Thermobaric studies of multifunctional composition based on surfactants

The multifunctional chemical composition based on surfactants and possessing both oil-driving and flow-diverting properties has been developed at the IPC SB RAS. The investigation of the physicochemical properties of the composition performed at 100°С at three pressure values 7.5, 9.5, and 12 MPa and three carbon dioxide concentrations 20, 40, and 60 mol % has revealed that the pattern of changes in physicochemical properties of the composition are almost the same as when the composition was thermostated without CO2. The low temperature composition has a low interfacial tension at the boundary with oil. The urea is partially hydrolyzed during the thermostating. The pH rises and initiates a hydrolysis of aluminum ions. Upon completion of the hydrolytic polycondensation reaction aluminum hydroxide sols are formed. The degree of urea hydrolysis decreases with increasing concentration of CO2 in the reactor. This occurs regardless of the time of thermostating, as with an increase in the concentration of the product of urea hydrolysis reaction—CO2, the equilibrium shifts towards the reverse reaction, that is, towards the formation of urea. Based on the studies performed, it can be concluded that the injection of a multifunctional chemical composition together with carbon dioxide into the reservoir can significantly enhance the oil recovery.