Investigation On Oil Displacement Mechanism Of Polymeric Surfactant For Conventional Heavy Oil

Polymeric surfactant is a kind of multifunctional oil displacement agent,which takes acrylamide hydrocarbon chain as the skeleton and introduces functional groups with different functions through graft copolymerization.Its molecule has a chain structure that thickens the aqueous phase and an active group that reduces the viscosity of the oil phase,so it has the characteristics of both polymer and surfactant.Although a great quantity of experimental investigation have been carried out by scholars at home and abroad on polymeric surfactant,there are few discuss on the oil displacement performance and mechanism for conventional heavy oil.The chief aim of this paper work is to reveal the oil displacement mechanism of polymeric surfactant for conventional heavy oil by physical simulation and numerical simulation experimental methods.Firstly,the distribution morphology in solution,enhancing viscosity property,viscoelasticity,emulsification and viscosity reduction and oil-water interfacial tension reduction ability of the polymeric surfactant were investigated by microscopic analysis and rheological experiments.Secondly,through the sand packed flooding experiment,the author demonstrate the ability of the oil displacement performance of polymeric surfactant and compared with polymer,surfactant and polymer-surfactant compound system.Thirdly,through the microscopic visualization flooding experiments and combined with the performance evaluation results of the polymeric surfactant,the oil displacement mechanism of the polymeric surfactant for conventional heavy oil was present.Finally,through the experimental method of reservoir numerical simulation,the injection parameters of polymeric surfactant are optimized.Through microscopic analysis and rheological experiments,the results of the experiment indicate that the microscopic network structure of the polymeric surfactant in the solution distribution is denser than HPAM solution at the same concentration,and enhancing aqueous phase viscosity property is better than HPAM.That is,the viscosity of the polymeric surfactant solution is 1.6 to 2.5 times of HPAM with the same concentration.Through the emulsification experiment of polymeric surfactant with heavy oil,the author came to realize that the polymeric surfactant solution can "cutting" the heavy oil and the continuous oil phase is divided into flakes and strips.When the water-oil ratio reached 7:3,the viscosity reduction rate of the polymeric surfactant solution for heavy oil/watered heavy oil reaches more than 90%.Through the sand packed flooding experiment,it is proved that injection of 0.5 PV and 0.2%polymeric surfactant solution can enhanced heavy oil recovery by 13.5%,4.7% and 8.2%respectively,compared with pure water flooding,polymer flooding with the same viscosity and surfactant flooding with the same concentration.The polymeric surfactant solution with 0.5 PV injection volume and 0.2 % concentration can enhance oil recovery by 13.5 % on the basis of water flooding.Through the microscopic visualization oil displacement experiment,this fruitful work gives explanation of oil displacement mechanism of the polymeric surfactant for conventional heavy oil,that is,increasing sweep efficiency and enhancing emulsifying capacity.Finally,we have carried out several numerical simulation experiments to simulate polymeric surfactant flooding in the conceptual model of conventional heavy oil reservoir,it shows that the effect of polymeric surfactant flooding is better at the early development stage.The recommended injection concentration is greater than 0.3 % and the injection volume is greater than 0.4 PV.