Abstract: Washburn method is applied to investigate the different effect of molecular deposition filming flooding agent (MDFFA), tetraethyl ammonium bromide [(Et)4NB] and hexadecyl trimethyl ammonium bromide (CTAB) on the wettability of oil reservoir minerals. The results show that the oil reservoir minerals absorbed MDFFA or (Et)4NB are more hydrophilic than that of those minerals absorbed CTAB. The hydrophilicity of Daqing and Zhongyuan oil sands rises after absorbing MDFFA or (Et)4NB. The oil wettability of most oil reservoir minerals declines after they absorbed different quaternary ammonium salts. The oil wettability of asphaltene oil reservoir minerals rises after they absorb different quaternary ammonium salts (except for asphaltene kaolin). The oil wettability of Daqing and Zhongyuan oil sands treated by MDFFA before and after adsorb asphaltene are lower than that of those minerals treated by (Et)4NB or CTAB, which are of important significance to water flooding and tertiary recovery. 

Key words: molecular deposition filming flooding agent, quaternary ammonium salt, wettability, oil reservoir minerals, Washburn method