Research On Formation And Displacement Mechanism Of Small Molecule Viscoelastic Fluid

In recent years,most of China's old oil fields go into a high water period or high water level,the annual decline in production is serious,the old oil field development is very serious.Tertiary oil recovery uses a variety of chemicals to improve the flooding medium diffusion coefficient and wash oil efficiency,the maximum increase in crude oil recovery rate is about30%,which for the old oil field is of great significance.Viscoelastic surfactants have high viscosity at a certain concentration,have a certain degree of flow control,and have the ability to reduce the interfacial tension of oil and water,which is expected to be a good oil exporter.Using the complex system of amphoteric surfactant HDPS and anionic surfactant SDS to construct the wormlike micellar system under the condition of high salinity of the simulated strata,the phase behavior,rheological properties and reducing oil/water interfacial tension properts,and the use of complex system for indoor simulation displacement operations,in order to analyze the small molecule viscoelastic system in all aspects of performance and oil displacement efficiency.The results show that the small molecule viscoelastic fluid has effect on controlling the flow and reducing the interfacial tension of the oil and water,and it is more than 20%of the oil recovery on the basis of water flooding to reach the composite composed of polymer,surfactant and alkali System of oil displacement effect.1500mg L^-1HPAM/HDPS-SDS system can enhance the efficiency of washing oil,increase the viscosity of the system and enhance the ability of fluid control,so the effect of improving oil recovery is remarkable.In addition,the viscosity of the system was significantly reduced when the concentration of 1500mg L^-1HPOC/HDPS-SDS was low at the low surfactant concentration,and the effect of improving the recovery efficiency was improved.In the case of high surfactant concentration,After the bundle,the viscosity of the system and the increase of the concentration of the surfactant are beneficial to improve the recovery rate,thus the effect of improving the recovery efficiency is significantly increased.