Simulation Study On High-Concentration Polymer Flooding Of Small Well Spacing In East Block Of Labei

The pilot test is located near the transition zone in the northeast of Lamadian oilfield.The sedimentary facies is mainly channel sand,can be divided into four sedimentary units on the longitudinal.The block is put into development in the year of 1974,which has deployed five sets of development pattern,and divided into 5 sets of development series.The block has come through the conventional water flooding,polymer flooding and high concentration polymer flooding stages.The paper mainly aims at high concentration polymer flooding stage for numerical simulation and optimization design.According to the reservoir data of I1-2 layers in the east block of Labei,the attribute model of objective layer is established based on facies-controlled conditions.The error of model is within 3% through examination.On the basis of fine geologic modeling,the development effects and remaining oil distribution of I1-2 layers in the east block of Labei are predicted,using Eclipse.Through the numerical simulation,the influence factors like well spacing,injection-production ratio,concentration of polymer injection,injection rate,polymer injection amount are studied.The optimal high-concentration polymer flooding schema is the well spacing of 106 m,the injection-production ratio of 1.0,the injection rate of 0.2PV/a,the polymer injection amount of 1750 PV.mg/L,and the slug combination of 3500mg/L(1050PV.mg/L)+2500mg/L(350PV.mg/L)+1500mg/L(350PV.mg/L).The recovery degree of the optimal schema is 10.44%,and final recovery efficiency is 63.65% while the water cut reaches 98%.At last,the timing and methods for high-concentration polymer flooding turned to subsequent water flooding are studied,from the two aspects of the same time and differernt time.Finally determined that gradient descending concentration at 2000mg/L(75PV.mg/L)+1500mg/L(75PV.mg/L)is the optimal solution,in the condition of turning subsequent water flooding in the same time.Meanwhile,in the condition of turning subsequent water flooding in different time,the optimal solution should be the water cut of well group reaches 98% and polymer amount of well group reaches 1750 PV.mg/L.