Disclosed is a novel aqueous surfactant-containing fluid suitable for use in surfactant flooding oil recovery processes, and an oil recovery process using the fluid. The fluid contains petroleum sulfonates alone or in combination with solubilizing co-surfactants such as ethoxylated alkyl or alkylaryl compounds, alkyl or alkylaryl polyethoxy sulfates, or alkyl or alkylaryl polyethoxy sulfonates. The petroleum sulfonate is a mixture of petroleum sulfonates of varying equivalent weights ranging from 250 to 700, with an average equivalent weight between 325 and 425 and preferably between 350 and 400. Additionally, the distribution of equivalent weights is relatively uniform, with from 40 to 70 percent being less than 400 and from 60 to 30 percent of the petroleum sulfonates having equivalent weights being 400 or greater; and preferably from 15 to 35 percent of the petroleum sulfonates having equivalent weights less than 350, and 30 to 50 percent having equivalent weights from 350 to less than 500 and from 10 to 40 percent of the petroleum sulfonates having equivalent weights of 500 and above. The especially preferred embodiment employs a mixture of petroleum sulfonates in which 5 to 15 percent have equivalent weights less than 300, from 25 to 50 percent have equivalent weights the range of from about 300 to less than 400, from 15 to 25 percent fall in the range of from about 400 to less than 500 and from 5 to 20 percent have equivalent weights greater than 500.
The recovery of residual oil which is found in subterranean reservoirs may be accomplished by utilizing an aqueous surfactant slug to reduce the interfacial tension between oil and water. An effective surfactant slug which may be used will comprise a mixture of: (1) from about 1 to about 10% of a sulfonate of a mixture of mono- and dialkyl-substituted aromatic hydrocarbon which has been obtained by the alkylation of an aromatic hydrocarbon with an olefinic hydrocarbon in the presence of a hydrogen fluoride catalyst; (2) a lower alkyl alcohol which possesses from about 3 to about 6 carbon atoms; and (3) a nonionic cosurfactant comprising an ethoxylated n-alcohol which possesses from about 12 to about 15 carbon atoms.
The recovery of residual oil which is found in subterranean reservoirs may be accomplished by utilizing an aqueous surfactant slug to reduce the interfacial tension between the oil and water. A surfactant slug which may be used will comprise a mixture of a neutralized sulfonate derivative from powdered coal, a lower alkyl alcohol which possesses from about 3 to about 6 carbon atoms and a non-ionic surfactant comprising an ethoxylated n-alcohol possessing from about 12 to about 15 carbon atoms. The surfactant slug will possess relatively low interfacial tension which may be in the range of from below 10.sup.-3 dynes per cm.
An aqueous mobility control solution for tertiary oil recovery from saline oil fields comprises from about 200 to 2000 ppm xanthan biopolymer in the form of clean, unreconstituted fermentation broth and from about 20 to 200 ppm of a selected water-soluble polyglycol-based surfactant. A process for tertiary oil recovery which comprises the injection of the mobility control solution into saline oil-bearing subterranian formations is also disclosed.
A method for improving the mobility and pipeline transport of a viscous crude oil by forming an oil-in-water emulsion with said oil and from 10 to 80% by weight of water in the presence of 100 to 1500 parts by weight of a surfactant blend per million parts by weight of said emulsion, said blend comprising from 15 to 85 parts by weight of an anionic or amphoteric surfactant (A) selected from those of the formulae Ar(OCH.sub.2 CH.sub.2).sub.n OSO.sub.3 H, ##STR1## a sodium and ammonium salt thereof, and from 85 to 15 parts by weight of a nonionic surfactant selected from (B) of the formula Ar(OCH.sub.2 CH.sub.2).sub.p OH or (C) of the formula ##STR2## the latter having an HLB value of from 10 to 20; where Ar is octylphenyl or nonylphenyl, n is 2 to 10, p is 10 to 100, a is 10 to 40, b is 15 to 55, c is 10 to 40, R.sup.1 is C.sub.8 to C.sub.18 alkyl and R.sup.2 is C.sub.12 to C.sub.18 alkyl; and said emulsion.
Novel branched alkylpolyethoxypropane sulfonate surfactants which have low interfacial tension at high salinity, and their use in enhanced oil recovery are disclosed. The surfactants have the formula in which R is a branched aliphatic radical of 10 to 30 carbon atoms, and x is 2 to 6.
