or the chlorate ion, and a compound containing the chromium ion having a valence of 6 and wherein the H 2 O/P 2 O 5 mole ratio of the overall acid mixture is less than 3.4.

Claim 16

A method for increasing the permeability of a siliceous subterranean geological formation penetrated by a well bore which comprises hydraulically fracturing said formation by introducing thereinto at a pressure sufficient to fracture said formation a highly viscous substantially anhydrous liquid acid composition comprising a mixture of 60 to 95 weight percent of polyphosphoric acid, said polyphosphoric acid containing about 40 to 86 weight percent of the total P 2 O 5 present as polymeric P 2 O 5 ; about 2 to 8 weight percent of hydrofluoric acid; about 2 to 40 weight percent of a catalyst selected from the group consisting of (a) strong mineral acids selected from the group consisting of a sulfuric, nitric and hydrochloric acids and mixtures thereof; (b) unsubstituted aromatic and unsubstituted aliphatic monocarboxylic, dicarboxylic and tricarboxylic acids having from 1 to about 6 carbon atoms and chlorine substituted derivatives thereof; and (c) oxidizing agents selected from the group consisting of organic and inorganic peroxides, a compound containing permanganate ion, the hypochlorite ion, the perchlorate ion or the chlorate ion, and a compound containing the chromium ion having a valence of 6 and wherein the H 2 O/P 2 O 5 mole ratio of the overall acid mixture is less than 3.4.

Claim 17

A method for increasing the permeability of a siliceous subterranean geological formation penetrated by a well bore which comprises hydraulically fracturing said formation by introducing thereinto at a pressure sufficient to fracture said formation a highly viscous substantially anhydrous liquid acid composition comprising a mixture of 60 to 95 weight percent of polyphosphoric acid, said polyphosphoric acid containing about 40 to 86 weight percent of the total P 2 O 5 present as polymeric P 2 O 5 ; about 2 to 8 weight percent of hydrofluoric acid; about 2 to 40 weight percent of a catalyst selected from the group consisting of (a) strong mineral acids selected from the group consisting of a sulfuric, nitric and hydrochloric acids and mixtures thereof; (b) unsubstituted aromatic and unsubstituted aliphatic monocarboxylic, dicarboxylic and tricarboxylic acids having from 1 to about 6 carbon atoms and chlorine substituted derivatives thereof; and (c) oxidizing agents selected from the group consisting of organic and inorganic peroxides, a compound containing permanganate ion, the hypochlorite ion, the perchlorate ion or the chlorate ion, and a compound containing the chromium ion having a valence of 6 and wherein the H 2 O/P 2 O 5 mole ratio of the overall acid mixture is less than 3.4.