Scheme Optimization And Economic Limit Study On Polymer Injection Extension In Shengtuo Oilfield

As an important and effective EOR technology,polymer flooding has been extensively applied in onshore oilfields and achieved great success.Since oil price dropped sharply from the second half of 2014,it requests more stringent on polymer flooding.It is imperative to improve the quality and efficiency of polymer flooding projects.The polymer flooding at E_d34 unit in Sheng2 area of Shengtuo oilfield is at the peak period of the effectiveness,with average oil production of 6.9 t/d and water cut of 89.0%.The injection volume has completed 83.7%of the plan,and it would be turned to water flooding after the planned volume is completed.According to the effective pattern of chemical flooding,the follow-up water flooding would present rapid increase of water cut and the performance would get worse.Polymer injection extension can be used to slow the speed of water-cut returning,and to extend the peak period of the effectiveness.However,it would inevitably increase the consumption of polymer,which would affect the economic benefit.Therefore,it is necessary to optimize the injection parameters to maximize the effect of polymer flooding,so as to obtain the best economic benefit.In this thesis,the scheme optimization and economic limit of polymer injection extension in Shengtuo oilfield has been studied by both laboratory experiments and numerical simulation.The effective characteristics of polymer flooding were analyzed and the injection parameters were optimized.The injection-production adjustment and layered injection was also included in the scheme.After field implementation,the water cut was kept below 92%,and oil production rate remained 4.1t/d per well.The enhanced oil recovery was estimated to reach 8.3%,which proves the correctness of polymer injection extension to enhance oil recovery.The whole-process economic evaluation was carried out by comparison of with and without project.The economic limits of polymer injection project and extension project were established under different oil prices and polymer prices.And the maximum consumption of polymer project was optimized accordingly.Under Shengli oil price of$50/bbl and polymer price of 12,000 yuan/ton,the maximum consumption of polymer in E_d34 unit was 1650PV·mg/L.The results can be used to guide the economic evaluation and maximum consumption optimization of 11 injecting chemical flooding projects with OOIP of 85.7million tons.