Optimizing nanoparticle retention and oil displacement efficiency in enhanced oil recovery using bio-CaCO₃ nanofluids: a response surface methodology approach

Investigating the factors that influence nanoparticle retention and their relationship to oil displacement is crucial during nanofluid flooding. This work examines the factors influencing the retention of bio-nanoparticles and oil displacement into porous media at reservoir temperatures ranging from 25 to 60 °C, a NaCl salinity of 40,000 -60,000 ppm, and a nanofluid concentration of 0.01–0.05 wt.%. The optimum conditions for the above variables in enhanced oil recovery were determined by applying response surface methodology. Fifteen forced imbibition tests were performed using a core flooding setup. The model predictions aligned well with the experimental forced imbibition data, indicating that significant oil recovery could be achieved under these standard conditions. In addition, the Box-Behnken design suggested a model with an R² value of 0.98, predicting that the maximum oil displacement efficiency is 32.75% under an optimum salinity of 61,414 ppm NaCl, a reservoir temperature of 52.5 °C, and a nanofluid concentration of 0.025 wt.%. Salinity has an insignificant effect on oil recovery but strongly affects the retention of nanoparticles. Temperature and nanofluid concentration significantly affect oil displacement efficiency and retention. In addition, the interaction between the temperature and concentration is recognized as a meaningful effect that reverses the impact on oil recovery.