Comprehensive Review: Research and Application of Microwave Heating Technology in In Situ Exploitation of Oil Shale

Oil shale is a rich unconventional energy source that has not been valued in the past due to its high mining costs and low economic benefits. However, with the gradual depletion of conventional crude oil resources, the economic value of oil shale has become increasingly significant. Microwave heating technology, with its efficient energy conversion and good penetration, has become a strong candidate for in situ oil shale mining. For example, studies have shown that microwave heating can achieve a heating efficiency of up to 80% in certain oil shale samples, which is significantly higher than that of traditional methods such as conduction heating (around 50%) and convection heating (around 60%). However, comprehensive reviews on the application of microwave heating technology in oil shale in situ mining are still rare. This review systematically reviews the application progress of microwave heating technology in in situ oil shale mining, including microwave heating devices, dielectric properties of oil shale, numerical simulation techniques, and methods for improving heating efficiency. The research found that optimizing microwave frequency, improving magnetron design, and adding microwave absorbers can significantly improve the heating efficiency and uniformity. In addition, the technology is also environmentally friendly and can achieve crude oil cracking and desulfurization under the action of a catalyst, improving the quality of the crude oil.