Sulphonated internal ketone-based formulations for assisted recovery of oil
The present invention relates to compositions for enhanced oil recovery, comprising: (A) internal ketones sulfonated alpha to the ketone group; and (B) unsulfonated internal ketones, with a molar ratio B/(A+B) greater than or equal to the limiting molar concentration of unsulfonated ketones from which a stabilization is observed in the reduction in mobility when the mixture of said ketones is injected into a porous medium.
1. A composition suitable for enhanced oil recovery, comprising:
(A) internal ketones sulfonated alpha to the ketone group; and
(B) unsulfonated internal ketones,
with a molar ratio B/(A+B), corresponding to the molar concentration of unsulfonated ketones, ranging between 10% and 50%.
2. The composition as claimed in claim 1 , wherein the compounds A comprise a mixture of at least one monosulfonate and at least one disulfonate, conforming respectively to the formulae (1) and (2) below:
where:
each of R 1 , R 3 and R 5 , which are identical or different, is independently a hydrogen or a linear or branched alkyl chain having from 1 to 20 carbon atoms;
each of R 2 and R 4 , which are identical or different, is independently a linear alkyl chain or having from 4 to 24 carbon atoms, it being possible for said alkyl chain to comprise cycloaliphatic groups; and
X is H; or else —SO 3 X is a sulfonate salt formed with 1/n mol of a cation X n+ in which n is the valence of the cation.
3. The composition as claimed in claim 2 , wherein the compounds B conform to the formula (3) below:
where:
each of R 1 , R 3 and R 5 , which are identical or different, is independently a hydrogen or a linear or branched alkyl chain having from 1 to 20 carbon atoms;
each of R 2 and R 4 , which are identical or different, is independently a linear alkyl chain or having from 4 to 24 carbon atoms, it being possible for said alkyl chain to comprise cycloaliphatic groups; and
R 6 is a hydrogen or else a linear or branched alkyl chain having from 1 to 20 carbon atoms.
4. The composition as claimed in claim 3 , which is prepared by only partial sulfonation of a compound of formula (3) or else a mixture of compounds of formula (3) using a sulfonating agent.
5. The composition as claimed in claim 4 , wherein the sulfonation is performed using gaseous sulfur trioxide SO 3 as sulfonating agent.
6. The composition as claimed in claim 5 , wherein the sulfonation is further performed using the falling-film technique.
7. The composition as claimed in claim 1 , further comprising:
an aqueous medium comprising dissolved salts; and/or
an anionic surfactant.
8. The composition as claimed in claim 7 , wherein the anionic surfactant is an AGES or an AAGES.
9. A method for enhanced oil recovery from an underground formation, the method comprising:
injecting a composition as claimed in claim 1 into said underground formation via at least one injection well; and
recovering a fluid conveying the oil leaving the underground formation via at least one production well.