FUNDAMENTAL AND APPLIED ASPECTS OF PHYSICAL AND CHEMICAL METHODS FOR ENHANCED OIL RECOVERY, CREATED AT THE INSTITUTE OF PETROLEUM CHEMISTRY SB RAS. SURFACTANT-BASED COMPOSITIONS FOR ENHANCING OIL RECOVERY

The proportion of hard-to-recover oil reserves in the world and in Russia is constantly growing. The development of hard-to-recover reserves, including high-viscosity oil deposits, low-permeability reservoirs, and difficult production conditions, such as the Arctic, is becoming an increasingly important factor in maintaining high levels of oil production. For the effective development of hard-to-recover reserves, physicochemical and complex technologies for increasing oil recovery have been developed at the Institute of Petroleum Chemistry SB RAS on the principles of green chemistry, buffer self-regulating systems and the method of deep eutectic solvents (DESs) using the smart compositions of surfactants, coordinating solvents, and complex compounds. The compositions chemically evolve in the reservoir with the acquisition and long-term preservation of colloidal chemical properties that are optimal for oil displacement. Factors causing chemical evolution include thermobaric reservoir conditions, interaction with reservoir rock and reservoir fluids. The review presents the fundamental and applied aspects of the physicochemical and complex methods for increasing oil recovery, developed at the Institute of Petroleum Chemistry SB RAS, the results of laboratory studies, field tests and industrial use of technologies for increasing oil recovery from the oilfields with hard-to-recover reserves under natural development mode and thermal steam influence, including the deposits of high-viscosity oils. Technologies are environmentally friendly and technologically efficient. To implement the technologies, acid and alkaline oil-displacing compositions based on surfactants and buffer systems with adjustable viscosity and high oil-displacing ability have been developed. The results of laboratory studies of phase equilibria, physicochemical, acid-base and rheological properties in surfactant - DES systems containing polybasic acid, polyols, urea, aluminium and ammonium salts are presented. The developed compositions possess the following advantages: they are compatible with formation waters, low-freezing ((-20)-(-60) °С) or solid, have low interfacial tension at the boundary with oil, applicable in a wide temperature range (10-200 °C). The industrial use of these technologies will make it possible to extend the profitable operation of fields with hard-to-recover oil in a wide range of climatic conditions, including the Arctic.