The main method of high-viscosity oil production is heating, but there are difficulties in delivering heat to the formation and distributing this heat there quite evenly. The existing methods of delivering heat to the formation are often ineffective – small heat coverage area, excessively high temperatures in some places, loss of a large amount of heat from the wellhead to the bottomhole, need for large areas around the well for thermal action. Combined electromagnetic-acoustic action with the injection of solvent onto the formation could significantly increase the effectiveness of formation heating. The study solves the problem of finding a temperature field with a two-stage effect on the formation: electromagnetic-acoustic heating and then pumping solvent into the formation in order to increase the radius of coverage with thermal impact. With this setting of the problem, the resulting mathematical model does not have an analytical solution. A numerical solution using the finite difference method with an implicit scheme gives fairly accurate results.