following flooding water thereby achieving the desired interfacial tension reduction between the injected fluid and the displaced fluid without loss of surfactant on the formation matrix the surfactant may be present in a hydrocarbon solvent or in an aqueous solution or in a combination thereof any type of surfactant known in the art may be used in the practice of this invention some types of surfactants were mentioned previously in addition surfactants disclosed and claimed in the following u s patents are particularly useful since they have been found to be capable of performing in reservoirs having both high salinities and high hardness levels u s pat nos 3 858 656 3 811 505 3 811 504 3 811 507 likewise the amount of surfactant which must be employed in the practice of any chemical flood is generally known in the art and is to be found in published literature however the concentration of surfactant generally will range from 0 01 to 0 1 pore volumes of an aqueous surfactant solution having dissolved therein from 0 001 to 0 5 percent by weight of the surfactant itself as mentioned before in addition to a preflush or a substitution thereof a small amount of the sacrificial material may also be added to the surfactant solution to prevent the adsorption of the surfactant on the formation matrix in carrying out this invention a sacrificial material comprising alkoxylated asphalts is injected via the suitable injection means i e through one or more injection wells completed in the subterranean hydrocarbon formation.