This paper studies theoretically the process of electromagnetic wave scattering E- and H- polarizations of a dissipative oil film, covering the seawater. Reflectance-over-incident power values are studied analytically and numerically. Such conditions are formulated, at which the principal microwave power penetrates the oil well and seawater. The power analysis is made in the considered system. The share of incident radiation power, absorbed in the oil film (oil film heating efficiency), is determined. An analysis is made of the ratio of microwave power, used for oil film heating, to that, absorbed in the adjacent seawater layer. A study is made on the heat release power density distribution in the oil film and seawater.