Effect Of Stability On Oil Displacement Mechanism And Seepage Law Of Polymer Surfactant Flooding

Polymer surfactant is a new type of functional polymer which can improve recovery after polymer flooding.And it is currently in the stage of field test.The samples were extracted mostly in the injection wells and extraction wells when polymer surfactant was analysised in oil field,but the solutions used for laboratory experiments are now available.The results of the analysis are only at the level of performance before injection and the effect after injection.However,it will take hundreds of days to migrate polymer surfactant from the injection well to the production well.During the seepage process,the viscosity stability will be changed by the pore structure.How to affect the oil displacement and seepage law when the viscosity stability of the polymer surfactant is changed is still lack of research.In order to solve the above problem,this paper simulates the polymer surfactant between the injection well and production well with a 30-day Huading I polymer surfactant and Haibo BI polymer surfactant.The performance difference of the polymer surfactant before and after the statics was studied through laboratory experiments.The micro displacement mechanism of the initial polymer surfactant solution and the stationary polymer surfactant solution were compared by the lithographic glass experiment,and the micro displacement mechanism of the two forms was described.The physical experiment simulation of two layers of heterogeneous model and four layers of heterogeneous model was used to compare and analyze the difference of macroscopical seepage law before and after the stating of the polymer surfactant.Based on the above research,this paper draws the following conclusions.In the lithographic glass experiment,after static,the relative swept area of the Huading I polymer surfactant was 4.3% higher than that before the statics,and the relative swept area of the Haibo BI polymer surfactant was 7.7% higher than that before the statics during polymer surfactant flooding;the viscoelastic and emulsifying properties of the stationary polymer surfactant solution are improved.In the two layers of heterogeneous core flooding experiment after polymer flooding,the proportion of oil production in the low permeable layer accounted for 8.17% and 0.19% of the total saturated oil,and the percentage of oil production in high permeability layer was 7.48% and 11.65% respectively in the phase of Huading I and Haibo BI polymer surfactant flooding stage;the proportion of oil production in the low permeable layer accounted for 5.94% and 4.06% of the total saturated oil,and the percentage of oil production in high permeability layer was 6.56% and 6.23% respectively in the phase of stationary Huading I and Haibo BI polymer surfactant flooding stage.The results show that the surfactant solution has better profile control effect and can make the low permeability layer available,but to a certain extent,it will plug the low permeability porosity.It will also limit the high permeability layer’s swept volume due to the high viscosity,resulting in the decline of the oil proportion of the high permeability layer.In the four layers of heterogeneous mode experiment,the oil proportion in the low permeability layer was 4.44% and 8.63% of the total saturated oil,respectively,and the middle permeability layer was 19.29% and 2.28% respectively in polymer surfactant flooding of Huading I and Haibo BI polymer surfactant;the oil proportion in the low permeability layer was 10.05% and 13.15% of the total saturated oil,respectively,and the middle permeability layer was 16.14% and 11.48% respectively in polymer surfactant flooding of stationary Huading I and Haibo BI polymer surfactant.It shows that the polymer solution can effectively plug the large pore channels of extremely high and high permeable layers,so that the remaining oil in the medium and low permeable layers can be greatly used.