In the third cycle, no additional oil recovery was obtained in the core B31 due to the effect of the high saline SW at the end of the second cycle. A little oil recovery of 0.75% was observed in the core B35 for the same reason as mentioned above. The improved oil recovery in the cores B45 and B47 was 1.2 and 1.85% of the OOIP, respectively. It is obvious that lower injected water salinity triggers the sandstone wettability to become more water-wet, allowing for more oil to be detached from Berea sandstone core plugs.