Study of downhole heating based on ultrasonic cavitation effect

Aiming at the problems of heating the well chamber and preventing the wellbore from freezing in winter, a technology based on the ultrasonic cavitation effect is proposed, which has better operational efficiency and safety than the traditional technology. Taking the Wangzhuang North Chestnut air shaft as an example, the heat equation of the incoming air was established to obtain the heating capacity Q of 4 351 860.77 kJ/h. Further, the heating fan was utilised to achieve the downhole heat supply. Firstly, the design process of ultrasonic heating fan system is determined, the 2D model of the fan is established, and the fan process diagram is given. Based on the theory of ultrasonic cavitation effect and the amount of heating Q, the ultrasonic parameters of the ultrasonic heating array design link are defined to obtain the ultrasonic frequency of 65 kHz, the total power of 1200 kW, and the single power of 200 kW. Temperature simulations were carried out using the CFD tool of MATLAB to effectively verify the heating effect of the proposed heating technology. Finally, by comparing and analysing the proposed heating technology with the traditional heating technology, it is concluded that the ultrasonic hot air heating technology has obvious advantages in terms of thermal efficiency, energy saving and environmental protection.