Method and composition for acidizing subterranean formations

Claim 1

A method for acid treating a porous subterranean formation susceptible of attack by an acid and penetrated by a well bore, which method comprises: injecting into said formation via said well bore a gelled acidic composition comprising water; a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides; partially hydrolyzed linear polyacrylamides and partially hydrolyzed linear polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides; partially hydrolyzed crosslinked polyacrylamides and partially hydrolyzed crosslinked polyacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; linear copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and mixtures thereof; an amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition; an amount of a non-oxidizing acid which is sufficient to and capable of reacting with a significant amount of the acid-soluble components of said formation; said polymer, said flavotannin gelling agent, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetation of said composition and in said formation; and maintaining said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 2

A method for acid treating a porous subterranean formation susceptible of attack by an acid and penetrated by a well bore, which method comprises: injecting into said formation via said well bore a gelled acidic composition comprising water; a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides; partially hydrolyzed linear polyacrylamides and partially hydrolyzed linear polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides; partially hydrolyzed crosslinked polyacrylamides and partially hydrolyzed crosslinked polyacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; linear copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and mixtures thereof; an amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition; an amount of a non-oxidizing acid which is sufficient to and capable of reacting with a significant amount of the acid-soluble components of said formation; said polymer, said flavotannin gelling agent, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetation of said composition and in said formation; and maintaining said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 10

A method for acid treating a porous subterranean formation susceptible of attack by an acid and penetrated by a well bore, which method comprises: injecting into said formation via said well bore a gelled acidic composition comprising water; a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides; partially hydrolyzed linear polyacrylamides and partially hydrolyzed linear polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolized to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides; partially hydrolyzed crosslinked polyacrylamides and partially hydrolyzed crosslinked polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; linear copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and mixtures thereof; an amount of a non-oxidizing acid which is sufficient to and capable of reacting with a significant amount of the acid-soluble components of said formation; a small but effective amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition; from about 0.4 to about 1 part by weight of a gelation promoter per part by weight of said gelling agent, said gelation promoter being selected from the group consisting of ammonium chromate, ammonium dichromate, the alkali metal chromates, the alkali metal dichromates, chromium trioxide, sodium permanganate, potassium permanganate, and mixtures thereof; said polymer, said gelling agent, said gelation promoter, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetration of said composition into said formation; and maintaining said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 11

A method for acid treating a porous subterranean formation susceptible of attack by an acid and penetrated by a well bore, which method comprises: injecting into said formation via said well bore a gelled acidic composition comprising water; a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides; partially hydrolyzed linear polyacrylamides and partially hydrolyzed linear polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolized to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides; partially hydrolyzed crosslinked polyacrylamides and partially hydrolyzed crosslinked polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; linear copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and mixtures thereof; an amount of a non-oxidizing acid which is sufficient to and capable of reacting with a significant amount of the acid-soluble components of said formation; a small but effective amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition; from about 0.4 to about 1 part by weight of a gelation promoter per part by weight of said gelling agent, said gelation promoter being selected from the group consisting of ammonium chromate, ammonium dichromate, the alkali metal chromates, the alkali metal dichromates, chromium trioxide, sodium permanganate, potassium permanganate, and mixtures thereof; said polymer, said gelling agent, said gelation promoter, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetration of said composition into said formation; and maintaining said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 23

A method for acid treating a porous subterranean formation susceptible of attack by an acid and penetrated by a well bore, which method comprises: injecting into said formation via said well bore a gelled acidic composition comprising water; a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides; partially hydrolyzed polyacrylamides and partially hydrolyzed linear polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides; partially hydrolyzed crosslinked polyacrylamides and partially hydrolyzed crosslinked polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; linear copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and mixtures thereof, said amount being within the range of from 0.1 to about 1.5 weight percent, based on the total weight of said composition; an amount of a non-oxidizing acid selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, acetic acid, propionic acid, and mixtures thereof, which is sufficient to and capable of reacting with a significant amount of the acid-soluble components of said formation, said amount being within the range of from about 1 to about 60 weight percent based on the total weight of said composition; a small but effective amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition, said amount being within the range of from about 0.4 to about 2 parts by weight per part by weight of said polymer; said polymer, said flavotannin gelling agent, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetration of said composition in said formation; and maintaining said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 24

A method for acid treating a porous subterranean formation susceptible of attack by an acid and penetrated by a well bore, which method comprises: injecting into said formation via said well bore a gelled acidic composition comprising water; a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides; partially hydrolyzed polyacrylamides and partially hydrolyzed linear polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides; partially hydrolyzed crosslinked polyacrylamides and partially hydrolyzed crosslinked polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; linear copolymers of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and mixtures thereof, said amount being within the range of from 0.1 to about 1.5 weight percent, based on the total weight of said composition; an amount of a non-oxidizing acid selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, acetic acid, propionic acid, and mixtures thereof, which is sufficient to and capable of reacting with a significant amount of the acid-soluble components of said formation, said amount being within the range of from about 1 to about 60 weight percent based on the total weight of said composition; a small but effective amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition, said amount being within the range of from about 0.4 to about 2 parts by weight per part by weight of said polymer; said polymer, said flavotannin gelling agent, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetration of said composition in said formation; and maintaining said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 25

