Zwitterionic surfactants suitable for enhanced oil recovery
The instant invention relates to surfactants having the following formula (I) wherein: each of R a and R b is a linear or branched, saturated or unsaturated, hydrocarbon chain, each of R c and R d is a alkyl chain having 1 to 10 carbon atoms, each of (E 1 ) and (E 2 ) is a divalent hydrocarbon radical, A is: a group a carboxylate group —COO − (optionally in all or part in the form —COOH); or a sulfonate group —SO 3 − (optionally in all or part in the form —SO 3 H). The invention also relate to the preparation of these surfactants and their use in oil extraction, especially in EOR applications.
1. A surfactant having the formula (I):
wherein:
each of R a and R b , which are identical or different, is a linear or branched, saturated or unsaturated, hydrocarbon chain that is optionally interrupted and/or substituted by at least a monocyclic or polycyclic group,
each of R c and R d , which are identical or different, is a linear or branched, alkyl chain having 1 to 10 carbon atoms,
each of (E 1 ) and (E 2 ) is a divalent hydrocarbon radical linear or branched, not substituted or substituted, optionally carrying a —OH group, and
A is:
a carboxylate group —COO − , optionally in all or part in its protonated form —COOH; or
a sulfonate group —SO 3 − , optionally in all or part in its protonated form —SO 3 H.
2. The surfactant according to claim 1 , which is a betaine of the formula (I-1):
wherein R a , R b , R c , R d , (E 1 ) and (E 2 ) have the meaning given in claim 1 and
wherein:
the amino group —NH— between (E 1 ) and CR a R b is in its protonated form —NH 2 ± —; and/or
the COO − group is in its a protonated form —COOH.
3. The surfactant according to claim 1 , which is a sultaine of the formula (I-2):
wherein R a , R b , R c , R d , (E 1 ) and (E 2 ) have the meaning given in claim 1 and
wherein:
the amino group —NH— between (E 1 ) and CR a R b is in its protonated form —NH 2 ± —; and/or
the SO 3 − group is in its a protonated form —SO 3 H.
4. The surfactant according to claim 1 , wherein R a and R b are linear groups.
5. The surfactant according to claim 4 , wherein R a and R b are each:
a linear alkyl chain having 1 to 24 carbon atoms; or
a linear alkenyl chain having 1 to 20 carbon atoms and having one or more unsaturations.
6. The surfactant of claim 1 , wherein each of R c and R d , which are identical or different, is a linear or branched, alkyl chain having 1 to 4 carbon atoms.
7. The surfactant of claim 1 , wherein each of (E 1 ) and (E 2 ) is an alkanediyl radical of formula —(CH 2 ) n — wherein n=1, 2, 3 or 4, wherein one of the hydrogen may be substituted by a —OH group.
8. The surfactant of claim 1 , wherein (E 2 ) is a divalent hydrocarbon radical linear or branched, not substituted or substituted, carrying a —OH group.
9. The surfactant of claim 1 , wherein (E 2 ) is an alkanediyl radical of formula —(CH 2 ) n — wherein n=1, 2, 3 or 4, wherein one of the hydrogen is substituted by a —OH group.
10. The surfactant according to claim 9 , wherein R a and R b are each a linear alkyl chain having at least 4 carbon atoms.
11. The surfactant according to claim 5 , wherein the sum of the number of carbon in R a and R b is at least 7.
12. An EOR formulation, comprising at least one surfactant of formula (I) according to claim 1 in admixture with other hydrophilic surfactants.
13. A process for preparing the surfactant according to claim 1 , the process comprising:
STEP 1: reacting two acids Ra—COOH and Rb—COOH, wherein Ra and Rb are identical or different, via a Piria decarboxylating ketonization, whereby an internal ketone is obtained having the formula (II):
wherein R a and R b have the meaning given in claim 1 for formula (I);
STEP 2: reacting the internal ketone (II) obtained in step 1 with a diamine of formula H 2 N-(E1)-NR c R d in a reductive amination reaction
whereby a compound of formula (III) is obtained:
wherein R a , R b , R c , R d and (E 1 ) have the meaning given herein-above for formula (I); and
STEP 3: grafting a group -(E2)-A on the amine group —NR c R d of the compound of formula (III) obtained in step (2), wherein (E 2 ) and A have the meaning given herein-above for formula (I), whereby the compound of formula (I) is obtained.
14. The process of claim 13 , wherein step 3 comprises a reaction of the compound (III) with a compound of formula X-(E 2 )-COOH, optionally deprotonated in all or part in the form of a carboxylate, wherein (E 2 ) is a divalent hydrocarbon radical linear or branched, not substituted or substituted, optionally carrying a —OH group, and X is a leaving group.
15. The process of claim 14 , wherein the compound of formula X-(E 2 )-COOH is deprotonated in all or part in the form of a carboxylate.
16. The process of claim 14 , wherein X is Cl.
17. The process of claim 13 , wherein step 3 comprises a reaction of the compound (III) with a compound of formula X-(E 2 )-SO 3 H wherein (E 2 ) is a divalent hydrocarbon radical linear or branched, not substituted or substituted, optionally carrying a —OH group.
18. A method for extracting oil from a subterranean formation, wherein the surfactant of formula (I) according to claim 1 is injected in the subterranean formation.
19. The method of claim 18 , wherein the surfactant of formula (I) is injected in the subterranean formation in admixture with other hydrophilic surfactants.