The Effect of Divalent Ion Addition to Rhamnolipids Solution Through Fluid-to-Fluid Testing for Enhanced Oil Recovery: A Review

Enhanced oil recovery (EOR) continues to be developed to optimize oil production from mature oil fields.One promising EOR method is the use of biosurfactant solutions, which are environmentally friendly and can reduce oil-water interfacial tension, enhancing the mobility of trapped oil in reservoir rocks.However, the effectiveness of rhamnolipid biosurfactants is strongly influenced by geochemical conditions, particularly the presence of divalent ions such as calcium (Ca) and magnesium (Mg) in formation water.This study aims to investigate fluid-to-fluid interactions between rhamnolipid solutions and divalent ions to improve oil recovery efficiency.Experiments were conducted to investigate the effects of adding calcium and magnesium ions on the physicochemical properties of rhamnolipid solutions, including changes in interfacial tension and rheological properties.Imbibition and precipitation tests were also conducted at the laboratory scale to evaluate the effectiveness of rhamnolipid biosurfactants in enhancing oil recovery.The results showed that, in terms of both interfacial tension reduction efficiency and viscosity of the emulsion formed, the presence of divalent ions can have a significant impact on biosurfactant performance.Under certain conditions, divalent ions can reduce the efficiency of oil mobilization.However, by optimizing the rhamnolipid biosurfactant formulation with the appropriate concentration of divalent ions, recovery efficiency can be improved.This study provides valuable insights into the development of biosurfactant-based EOR technologies, particularly for reservoir environments with high divalent ion content.The results are expected to serve as a foundation for developing more stable and efficient biosurfactant solutions for applications in the oil and gas industry.