| http://www.w3.org/ns/prov#value | - Petroleum may be recovered from petroleum containing formations having high salinity and/or high temperature by injecting into the formation an aqueous fluid containing an effective amount of a surface active agent characterized by the formula: ##STR1## wherein R is an alkyl or dialkyl containing from 4 to 24 carbon atoms; n is an integer of from 2 to 4; m is an integer of from 1 to 50; and M is a
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