Viscosity-reducing oil-displacing agent for viscosity-reducing combination flooding of common heavy oil reservoir as well as preparation method and application thereof

The invention provides a viscosity-reducing oil-displacing agent for viscosity-reducing combination flooding of a common heavy oil reservoir as well as a preparation method and application of the viscosity-reducing oil-displacing agent, and belongs to the field of oilfield chemistry. The viscosity-reducing oil-displacing agent for viscosity-reducing combination flooding of the common heavy oil reservoir, provided by the invention, comprises the following components in percentage by mass: 30-40% of a nano viscosity reducer, 10-20% of isopropanolamide, 5-10% of imidazoline, 10% of low-carbon alcohol and the balance of water. The viscosity-reducing oil-displacing agent provided by the invention is mainly applied to viscosity-reducing combination flooding of a common heavy oil reservoir, and by compounding with a polymer, the dual effects of viscosity-reducing chemical flooding and polymer flooding are exerted, so that the viscosity-reducing oil-displacing agent not only can reduce the viscosity and wash oil, but