Stimulation of gas wells with phosphate ester surfactants

Claim 1

A method of treating gas-bearing subterranean formations to improve permeability thereof and increase or restore production of gas comprising introducing into said formation through a producing means in fluid communication with said gas-bearing subterranean formation, a treating fluid comprising: (A) an aqueous solution of about 5 to about 50 weight percent of an alkyl or aralkyl polyoxyalkylene phosphate ester surfactant having the formula: ##STR2## wherein R 1 represents an alkyl radical containing from about 10 to 18 carbon atoms, R 2 represents an alkyl radical of about 5 to about 27 carbon atoms or a cycloalkyl radical and radicals derived from mineral oils containing alkyl, cycloalkyl and mixed alkylcycloalkyl radicals having from about 12 to 27 carbon atoms, R 3 and R 4 represent either hydrogen or alkyl of from about 1 to 22 carbon atoms and the higher alkyls defined by R 1 and cycloalkyls defined by R 2 or radicals derived from mineral oils; A represents the residue of ethylene oxide, ethylene oxide and tetrahydrofuran, or mixed lower alkylene oxides selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide, alone or including tetrahydrofuran, wherein the total molecular weight of said ester is about 500 to about 1500, and wherein A can be heteric or block in molecular configuration; n represents the degree of oxyalkylation; x and y are 1 or 2, the sum of x and y is 3 and z is an integer of 0 to 5; X is hydrogen or a monovalent cation selected from at least one of the group consisting of an alkali metal, and ammonium; and thereafter, (B) injecting water into the pore space adjacent to the well bore in amounts sufficient to displace the aqueous solution of said phosphate ester out into the formation, (C) retaining said aqueous solution of said phosphate ester and water within said formation for a period of not less than 24 hours and (D) thereafter, pumping and/or displacing said aqueous solution of said phosphate ester and said water from said formation into the well bore by injecting water into said formation by an injection means in fluid communication with said gas-bearing subterranean formation to produce the desired gas through said producing means.

Claim 2

A method of treating gas-bearing subterranean formations to improve permeability thereof and increase or restore production of gas comprising introducing into said formation through a producing means in fluid communication with said gas-bearing subterranean formation, a treating fluid comprising: (A) an aqueous solution of about 5 to about 50 weight percent of an alkyl or aralkyl polyoxyalkylene phosphate ester surfactant having the formula: ##STR2## wherein R 1 represents an alkyl radical containing from about 10 to 18 carbon atoms, R 2 represents an alkyl radical of about 5 to about 27 carbon atoms or a cycloalkyl radical and radicals derived from mineral oils containing alkyl, cycloalkyl and mixed alkylcycloalkyl radicals having from about 12 to 27 carbon atoms, R 3 and R 4 represent either hydrogen or alkyl of from about 1 to 22 carbon atoms and the higher alkyls defined by R 1 and cycloalkyls defined by R 2 or radicals derived from mineral oils; A represents the residue of ethylene oxide, ethylene oxide and tetrahydrofuran, or mixed lower alkylene oxides selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide, alone or including tetrahydrofuran, wherein the total molecular weight of said ester is about 500 to about 1500, and wherein A can be heteric or block in molecular configuration; n represents the degree of oxyalkylation; x and y are 1 or 2, the sum of x and y is 3 and z is an integer of 0 to 5; X is hydrogen or a monovalent cation selected from at least one of the group consisting of an alkali metal, and ammonium; and thereafter, (B) injecting water into the pore space adjacent to the well bore in amounts sufficient to displace the aqueous solution of said phosphate ester out into the formation, (C) retaining said aqueous solution of said phosphate ester and water within said formation for a period of not less than 24 hours and (D) thereafter, pumping and/or displacing said aqueous solution of said phosphate ester and said water from said formation into the well bore by injecting water into said formation by an injection means in fluid communication with said gas-bearing subterranean formation to produce the desired gas through said producing means.