Increasing the Penetration Depth of Microwave Radiation Using Acoustic Stress to Trigger Piezoelectricity

Abstract

Electromagnetic waves as a mechanism of heat generation in the reservoir is a concept that has great potential to efficiently produce heavy oil and bitumen. However, as a result of large wave attenuation, the penetration depth of the wave is relatively small. This limits the economic viability of an otherwise technically proven technology. Taking advantage of the inherent piezoelectric phenomenon in quartz crystals enables the manipulation of the penetration depth of the wave. Acoustic waves were introduced simultaneously with a microwave to the core samples where the presence of the mechanical wave generated an infinitesimal stress. Mechanical stress achieved by the acoustic wave triggered piezoelectricity in two sandstone samples with a limestone sample serving as the control. All consolidated core samples were fully saturated with either oil or water to capture the effect of the pore space. The incremental stress manifests itself through change in the complex permittivity of the sample measured with a vector network analyzer. The penetration depth of the microwave was calculated as a function of the measured complex permittivity. Comparative analysis of the penetration depth of the varying imposed stress states illustrates the additive penetration achieved due to piezoelectricity. Piezoelectricity as the fundamental mechanism of penetration increase was further demonstrated by isolation of the quartz contribution through use of the limestone. Increase in penetration depth was realized for all oil-saturated sandstone cores. The presence of the acoustic wave introduced a stress component across the quartz crystals, generating a change in the electric potential. This created a dynamic polarization that corresponded to an absorption environment more conducive to microwave penetration.

Impact of Microwaves on Organic Synthesis and Strategies toward Flow Processes and Scaling Up

“…The attenuation of the electromagnetic wave, measured at a small penetration depth of the most adsorbing solvent, is another limitation of MW irradiation when large-scale synthesis is studied. Different approaches have been pursued to overcome this limitation, and the combination of MW irradiation with acoustic waves (ultrasound) may help generate an increase in the penetration depth beyond intensifying the mixing and mass transfer. , The mechanical stirring would yield volumetric heating, and an example of a large-scale MW batch reactor devoted to synthesis has been described …”

“…Different approaches have been pursued to overcome this limitation, and the combination of MW irradiation with acoustic waves (ultrasound) may help generate an increase in the penetration depth beyond intensifying the mixing and mass transfer. 14,15 The mechanical stirring would yield volumetric heating, and an example of a large-scale MW batch reactor devoted to synthesis has been described. 16 Understanding how the MW deployment can enhance the reaction rates in organic synthesis requires a good background with knowledge of MW interactions with matter and other fundamentals.…”

Microwave and Ultrasound Based Methods in Sludge Treatment: A Review

“…Athermal effects are induced by the change in dipole orientation of certain polar molecules, which increase the possibility of breaking down the hydrogen bonds of biopolymers (polysaccharides, proteins, DNA, RNA) [30,31]. In industrial use, a frequency of 915 MHz is the most favourable, since shorter frequencies have higher penetration depth [32], thus increasing the extent of thermal and athermal effects.…”

A Pore-Scale Model for Dispersion and Mass Transfer during Acoustically Assisted Miscible Displacements in Porous Media

“…Although acoustic waves cannot directly interact with electromagnetic waves, the two phenomena can interact indirectly when they share a piezoelectric medium, which can generate internal electrical charges by applying mechanical stress. Based on Morte et al, 24 the inherent piezoelectric phenomenon in quartz, which is a component of sandstone, can trigger such interaction in porous media.…”