Ether phosphonate surfactants having branched hydrophobic tails and their use in an enhanced oil recovery process

摘要

Novel ether phosphonate surfactants having a branched hydrophobic tail are used in a process for enhanced oil recovery from a subterranean oil reservoir. They combine a high oil-mobilizing capacity with a good tolerance against divalent ions. The ether phosphonate surfactants are summarized by the formula where R1 and R2, being the same or different, are hydrocarbons containing 3-18 carbon atoms each and optionally containing functional groups such as ether and hydroxyl; X is an alkyleneoxy group derived from an alkylene oxide having 2-3 carbon atoms; Y is an alkylene group having 1-4 carbon atoms; R3 is an alkyl group having 1-4 carbon atoms; M+ is a monovalent cation; n1 and n2, being the same or different, are a number from 0 to 4; m1 and m2, being the same or different, are 0 or 1, both m1 and m2 not being 0 at the same time and m1 being 1 when n1 is a number from 1 to 4 and m2 always being 1 when n2 is a number from 1 to 4; and p is a number from 0 to 10.