Alkyl alkoxylated carboxylate salts as steam foam additives for heavy oil recovery
Recovering heavy oil from a subterraneous formation penetrated by at least one injection well and one production well, by injecting into the injection well a mixture of steam and an alkyl alkoxylated carboxylate salt, increasing the apparent viscosity of the steam while at the same time lowering the steam mobility, and recovering oil from the subterranean formation.
1. A method for heavy oil recovery from a subterranean formation that is penetrated by at least one injection well and one production well, comprising:
i) injecting into an injection well a mixture of steam and a surfactant, said surfactant comprising an alkyl alkoxylated carboxylate salt, wherein said alkyl alkoxylated carboxylate salt has a molecular structure as shown in [1],
wherein
R is a linear, or branched, or mixture of linear and branched alkyl group, having from 16 to 36 carbon atoms,
AO′ is a propoxy (PO) group,
AO″ is an ethoxy (EO) or a PO group,
R′ is a methylene or an ethylene or a propylene group,
n=1-15,
m=0-15,
m+n≤20,
provided, in the case where both PO and EO groups are present, the PO/EO molar ratio is less than 1,
provided that in the case where R includes branched alkyl groups, the branched molecules have an average number of 0.3 to 3.5 branches per molecule, and at least one branch is in the 2-alkyl position,
and
M′ is an alkali metal ion, an alkanol amine ion, an alkyl amine ion, or an ammonium ion,
ii) increasing the apparent viscosity of the steam, and at the same time lowering the steam mobility, and
iii) recovering oil from the subterranean formation.
2. The method of claim 1 , wherein R is a mixture of linear and branched alkyl groups.
3. The method of claim 1 , wherein R is a branched alkyl group.
4. The method claim 1 , wherein both PO and EO are present.
5. The method of claim 1 wherein R is 20 to 26 carbon atoms.
6. The method of claim 1 wherein M + is an alkali metal ion, an alkanol amine ion, or an ammonium ion.