Impact of shale on properties and oil recovery potential of sandstone formation for low‐salinity waterflooding applications

Abstract

AbstractPorous and permeable formation, namely, sandstone, may also contain water‐reactive clays that swell in the presence of water and cause damage to formation by reducing its permeability. The inclusion of salts in injected water (called low‐salinity water) is considered successful to inhibit shale swelling. Therefore, this study reports the impact of shale content (0–25%) on porous and permeable sand‐packs in the presence of fresh water and salt solutions (KCl/CaCl2, 0–4 wt%). The properties of sand‐packs were found to be significantly affected by shale; porosity reduced by ~34% with 25% of shale, whereas permeability could not be measured due to no flow. KCl addition was relatively favorable as 2 wt% KCl offered least impact of shale on sand‐pack properties. Interestingly, sand‐pack that exhibited no permeability in water recovered significant permeability in the presence of KCl of 2 wt%. As a result, the oil recoveries of sand‐packs were higher than the ones with water, and moreover, sand‐pack with 25% shale content showed 27% original oil in place, which was negligible in presence of water. Thus, the study concludes that a salt solution of 2 wt% KCl can be very effective in shaly sandstone that faces challenges in conventional water flooding applications.