Study On Optimization Method Of Multi-stage Polymer Flooding

Some measures such as polymer flooding must be taken to improve the recovery rate of heavy oil reservoir in high water-cut stage.As a matter of experience,polymer flooding of general injection mode involve many defects,such as high costs,forming high transmssibility pathways.Through theoretical analysis of sweep efficiency mechanism when injectiong different viscosity of polymer solution,using heterogeneous cores displacement experiment further studys the polymer flooding injection order,permeability ratio,oil-water viscosity ratio on the influence of sweep coefficient.Finally,the effect of different viscosity of polymer slug on oil recovery is simulated by numerical simulation.Results show that(1)permeability ratio is an important factor affecting polymer flooding recovery.When the ratio is 2,displacement effect is well.But with the ratio increasing oil displacement effect gets worse;(2)three-concentration-slug polymer flooding is better than single slug,and better than two-slug flooding;(3)when the oil viscosity is less than 65 mPa·s and permeability ratio is 2,three stage Saiju flooding effect is better than the two level of polymer flooding;when the oil viscosity is higher than 65 mPa·s,three-concentration-slug polymer flooding is slightly lower than the two-plug flooding,and the lower viscosity of oil the better flooding effects it can get;(4)three-dimensional homogeneous conceptal model(ratio is 2,the viscosity of oil is 65 mPa·s)polymer flooding numerical simulation results show that the three-slug of polymer flooding is better than single stage and two-slug,which is the same with the experimental rules.