Research On Enhanced Oil Recovery By Solvent System With Steam Injection In Heavy Oil Reservoir

High viscosity, high threshold pressure and poor flow ability are the main characteristic of Extra-heavy oil. The waiting for resolving problem is how to economically and high efficiency exploit Extra-heavy oil in Shengli oil field. Steam injection is the effective technology to produce heavy oil. However, it is difficult to obtain good results only with steam injection for the Extra-heavy oil reservoir.If the solvent is added with steam, the solvent can spread in the oil zone and dissolve asphaltene and resin, thereby decrease oil viscosity, increase the oil mobility, decrease threshold pressure and attain to the required demand of steam injection program. On the base of the investigation of inland and abroad, the paper make a study of solvent at the meantime steam injection in enhanced oil recovery according to laboratory experiments.Based on the experiments, the disperse washing oil visbreaking solvent system was developed. It has the behavior of strong effect of dissolving the asphaltene and resin, good effect to reducing the viscosity and good disperse in oil. If add 5 percent solvent to the oil, the viscosity reducing ratio is 68.86%; if add 10 percent solvent to the oil, the viscosity reducing ratio is 89.39%.Based on the displacement characteristics in physical modeling, solvent with steam injection can obviously enhanced displacement efficiency, increase initial production and decrease displacement pressure, thereby decrease steam injection pressure and increase exploitation emotion of steam injection. The displacement efficiency of solvent with steam injection is three times that of pure steam injection. The initial displacement pressure of solvent with steam injection is only one percent three that of pure steam injection.