Application of a novel foamed fracturing fluid to the oil shale exploitation based on microwave heating

In order to prove the feasibility of the microwave heating based in-situ exploitation of oil shale, it was proposed to take the novel fracturing fluid containing nano-particles as the working fluid for the microwave heating based in-situ exploitation of oil shale. In addition, the properties of the working fluid were investigated and the pyrolysis products were analyzed. It is indicated that foamed fracturing fluid is superior to water based fracturing fluid in term of energy saving. The temperature field of oil shale was measured, and it is shown that nano-particle of ferric oxide can increase the microwave heating efficiency effectively. The half life and foam microstructure were analyzed, and it is shown that nano-particle of ferric oxide can increase the stability of foamed fracturing fluid to some extent. It is revealed by means of stereomicroscope and environmental scanning microscope that the injection of foamed fracturing fluid brings slight damage to oil shale, but due to the thermal decomposition of surfactant, the conversion of kerogen and the microfractures induced by the microwave heating after the heating, the pores in oil shale cores cannot be blocked by nano-particles of ferric oxide. Finally, the pyrolysis products were analyzed by conducting the experiments of elemental analysis, four-component analysis, gas chromatography-mass spectrography and X-ray diffraction. And it is indicated that the non-heat effect of microwave promotes the generation of light hydrocarbon while more sulfur and nitrogen compounds are released in the form of gas.