摘要 |
A C-branched zwitterionic surfactant represented by the following formula is disclosed: <IMAGE> wherein x and y are numbers, x is less than or equal to y+1, and the sum of x+y is in the range of about 7 to about 19, with the provisos that: (1) when the sum of x+y is in the range of about 7 to about 13, x/y is in the range of about 0.3 to about 1.2; and (2) when the sum of x+y is in the range of about 14 to about 19, x/y is in the range of about 0.1 to about 0.7. An enhanced oil recovery method using the foregoing surfactants is also disclosed.
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