Effect of ASP composition on the emulsion-stabilizing properties of simulative produced liquid by ASP flooding

Key words:  alkali/surfactant/polymer flooding  stability  dynamic characteristics  interface viscoelasticity  Zeta potential

Abstract:

The influences of the ASP composition on the stability of weak base petroleum sulfonate simulation produced liquid by ASP flooding were studied, which were stable kinetic parameters, interface viscoelasticity and diffusion Zeta potential. And the influence mechanism of ASP composition on these parameters was investigated as well. The results show that the surfactant adsorbs at the oil-water interface due to its amphiphilic properties, and the stability of oil-water interfacial membrane increases with the increasing of surfactant mass fraction. When the concentration of surfactant is more than 0.1％, the stability of the crude oil emulsion is increased, and then the demulsification becomes difficult. Sodium carbonate plays a dual role in the ternary compound system. When the mass fraction of alkali is less than 0.8％, sodium carbonate reacts with the acidic substances in crude oil, and the surface active substances generates. The strength of oil-water interface membrane and the stability of the simulative produced liquid emulsion are increased because of the absorption of the surface active substances on the oil-water interface. When the mass fraction of alkali is more than 0.8％, the main function of sodium carbonate is neutralizing the charge of the surfactant molecules in the membrane of oil-water interface. The diffused double layer of oil-water interface is compressed, and the stability of crude oil emulsion is decreased. The main role of polymer is increasing the viscoelasticity of oil-water interface. The effective numbers of molecules adsorbed on the oil-water interface increases with the increasing of polymer concentration. The viscoelasticity of oil-water interface is increased, and the stability of simulation produced liquid is enhanced.