Branched alkylpolyethoxypropane sulfonates and their use in enhanced oil recovery

Claim 2

A compound having the formula RO(C.sub.2 H.sub.4 O).sub.x CH.sub.2 CH.sub.2 CH.sub.2 SO.sub.3 Na in which R is a branched aliphatic radical containing 10 to 30 carbon atoms, in which R is the alkyl group in which R 2 contains 2 to 10 carbon atoms, R 3 contains 6 to 26 carbon atoms and x is 2 to 6.

Claim 3

The compound of claim 1 in which the branching in R is such that said compound has its minimum oil/water interfacial tension in brine of less than 30 percent, the minimum interfacial tension being a factor of 0.5 or less than that of the corresponding compound in which R is unbranched, measured at the same percent salinity.

Claim 4

A compound of claim 1 in which R 3 contains 8 to 12 carbon atoms and R 2 contains 4 to 6 carbon atoms.

Claim 5

A compound of claim 1 in which R is alkyl of the formula ##STR7## in which R 3 contains 6 to 26 carbon atoms and R 2 contains 2 to 10 carbon atoms.

Claim 6

A process for recovering oil from a subterranean oil reservoir having one or more production wells and one or more injection wells in contact with said oil reservoir, comprising contacting said oil reservoir with a high salinity aqueous medium which includes as the sole surfactant, a compound having the formula RO(C.sub.2 H.sub.4 O).sub.x CH.sub.2 CH.sub.2 CH.sub.2 SO.sub.3 Na in which R is a branched aliphatic radical containing 10 to 30 carbon atoms, in which R is the alkyl group ##STR8## in which R 1 contains 7 to 26 carbon atoms, R 2 contains 2 to 10 carbon atoms, R 3 contains 6 to 26 carbon atoms and x is 2 to 6, at a concentration effective to increase oil production from said production well during secondary water flooding or to recover residual tertiary oil when the oil reservoir has been previously flooded.

Claim 7

A process for recovering oil from a subterranean oil reservoir having one or more production wells and one or more injection wells in contact with said oil reservoir, comprising contacting said oil reservoir with a high salinity aqueous medium which includes as the sole surfactant, a compound having the formula RO(C.sub.2 H.sub.4 O).sub.x CH.sub.2 CH.sub.2 CH.sub.2 SO.sub.3 Na in which R is a branched aliphatic radical containing 10 to 30 carbon atoms, in which R is the alkyl group ##STR8## in which R 1 contains 7 to 26 carbon atoms, R 2 contains 2 to 10 carbon atoms, R 3 contains 6 to 26 carbon atoms and x is 2 to 6, at a concentration effective to increase oil production from said production well during secondary water flooding or to recover residual tertiary oil when the oil reservoir has been previously flooded.

Claim 8

The process of claim 5 wherein said oil reservoir has a salinity of from about 4 to about 30% brine.

Claim 9

The process of claim 5 in which said aqueous medium includes a sacrificial compound in an amount effective to substantially reduce adsorption of the surfactant and thereby further increase oil production from said production well.

Claim 10

The process of claim 5 wherein the sacrificial compound is lignin sulfonate.

Claim 11

The process of claim 5 wherein the amount of lignin sulfonate is from about 0.75 to about 3 weight percent.