Abstract: Bohai SZ36-1 oilfield is viscous oilfield, with high density, high viscosity, high content of colloid and asphaltene. With traditional thermal well washing technology individually, a large number of geothermal water should be used for a long time to clean the wellbore, resulting in waste of resources and pollution of formation. Therefore, the chemical synergy thermal well-washing technology is put forward. Through laboratory research and numerous applications on offshore platforms, good results have been achieved, reducing the operation time and oil recovery cycle, and increasing oil production. This method can also be used for well flushing and paraffin removal in other viscous oilfield.