Study On The Polymer Table Binary Compound Flooding System In Zone B Of M Oilfield

Chemical flooding is one of the important ways to improve oil recovery.Polymer flooding can usually improve oil recovery by about 10%in high permeability reservoirs,and has great development potential.ASP flooding can improve oil recovery by about 20%in high permeability reservoirs,but alkali causes a series of problems,such as scaling,demulsification difficulties,and increasing polymer dosage.With the development of polymer viscoelastic flooding mechanism and new surfactants,binary surfactant flooding has become the focus of chemical flooding to improve oil recovery.After long-term waterflooding development,medium and low permeability oilfields have entered the stage of medium and high water cut.It is of unique significance to study the application of poly-surfactant binary flooding system in medium and low permeability reservoirs.Therefore,according to the characteristics of Yan101-2 reservoir in B area of M oilfield,through the combination of surfactant and polymer,a binary polymer flooding system with high stability,which can not only effectively improve solution viscosity but also achieve ultra-low interfacial tension under certain salinity conditions is screened out.This paper investigates the reservoir characteristics,development characteristics and enhanced oil recovery by chemical flooding of medium and low permeability reservoirs at home and abroad,and summarizes the present situation of laboratory research and application of binary compound flooding in medium and low permeability reservoirs.In view of the problems faced by Yan101-2 reservoir in Area B of M oilfield,such as large amount of remaining oil not being recovered,difficulty in stabilizing production,slow recovery speed and poor economic benefit,the distribution characteristics of remaining oil are analyzed based on summarizing reservoir characteristics(lithological,physical and fluid characteristics),development process and current development situation,and the screening criteria for improving oil recovery are compared with the experimental characteristics of reservoirs and electric logging.Explain permeability,pore throat size statistics,mercury injection experiments and so on,and prove that Yan101-2 reservoir in B area of M oilfield is suitable for poly-surfactant binary flooding.In view of the high salinity of formation water in Yan101-2 area B of M oilfield,salt-resistant polymer 3640C with special groups was selected and its basic properties(molecular weight matching with throat radius,cohesion and shear resistance)were determined to determine the suitable molecular weight and mass fraction of polymer.The oil-water interfacial tension of five surfactants(SDBS,ABS,APEO,HDS,BS)and the interfacial tension of polymer(3640C)compounded with surfactant were compared.The binary systems of poly-surfactant were initially screened as SDBS/3640C,APEO/3640C and HDS/3640C.Further,through the aging experiment of binary system of poly-surfactant(1-90 days),the viscosity and interfacial tension of the system were measured,and two kinds of composite flooding systems(HDS/3640C and APEO/3640C)with good synergy and stability were selected.The emulsifying properties of HDS/3640C and APEO/3640C were compared in terms of emulsifying rate,water evolution rate and emulsion stability.The binary system of poly-surfactant was finally determined to be HDS/3640C.Using the core of B area of M oilfield,the percolation characteristic experiment of composite flooding system was carried out to study the injectability,fluidity control ability and propagation of HDS/3640C,and the enhanced recovery ability of HDS/3640C was studied through indoor oil displacement experiment,and the appropriate concentration of surfactant was determined.At last,the enhanced oil recovery capability of HDS/3640C and APEO/3640C systems is compared under microscopic conditions,and the positive influence of emulsification on oil displacement effect is analyzed.The results show that the optimum system for Yan 101-2 reservoir in B area of M oilfield is 0.24%HDS+0.12%3640C,and the oil recovery can be increased by 23.53%in laboratory test.