Electromagnetic-heating enhancement of source rock permeability for high recovery

Investigation of Source Rock Heating and Structural Changes in the Electromagnetic Fields Using Experimental and Mathematical Modeling

“…In addition, the effect of the electromagnetic field on the oil source rock in many cases leads to the development of stresses, fracturing, softening, and destruction of the rocks [22,23]. Thermal stresses arise as a result of the inhomogeneous thermal expansion of the rock during the heating process due to the difference in electromagnetic, thermal, and mechanical properties of minerals of rocks (quartz, feldspar, pyrite, clay and carbonates, and other).…”

Role of H2O of Gas-Bearing Shale in Its Physicochemical Properties and CH4 Adsorption Performance Alteration Due to Microwave Irradiation

“…As illustrated in Figure a, microwave irradiation promotes rapid increase in temperature of the shale matrix, therefore significantly promoting physically adsorbed CH 4 desorption from shale. , Furthermore, microwave irradiation decreases adsorption pores for accommodating CH 4 of the dry shale matrix with a diameter below 10 nm, while it increases meso- and macropores with a diameter greater than 10 nm (Figure b) . Such transformation in full-scale pores of a dry shale matrix can not only promote CH 4 desorption but also strengthen diffusion capability of previously desorbed CH 4 within gas-bearing shale reservoirs. , In addition, the shale matrix contains a wide variety of inorganic minerals mainly including nonclay minerals, such as quartz, pyrite, calcite, feldspar, dolomite, and plagioclase, and clay minerals, such as illite and smectite. , The dielectric properties of typical inorganic materials of shale are listed in Table . , As shown in eq , the dielectric constant is measured by the real part of relative permittivity, indicating how much energy can be stored in the material, and by the loss factor, that is, the imaginary part of the relative permittivity, indicating the ability of converting the stored energy into heat. Among these minerals, pyrite, illite, and smectite with a greater dielectric constant and loss factor always show better microwave heating performance .…”

“…Provided that the generated thermal stress exceeds mechanical strength of inorganic minerals, fracture will appear within the shale matrix and further increase shale reservoir permeability (Figure 1c), 27−29 thereby making CH 4 flow within the reservoir more easily. 21 Overall, microwave irradiation has capability of enhancing desorption, diffusion, and flow performance of CH 4 within the shale reservoir. Thus, the aforementioned advantages make microwave irradiation become a viable option to enhance shale gas recovery.…”

“…Given the difference in the dielectric constant and loss factor among various kinds of inorganic minerals, thermal stress is likely to occur in the interface between different inorganic minerals or inside the same inorganic mineral. Provided that the generated thermal stress exceeds mechanical strength of inorganic minerals, fracture will appear within the shale matrix and further increase shale reservoir permeability (Figure c), − thereby making CH 4 flow within the reservoir more easily . Overall, microwave irradiation has capability of enhancing desorption, diffusion, and flow performance of CH 4 within the shale reservoir.…”

“…20 Such transformation in full-scale pores of a dry shale matrix can not only promote CH 4 desorption but also strengthen diffusion capability of previously desorbed CH 4 within gas-bearing shale reservoirs. 21,22 In addition, the shale matrix contains a wide variety of inorganic minerals mainly including nonclay minerals, such as quartz, pyrite, calcite, feldspar, dolomite, and plagioclase, and clay minerals, such as illite and smectite. 23,24 The dielectric properties of typical inorganic materials of shale are listed in Table 1.…”