| 摘要 |
The present invention relates to a method for the assisted recovery of crude oil from an underground formation, comprising: a) injecting, via at least one injection means in contact with the underground formation containing the crude oil, a liquid containing a mixture of at least: i) a salty aqueous medium, ii) a mixture of two zwitterionic viscosising surfactants or a mixture of two populations of said surfactants having a bimodal characteristic of the narrow distribution of Ri groups as defined below, in a weight content of between 1 and 0.05 wt %, preferably between 0.5 and 0.1 wt %, and more preferably between 0.4 and 0.15 wt %, such that the liquid has an oil/water interface tension of about 10 mN/m (milinewton per meter) or less as measured at room temperature (25° C.) and a viscosity of about 3 cPs or more as measured at a temperature of 80° C. for a shearing gradient of 10 s−1, and corresponding to formula (1) where the two Ri radicals of the two surfactants or surfactant populations have a difference in the number of carbon atoms thereof that is at least greater than or equal to 4. The method comprises using at least one production means located at a different location than that at which the liquid or the polymer has been fed in order to recover the liquid containing the crude oil.; |
| 主权项 |
1. A method for assisting recovery of petroleum from a subterranean formation comprising:
a) injecting into the subterranean formation, a drive fluid comprising a mixture of:
an aqueous medium comprising a salt; and0.05 to 5% by weight of a mixture of two viscosity-improving zwitterionic surfactants, or a mixture of two populations of zwitterionic surfactants each comprising a narrow distribution of R1 groups; wherein the zwitterionic surfactants comprise a compound of formula:wherein:
A− comprises a carboxylate COO− or sulfonate SO3− group; R1 comprises a hydrophobic moiety of an alkyl, alkoxyalkyl, alkylaminoalkyl, or alkylamidoalkyl group,
further wherein:
R1 is linear or branched and comprises about 16 to 30 carbon atoms, andthe difference between the number of carbon atoms in radicals R1 of the two zwitterionic surfactants, or of the centers of the distributions of R1 groups of each of the two populations of zwitterionic surfactants, is equal to or greater than 4; R2 and R3 independently comprise an aliphatic chain having from 1 to 30 carbon atoms, wherein said aliphatic chain is linear or branched, saturated or unsaturated; and R4 comprises an alkylene group having from 1 to 4 carbon atoms, optionally substituted with a hydroxyl group; further wherein the drive fluid exhibits:
an oil/water interfacial tension of about 10 mN/m or less at 25° C., anda viscosity of at least about 10 cP at 25° C. and with a shear gradient of 10 s−1, and b) recovering the drive fluid and the petroleum from a different location than where the drive fluid was injected. |
