Oil Displacement Evaluation Of P20 Super Molecular Surfactant Under Electric Field

At present,most of the world's oil fields are in the environment of high water cut and unstable international oil price,and low-permeability oil fields have gradually become the main mining body.In the process of oil field exploitation,the effect of electric field on electrochemistry,electroosmosis and electroheating of oil layer is used to improve the percolation capacity and fluid flow performance of oil layer.In this paper,the laboratory physical simulation experiment is carried out for low-permeability oil field to improve oil recovery by means of DC electric field and P20 super-molecular surfactant.Under the action of external electric field,through the experiment of the change of mineral particle size and the influence on the wettability of rock,it is concluded that the electric coalescence phenomenon of clay minerals and fine components occurs under the action of electric field,which makes the pore throat space more unobstructed,so as to improve the permeability of the reservoir.Under the action of electric field,clay mineral particles obviously coalesce and become coarser,which is related to the action time of electric field and the magnitude of electric current.When it's small,the median particle size reaches the peak value in 4 hours,and when it's large,it reaches the peak value in 16 hours.Due to the effect of external electric field,the wettability of reservoir changes to hydrophilic direction.The surfactant used in this paper is a new P20 supra-molecular surfactant,which is composed of polyelectrolyte and surfactant system,this kind of surfactant has strong anti-adsorption ability,which can not only reduce the loss of surfactant,but also improve the utilization rate of surfactant and the effect of oil displacement agent.Under the action of electric field,the critical micelle concentration(CMC)of P20 super-molecular surfactant can be significantly reduced,which is 0.05 lower than that without electric field;the interfacial tension is reduced by an order of magnitude;after 170 hours standing,the water content of the emulsion is more than 98%,and the emulsion stability is better.According to the experiment,the final recovery rate of water drive is increased by 3.28%;under the action of electric field,the cumulative recovery of P20 super-molecular surfactant increased by 5.27%;In electric field flooding,the best potential gradient is 5V / cm;the injection concentration of P20 was 0.15% and the injection amount was 0.3pv.The combination of electric field and P20 super-molecular surfactant can significantly improve oil recovery.