Abstract: An ultrasonic energy producing device for reducing the viscosity of oil in an oil well. The device includes: an electroacoustic transducer for converting an alternating electrical power signal at a selected voltage into acoustic energy, the transducer being arranged to be disposed in acoustic communication with oil present in the well; a source of alternating electrical power at a voltage substantially higher than the selected voltage, the source being arranged to be disposed at ground level adjacent the well; and an electrical conductor of a length sufficient to extend from ground level to at least the level of oil in the well for conducting alternating electrical power from the source to the transducer.