Study On Foam And Oil Displacement Performance Of Viscoelastic Surfactant System

Foam flooding is an important tertiary oil recovery method,which can effectively improve oil recovery in high water cut reservoirs.At present,the main problem of foam flooding is that the foam is unstable in the formation.To solve this problem,this paper established a viscoelastic system T16/S12 composed of amphiphilic surfactant T16 and anionic surfactant S12,and studied the foam performance,rheological property and oil displacement performance of the system through experiments,and analyzed the internal relationship between the three properties.The results show that the combination of T16 and S12 surfactants can produce synergistic effect and improve the foaming and stability of the aqueous solution,and the resulting foam has a high temperature and salt resistance.A viscoelastic surfactant system can be established by mixing T16 and S12 with a mass ratio of 1:1.The presence of worm-like micelles in the system is the reason for the special rheological properties of the T16/S12 viscoelastic surfactant system.The results of bulk rheological test show that the T16/S12 viscoelastic surfactant system has good shear dilution performance.The experimental results of interfacial rheology show that the interfacial expansion rheology of T16/S12 foam is affected by shear force and concentration change.The larger the shear rate,the smaller the surfactant concentration,the larger the interfacial expansion modulus and the more unstable the foam.Oil displacement performance shows that T16/S12 viscoelastic surfactant system can significantly improve oil recovery.The main reason to improve oil recovery is to improve the formation homogeneity by effectively plugging the high-permeability layer with foam,so as to greatly increase the conformance coefficient of water flooding.In addition,the viscoelastic properties of the system and emulsifying properties of crude oil are used to improve oil recovery.T16/S12 viscoelastic surfactant system has a certain internal relation between oil displacement performance,foam performance and rheological property.The existence of worm-like micelle and small foam interface expansion modulus in the system are conducive to the generation of stable foam.The more stable the foam is,the better the flooding effect will be.