Nanoparticles (D~1 to100 nm) as part of nanotechnology have drawn the attention for its great potential of increasing oil recovery. From the authors’ previous studies, wettability alteration was proposed as one of the main Enhanced Oil Recovery (EOR) mechanisms of nanoparticles fluid. Adsorption of nanoparticles on pore wall lead to wettability alteration of reservoir. We conducted a series of wettability measurement experiments with water, neutral and oil wet core plugs, where we systematically varied nanoparticles concentration and size of nanoparticles. Nanoparticles transport experiments were also performed for three different wettability core plugs with varying flow rate, injection pattern as well as concentration and size of nanoparticles. Effluent nanoparticles concentration was measured to evaluate nanoparticles adsorption and retention in the core and also desorption during water post-flushes afterwards. Both silica hydrophilic nano-structure particles and colloidal nanoparticles were utilized in above two experiments.
The results of wettability alteration experiments indicated that hydrophilic nanoparticles have ability of making the cores to more water wet, especially for neutral and oil wet cores. Concentration and size of nanoparticles have significant effect during wettability alteration process. For nanoparticles transport experiments, the results showed that the nanoparticles undergo both adsorption and desorption as well as retention during injection. Effluent nanoparticles concentration curves were plotted to find the breakthrough time. Experiments with varying concentration, particle size and flow rate yield magnitude of nanoparticles adsorption and desorption ability for Berea sandstone. Porosity and permeability impairment were observed during nanoparticles dispersion injection.