A method for acid treating a porous subterranean formation susceptible of attack by an acid and penetrated by a well bore, which method comprises: injecting into said formation via said well bore a gelled acidic composition comprising water; a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides; partially hydrolyzed linear polyacrylamides and partially hydrolyzed linear polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides; partially hydrolyzed crosslinked polyacrylamides and partially hydrolyzed crosslinked polymethacrylamides wherein up to about 25 percent of the carboxamide groups re initially hydrolyzed to carboxyl groups; linear copolymer of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and mixtures thereof, said amount being within the range of from 0.1 to about 1.5 weight percent, based on the total weight of said composition; an amount of a non-oxidizing acid selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, acetic acid, propionic acid, and mixtures thereof, which is sufficient to and capable of reacting with a significant amount of the acid-soluble components of said formation, said amount being within the range of from about 1 to about 60 weight percent based on the total weight of said composition; a small but effective amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition, said amount being within the range of from about 0.4 to about 2 parts by weight per part by weight of said polymer; a small but effective amount of a gelation promoter which is sufficient to promote said gelation, said gelation promoter being selected from the group consisting of ammonium chromate, ammonium dichromate, the alkali metal chromates, the alkali metal dichromates, chromium trioxide, sodium permanganate, potassium permanganate, and mixtures thereof, said amount being within the range of from about 0.4 to about 1 part by weight per part by weight of said gelling agent; said polymer, said gelling agent, said gelation promoter, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetration of said composition into said formation; and maintaining said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 26

A method for acid treating a porous subterranean formation susceptible of attack by an acid and penetrated by a well bore, which method comprises: injecting into said formation via said well bore a gelled acidic composition comprising water; a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides; partially hydrolyzed linear polyacrylamides and partially hydrolyzed linear polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides; partially hydrolyzed crosslinked polyacrylamides and partially hydrolyzed crosslinked polymethacrylamides wherein up to about 25 percent of the carboxamide groups re initially hydrolyzed to carboxyl groups; linear copolymer of acrylamide or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water, and mixtures thereof, said amount being within the range of from 0.1 to about 1.5 weight percent, based on the total weight of said composition; an amount of a non-oxidizing acid selected from the group consisting of hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, acetic acid, propionic acid, and mixtures thereof, which is sufficient to and capable of reacting with a significant amount of the acid-soluble components of said formation, said amount being within the range of from about 1 to about 60 weight percent based on the total weight of said composition; a small but effective amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition, said amount being within the range of from about 0.4 to about 2 parts by weight per part by weight of said polymer; a small but effective amount of a gelation promoter which is sufficient to promote said gelation, said gelation promoter being selected from the group consisting of ammonium chromate, ammonium dichromate, the alkali metal chromates, the alkali metal dichromates, chromium trioxide, sodium permanganate, potassium permanganate, and mixtures thereof, said amount being within the range of from about 0.4 to about 1 part by weight per part by weight of said gelling agent; said polymer, said gelling agent, said gelation promoter, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetration of said composition into said formation; and maintaining said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 42

A method for preparing a gelled acidic composition, suitable for matrix acidizing or fracture-acidizing of a porous subterranean formation susceptible of attack by an acid, said method comprising: a. dispersing in water a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides wherein up to about 25 percent of the carboxamide groups can be initially hydrolyzed to carboxyl groups; linear copolymers of acrylamides or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water; and mixtures thereof; b. then dispersing in said polymer-containing water a small but effective amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition; c. then adding to said water an amount of an acid which is capable of reacting with a significant amount of the acid-soluble soluble components of said formation, and from about 0.4 to about 1 part by weight of a gelation promoter per part by weight of said gelling agent, said gelation promoter being selected from the group consisting of ammonium chromate, ammonium dichromate, the alkali metal chromates, the alkali metal dichromates, chromium trioxide, sodium permanganate, potassium permanganate, and mixtures thereof; said polymer, said gelling agent, said gelation promoter, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetration of said composition into said formation and the maintenance of said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.

Claim 43

A method for preparing a gelled acidic composition, suitable for matrix acidizing or fracture-acidizing of a porous subterranean formation susceptible of attack by an acid, said method comprising: a. dispersing in water a water-thickening amount of a water-dispersible polymer having a molecular weight of at least 500,000 and selected from the group consisting of linear polyacrylamides and polymethacrylamides wherein up to about 25 percent of the carboxamide groups are initially hydrolyzed to carboxyl groups; crosslinked polyacrylamides and crosslinked polymethacrylamides wherein up to about 25 percent of the carboxamide groups can be initially hydrolyzed to carboxyl groups; linear copolymers of acrylamides or methacrylamide with another ethylenically unsaturated monomer copolymerizable therewith, sufficient acrylamide or methacrylamide being present in the monomer mixture to impart said water-dispersible properties to the resulting copolymer when it is mixed with water; and mixtures thereof; b. then dispersing in said polymer-containing water a small but effective amount of a water-dispersible flavotannin gelling agent which is sufficient to cause gelation of an aqueous dispersion of the components of said composition; c. then adding to said water an amount of an acid which is capable of reacting with a significant amount of the acid-soluble soluble components of said formation, and from about 0.4 to about 1 part by weight of a gelation promoter per part by weight of said gelling agent, said gelation promoter being selected from the group consisting of ammonium chromate, ammonium dichromate, the alkali metal chromates, the alkali metal dichromates, chromium trioxide, sodium permanganate, potassium permanganate, and mixtures thereof; said polymer, said gelling agent, said gelation promoter, and said acid, in the amounts used, being sufficiently compatible with each other in an aqueous dispersion thereof to permit said gelation and thus form a said composition having sufficient stability to degeneration by the heat of said formation to permit good penetration of said composition into said formation and the maintenance of said composition in said formation in contact therewith for a period of time usually sufficient for the acid in said composition to react significantly with the acid-soluble components of said formation and stimulate the production of fluids therefrom.