Research On Relative Permeability Curve Characteristics And Displacement Mechanism Of Heavy Oil Alkali/Surfactant Flooding

Thermochemical flooding is still in the demonstration stage as a subsequent measure of thermal recovery in ultra-high heavy oil reservoirs.The relative permeability curve reflects the flow of oil displacing agent and crude oil in porous media and is an important material in reservoir development.In the process of heavy chemical thermal chemical flooding,after the injection of hot fluid,the reservoir rock and fluid properties will change,resulting in changes in the flow pattern of heavy oil and water.It is very difficult to obtain accurate and representative thermochemical relative permeability curves.Based on the theoretical analysis,this paper researches the hot water,alkaline water and surfactant/viscosity agent displacement process under different temperature and different oil displacing agent concentrations through physical simulation displacement experiments.The relative permeability of oil and water was measured,and the effects of temperature and oil displacing agent concentration on the relative permeability curve characteristics and oil displacement efficiency were analyzed.For the data processing of high-temperature relative permeability of heavy oil,firstly,the water flooding experiment in the pipeline was carried out to accurately calculate the dead volume of the pipeline.Then,the mathematical method was programmed to automatically select different interpolation or fitting methods to accurately characterize mathematical relationship between cumulative oil production and cumulative liquid production,avoiding the occurrence of abnormal points of the relative permeability curve in the JBN method.The experimental results show that the temperature and the concentration of the oil displacing agent have a great influence on the relative permeability curve of the heavy oil/ultra-high heavy oil thermochemical flooding.The oil phase relative permeability curve increases with the temperature,the alkali mass fraction and the surfactant.As the mass fraction increases,the relative permeability of the aqueous phase increases with increasing temperature,but decreases with the increase of the alkali mass fraction and the surfactant mass fraction at the same temperature.The ultimate recovery increased with increasing temperature and increased with the increase in alkali mass fraction and surfactant mass fraction at the same temperature.The combined action of the W/O emulsion in the heavy oil/ultra-high heavy oil caustic flooding,the W/O/W emulsion and the large particle size O/W emulsion formed in the surfactant flooding resulted in an increase in recovery.