Abstract:

Microwave heating technology as an alternative to conventional heating methods in oil shale exploitation microwave heating technology has gained significant attention as an alternative to traditional heating methods in the exploitation of oil shale reserves. In order to investigate the thermal response of oil shale under microwave radiation, as well as the changes in porosity, permeability, and internal displacement, numerical simulations were conducted using COMSOL Multiphysics software. These simulations were based on a coupled 3D electromagnetic-thermal-permeability-solid mechanics model. The results revealed the following key findings: Under microwave heating conditions, the temperature of the oil shale reservoir increases rapidly. Moreover, as the microwave power increases, the rate of temperature rise significantly accelerates. Different power levels result in distinct timeframes required for the reservoir to reach its pyrolysis temperature, with the fastest heating occurring at 800 W microwave power. With prolonged heating, porosity and permeability gradually increase, especially at higher power levels, where the growth is more pronounced. At the 500th day of microwave irradiation, the average permeability of oil shale reached its peak under different power levels, with a permeability of 1.93×10-16 m2 observed at 800 W. Microwave heating leads to the weakening of mechanical properties and increased formation damage in the reservoir. When the microwave radiation power reaches 800 W, the maximum displacement reaches 3.8 cm. In summary, selecting a microwave power of 600 W demonstrates significant engineering application benefits for the in-situ pyrolysis of oil shale reservoirs.

Key words: oil shale, microwave heating, reservoirs, numerical simulation, in-situ extraction