| Polymer flooding can increase the viscosity of the displacement liquid,increase the oil-water ratio,expand the area of the reservoir and increase the recovery rate,so it is widely used in the major oil fields.JiDong Oilfield in the long-term injection of polymer,resulting in high injection pressure,low injection rate of the oil field production has brought a great impact,the urgent need for a reservoir protection technology.In this paper,the mechanism of polymer damage to the reservoir is analyzed,and the damage to the reservoir is minimized by optimizing the parameters of the polymer.In the process of optimizing the molecular parameters of the polymer,the adsorption experiment,the oil recovery experiment and the reservoir damage evaluation experiment were used.The macromolecular polymer was selected,the preferred polymer injection rate was 0.8mL/min-1mL/min,the preferred polymer concentration is 2000 mg / L,and the polymer is preferably used in an amount of 0.6 PV.From the analysis of polymer blockage components to find out the reasons for the formation of plugs.Through the analysis of the composition of the plug,we can see that the main components of the plug are flocculated polymer,stratified crude oil,a small amount of scale and silicate,from the compatibility of the formation of water and polymer anti-high-priced cationic performance to find out The main reason for the formation of the polymer is the reaction of the polymer with the high valency.In order to enhance the degrading ability of the depolymerizing agent,the weak oxidant was replaced by the strong oxidizing agent,and the optimum concentration of the degreasing agent K12 was 0.5%.Chlorine,through the polymer degradation test,the concentration of strong oxidants is preferred 5%.The experimental results show that the recovery rate of the depolymerization agent of the new formula can reach more than 75%,and it has a good depolymerization effect. |
