Mechanism study and formula development by numerical simulation and visualization experiment in a microfluidic system for enhanced oil recovery

•A microfluidic model containing the novel microstructure was designed and fabricated.•The mechanism of chemical flooding was studied through the combination of computational fluid dynamics simulation and visualization experiments.•The model equation for enhanced oil recovery was derived by dimensional analysis, which was related to capillary number, oil–water density ratio, and porosity.•Cardanol-based surfactants and operating conditions were proposed based on the resulting empirical formula. In this study, microfluidic system was adopted to investigate the effects of hydrodynamic factors on chemical flooding. The combination of visualization experiments and computational fluid dynamics (CFD) simulations was used to evaluate the effects of flow rate, interfacial tension (IFT), viscosity, density, contact angle and porosity on EOR (enhanced oil recovery). The chemical flooding regulation model was built through dimensional analysis of hydrodynamic factors, affording oil displacement empirical formula for oil displacement by fitting EOR data. The empirical formula displayed high applicability within a certain range of capillary number (Ca), oil–water density ratio and porosity. In addition, the empirical formula was expected to guide the development of a cardanol-based surfactant, whose preparation process was optimized in the microreactor. These findings would provide useful references for understanding the EOR mechanism of chemical flooding at micro-scale.