Imbibition behavior of surfactant in water-wet sandstone and its effects on recovery efficiency

Key words:  spontaneous imbibition  outcrop sandstone  water-wet cores  surfactant  imbibition recovery efficiency

Abstract:

Spontaneous imbibition behavior of brine, nonionic surfactant solution, anionic surfactant solution, and cationic surfactant solution and its effects on recovery efficiency were studied in water-wet Chinese outcrop sandstones. The imbibition charateristics were compared in brine, surfactant solution, and sequence of brine and surfactant solution. The results show that the ultimate imbibition recovery efficiency of brine is between 0.32 Woo1P and 0 50 Wqq^，where m；ooip refers to the original oil-cut, and that of nonionic surfactants is between 0.38 and 0.50m;ooip , and that of anionic surfactants is between 0.44 Wqq and 0.55 ，and that of cationic surfactants is between 0.38w00IP and 0.44 The same type of nonionic surfactant with a specific structure could reach the best imbibition results. The imbibition recovery efficiency of anionic surfactant is generally better than that of any other type surfactant. Moreover, if cores are first imbibed in brine and then in surfactant solution, the ultimate recovery efficiency will be improved by (002 -0, 04)m;ooip.