Method for stimulation of oil and gas wells with phosphate ester surfactants

A method of treating oil- and gas-bearing subterranean formations to improve permeability thereof and increase or restore production of oil or gas comprising introducing into said formation through a producing means in fluid communication with said oil- or gas-bearing subterranean formation, a treating fluid comprising:

• (A) a non-aqueous solution comprising alcohol, aromatic hydrocarbon and from about 5 to about 50 weight percent of an alkyl or aralkyl polyoxyalkylene phosphate ester surfactant having the formulas:
• ##STR2## wherein R.sub.1 represents an alkyl radical having 10 to 18 carbon atoms, R.sub.2 represents an alkyl radical of about 5 to about 27 carbon atoms or cycloalkyl radical and radicals derived from mineral oils containing alkyl, cycloalkyl and mixed alkylcycloalkyl radicals having from about 12 to 27 carbon atoms, R.sub.3 and R.sub.4 represent either hydrogen or alkyl of from about 1 to 22 carbon atoms and the higher alkyls defined by R.sub.1 and cycloalkyls defined by R.sub.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, and 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, alkyl amine and ammonium;
• and thereafter,
• (B) injecting a fluid selected from water and a hydrocarbon into the pore space adjacent to the well bore in amounts sufficient to displace the non-aqueous solution of said phosphate ester out into the formation,
• (C) retaining said non-aqueous solution of said phosphate ester and said hydrocarbon within said formation for a period of not less than 12 hours and
• (D) thereafter, pumping and/or displacing said non-aqueous solution of said phosphate ester and said fluid from said formation into the well bore by injecting water into said formation by an injection means in fluid communication with said oil-bearing or gas-bearing subterranean formation to produce the desired oil or gas through said producing means.