Effect of 1-Pentanol on Wettability of Oil/Brine/Rock Systems

In this article, we evaluated the potential of applying a medium-chain alcohol like 1-Pentanol in low-salinity waterflooding. We reported for the first time the contact angle of a variety of Oil/Brine/Rock systems when 1-Pentanol was present or absent in the brine solution. Adding 1 wt% 1-Pentanol to the brine only produced a modest effect on the contact angle of an oil from a sandstone reservoir on sandstone-like substrates (i.e., mica and quartz) in NaCl and MgCl₂ solutions over concentrations of 0-3 M. We also observed that adding 1 wt% 1-Pentanol to the brine could significantly lower the contact angle of an oil from a sandstone reservoir on carbonate-like substrates (i.e., calcite) in NaCl and MgCl₂ solutions over concentrations of 0-1 M. Notably, the contact angle of the Oil/NaCl/Calcite system at 0.1M NaCl was reduced by ~80° after 0.5 wt% 1-Pentanol was added to the brine, indicating that the surface became strongly water-wet which may favor oil recovery. The zeta potential of rock/brine and oil/brine interfaces were also measured and discussed to understand the trends observed in contact angle. These findings may provide new perspectives and insights to low-salinity waterflooding.