LJS/HPAM high-efficiency viscoelastic oil displacement system

In order to research the effective EOR method for high-temperature and high-salinity oil reservoirs and explore the application feasibility of high-efficiency viscoelastic system to high-temperature and high-salinity oil reservoirs, the viscoelastic wormlike micelle system was prepared by adding the low-concentration polymer (HPAM) into the carboxylic-type erucamidopropyl hydroxysultaine (LJS) solution in the simulated condition of high-temperature and high-salinity oil reservoir (salinity 20 000 mg/L, bulk concentration of calcium and magnesium ions 500 mg/L, and reservoir temperature 80 ℃). In addition, the effects of salinity, temperature and aging time on the viscoelastic wormlike micelle system were studied. It is indicated that in the harsh conditions of simulated high-temperature and high-salinity oil reservoir, the viscosity of the viscoelastic LJS/HPAM composite system is up to 37.22 mPa · s and the oil-water interfacial tension drops to the order of 10⁻² mN/m. When the temperature is constant and the salinity is increased, the viscosity and interfacial activity of LJS/HPAM composite system are basically unchanged, and even after aging of 90 d, the system still presents good stability. The laboratory simulation experiment of oil displacement confirms that LJS/HPAM composite system can increase the oil recovery factor greatly (increase amplitude 16.22%). The research results play a guiding role in the actual application of surfactant-polymer composite systems in high-temperature and high-salinity oil reservoirs.