Permeability thickening fluids for improved secondary oil recovery

Waterflooding is limited by zones of spatially varying permeability which cause channelling. More crude oil could be produced by a more uniform water/brine front across layers of different permeabilities. Novel non-polymeric water additives (CTAB+NaSal in brine) are used to selectively slow down flow of water in high permeability zones. In order to isolate rheological effects from rock fluid interactions, we have carried out experiments on inert glass cores. A monotonic increase of viscosity as function of permeability is observed for the range 45–2200 mD (covering typical reservoir ranges). This effect can be referred to as permeability thickening. This result opens up the possibility of tunable fluid engineering for any given permeability distribution of reservoirs. Low additive concentrations