Study On The Effect Of Oil/Polymer Viscosity Ratio On Polymer Flooding

In the process of implementing polymer flooding to improve oil recovery,controlling the reasonable mobility ratio is an important factor to ensure the oilfield increase.When studying the effect of mobility ratio on oil displacement efficiency,the complexity of the fluidity ratio makes the research difficult and the workload increases.Therefore,from the viewpoint of viscosity,as a preliminary evaluation method,it can enhance the pertinence of research when focusing on the viscosity ratio of formation crude oil and polymer solution to simplify the study of mobility ratio,which is of great significance to improve the efficiency of oilfield development.In this paper,the oil/polymer viscosity ratio of crude oil viscosity in thin oil reservoir and common heavy oil reservoir is studied.The conclusions and main achievements are as follows.The simulated oil viscosities of medium and low viscosity(10.8mPa·s,49.0mPa·s,71.1mPa·s)and high viscosity(177.1mPa·s,320.5mPa·s)were selected to replace crude oil viscosities,and five viscosity ratios were matched for each viscosity,including the range of 0.1-7.The experimental results of effect of viscosity ratio on recovery factor under polymer flooding conditions shows that when the injection amount of polymer solution reaches 5 times of the pore volume,the oil displacement effect reaches the upper limit and the recovery rate reaches peak value.Under each simulated oil viscosity condition,the polymer recovery increases gradually with the decrease of the viscosity ratio,and the amount of increase decreases.The polymer recovery of low viscous oil eventually reaches equilibrium,and the optimum viscosity ratio is obtained.The optimum viscosity ratio of ?o=10.8 mPa s is 0.1245,the optimum viscosity ratio of ?o?49.0 mPa s is 0.1695,and the optimum viscosity ratio of ?o=71.1 mPa s is 0.1755.And as the viscosity of the simulated oil decreases,the optimum viscosity ratio also decreases.The injection test of the polymer solution AP-P4 shows that the high viscosity polymer has large resistance coefficient and residual resistance coefficient,so the injection pressure is large and the injection performance is poor.The final high-viscosity polymer flooding recovery is a continuously rising curve and the best viscosity ratio was not found The experiments on the effect of viscosity ratio of water flooding and polymer flooding on oil recovery show that the crude oil has a certain scope of application for polymer flooding effect.When the viscosity ratio(crude oil viscosity)reaches 0.313(190mPa s),the effect of polymer flooding to improve oil recovery is the most obvious,which is 6.51%.When the viscosity ratio(crude oil viscosity)is higher than 0.313(190mPa·s),the overall oil recovery is increasing,but the effect of improving oil recovery is weakened.