Development And Evaluation Of Plug Removal Agent For High Pressure Polymer Flooding Wells

Ploymer flooding as an important tertiary recovery technology to increace efficiency industrialized in Shengli,Daqing Oilfield and so on.It is a common phenomenon that formation blockage in injection well bottom was influenced by polymer molecular entanglement,weak gel degeneration,formation ion and particles.The study found that the cause of the polymer injection well oil pressure high and tough injection is the adsorption of the polymer solution and the plugging of gel,the latter is more serious.At home and abroad,three aspects of plugging removal technology had been studied in the biological,physical,chemical,and obtained the certain effect.The degradation of polymer molecules and viscosity break is mainly research on plugging removal.But the corrosion study of polymer gel is less.In this paper,staring from the viscosity break of polymer solution and the degradation of polymer gel,we get a safe and efficient cleaning system of plugging removal agent.In this paper,two kinds of efficient oxidant was determined by screening the match of strong oxidizing agent and activator,calcium peroxide/citric acid and persulfate.By screening the match of strong oxidizing agent and activator,Calcium peroxide/citric acid and GNS were found.The GNS is composed of strong oxidant GNS-A,activator GNS-B and corrosion inhibitor GNS-C.The orthogonal experiment determined GNS as the best choice and optimized the formula ratio of GNS-A:GNS-B:GNS-C=1%:0.6%:0.5%.In the corrosion rate experiments,the corrosion rate of GNS is 0.0698mm/year at concentration2.1%.The steel was mainly mottled corrosion.Simulation experiment show that with the increasing of the GNS injection concentration,the core permeability and the injection volume multiple,the recovery of core permeability increased.When the injection volume is 2PV and the plugging removal agent is over 2.1%,the recovery of core permeability is more than 92%,it can satisfy the field requirement.This plug removal system is tested in Jidong and Shengtuo oilfied,with the injection of the plugging removal agent,the pressure declined rapidly and the permeability recovered obviously.The daily fluid production increase about 40 m~3 and the permeability recovery is obvious。The plugging removal agent GNS could degrade polymer and gel staying in the pore effectively and improve the production.It is a great significance to the oilfield production.