Effectiveness Evaluation Of SP Flooding After Polymer Flooding In JZ9-3 Oilfield

JZ9-3 oilfield water flooding to 75% water cut,into polymer flooding,injected 0.3 PV,without subsequent water flooding,directly into binary composite flooding,which is different from the onshore oilfield chemical flooding development model.The polymer injected in the polymer flooding stage still plays an important role in the injection process of binary composite system.The development characteristics show that there is no secondary funnel in the water cut of binary composite flooding stage.Therefore,it is necessary to quantify the contribution of polymer and binary composite system to oil production,so as to accurately evaluate the development effect of binary composite flooding.In this paper,numerical simulation,physical simulation and dynamic analysis are combined to evaluate the development effect of binary composite flooding in JZ9-3 oilfield.This paper establishes dynamic index change method,water cut descending funnel method and water cut ascending velocity change rate method for judging effective time of single well,and the method of adding oil per ton to judge the effective time of the whole area,the effective time of binary composite flooding for each single well and whole area in the target oilfield is given.According to the determined effective time,the oil increment of binary composite flooding is evaluated by net oil increment method,water cut rise method,numerical simulation method and displacement characteristic curve method.Comparing the actual production with the calculated production before the binary flooding effect,it is found that the displacement characteristic curve method has the highest accuracy.By January 2017,the oil increment is 12.05×104m3,and the recovery degree is increased by 0.81%.Two different tracers were used to represent polymer injected in polymer flooding and binary composite flooding respectively.The relationship between the concentration and net outflow of two polymers and surfactants in the grid and oil displacement was studied by tracer flow simulation method.The results show that when the oil saturation is low,the role of polymer in binary system will decrease.The correlation between net outflow and displacement of two polymers is the highest,and the relationship between them is obtained by fitting.The formula is used to calculate the contribution of injected polymer to displacement effect in binary flooding stage of target oilfield is 1.59 times that of injected polymer in polymer flooding stage.In order to improve economic efficiency,the chemical flooding method at the end of binary compound flooding in JZ9-3 oilfield was optimized under equal economic conditions.Laboratory physical experiments and numerical simulation show that the scheme of "0.024 PV polymer concentration 2500 mg/L,0.05 PV binary system 1200 mg/L P+0.2% S,alternate injection of 2 cycles" is recommended to adjust the development of target oilfields.Laboratory physical experiments and numerical simulation can increase oil recovery by 0.7% and 0.52% respectively compared with the current scheme.