The analysis of the current in situ oil shale mining
technology
shows that oil shale has the characteristic of poor thermal conductivity.
Too solve the problems of low efficiency and high cost of traditional
heat conduction mining methods, the microwave mining of oil shale
has good production prospects. By microwave heating, electromagnetic
energy is directly converted into heat energy by acting on medium
molecules. Its transmission property makes the material inside and
outside the medium simultaneously heated. No heat transfer is required.
This paper summarizes the mechanism of the microwave pyrolysis of
oil shale, pyrolysis parameters, and changes in the structure of
oil shale in microwave pyrolysis, and how the addition of a microwave
absorber endows the microwave with a better heating effect. At present,
the absorbents used in microwave heating of oil shale are ferrite
absorbents, nanometal absorbents, semicoke, and graphite. The research
of ferrite microwave absorbents has been developing toward modification
and nanocrystallization by adding trace elements. Among them, the
microwave of nanoparticles leads to good absorption performance, which
can help microwaves realize high-temperature conversion of oil shale.
Microwaves can also be used with fracturing fluids. In the future,
the structure and absorption relationship can be improved to achieve
better results. Semicoke produces a strong eddy current in the microwave
field and has a high-temperature rise rate. Using semicoke as a microwave
absorbent can make semicoke waste into a treasure with efficient comprehensive
utilization. In addition, the numerical simulation of oil shale microwave
pyrolysis is also of great significance. Simulation can create reservoir
conditions that experiments cannot reach. At present, it mainly simulates
temperature field, decomposition, and product distribution of kerogen,
and porosity and permeability evolution of oil shale. In the simulation
of adding absorbent, the heating effect of adding nano-Fe3O4 absorbent is better than that of not adding absorbent,
and its microwave heating range is also larger. But at present, there
are few simulations for this aspect. The experimental research and
numerical simulation of oil shale microwave pyrolysis absorbent need
further exploration in the future.