Experimental Study On Performance Evaluation Of Deep Flooding System Of Emulsion Polymer Weak Gel

As a deep adjustment technology,weak gel profile control has various advantages,such as fast dissolution rate,low cost,simple dispensing process,strong fluidity and good shear resistance.In this paper,a new emulsion polymer cross-linking system is screened according to the conditions of the marine profit-making oilfield group.The indoor static performance experiment evaluated the effect of polymer molecular weight,degree of hydrolysis and concentration on the stability of the polymer solution.And the type and concentration of this emulsion polymer was preferred.The effects of the type and concentration of different crosslinkers on the gelation time and gel strength of the system were evaluated.Crosslinker type and concentration was preferred.The microstructure of the gel was analyzed by scanning electron microscopy to clarify its structural characteristics.The plugging performance,long-distance transport characteristics,oil displacement performance and permeability adaptability of the emulsion polymer flooding system were evaluated by the physical sand filling model and the sand filling model(10 m).The results show that the system has best properties when the molecular weight of polymer is 1500×104,the concentration is 2000 mg/L and the degree of hydrolysis is 20%.The crosslinking agent used in this system are 0.06 wt% phenolic crosslinker I and 0.09 wt% phenolic crosslinker II.The gelation time of the system is 20 d and the viscosity is 1011 m Pa·s.The viscosity retention rate in 10 d is 81.44%.The microstructure of the weak gel system is a hexagonal three-dimensional network structure,which has good stability.The results of physical sand filling model test show that when the injection rate is 5 m/d and the slug size is 0.5 PV the blocking rate of the emulsion polymer shifting system in the sand filling model(1 m)is over 90%;the size of the injected slug is at 10 PV.The average blocking rate of the system in the 10 m sand filling model is 98%,and the pressure gradient is as high as 2.1 MPa/m.The enhanced core recovery rate of homogeneous core permeability is 5000×10-3 ?m2,which is 20.78%.When the heterogeneous core grade is 6(500/3000×10-3 ?m2),the oil recovery is enhanced,which increases 22.59%.The emulsion type polymer weak gel control system preferred herein has a comprehensive function of transporting to the deep part of the reservoir to perform deep profile control and oil displacement.It can provide data and theoretical basis for the deep control system of the offshore profit field.