Analysis of factors affecting microwave heating of natural gas hydrate combined with numerical simulation method

Abstract

As a clean and abundant unconventional natural gas resource, natural gas hydrate (NGH) holds the characteristics of safety, high efficiency and sustainable exploitation, which helps to alleviate the energy shortage of China, reduce the foreign-trade dependence of oil and gas, and ensure the national energy security. Microwave heating is a significant method that has been used in natural gas hydrate exploration. By using the microwave heating, the NGH in the reservoir formations would be heated, decomposed and stimulated thanks to taking advantage of microwave heating's unique characters: efficiency, high speed, clean and pollution-free. This paper established the temperature under microwave heating gas hydrate distribution theory model, and by using the finite element method for simulating temperature field of microwave heating gas hydrate, this paper analyzed the natural gas hydrate in the microwave field temperature distribution in the influencing factors. Microwave has a significant heating effect on the hydrate reservoir in the immediate vicinity of wellbore, and it is not affected by the initial conditions of reservoir. The temperature can rise to above 50°C within 1 h which is higher than the phase equilibrium temperature at the time of hydrate decomposition and is helpful to improve the decomposition rate of hydrate. The frequency is set at 915 MHz, and the feed port has a spiral arrangement with a length of 10 mm, which greatly expands the microwave heating range.