Quasi-spherical cavity resonators for metrology based on the relative dielectric permittivity of gases

2004 ◽  
Vol 75 (10) ◽  
pp. 3307-3317 ◽  
Author(s):  
Eric F. May ◽  
Laurent Pitre ◽  
James B. Mehl ◽  
Michael R. Moldover ◽  
James W. Schmidt
Author(s):  
Peter Schlicht ◽  
◽  
Tianhua Zhang ◽  
Martin G. Lüling ◽  
Brita Renee Graham ◽  
...  

Natural fractures maintain a significant role in many hydrocarbon plays, in both conventional and unconventional reservoirs. In exploration and development scenarios, specific fracture properties, such as orientation and density, are important. However, more critical is their internal architecture: are the fractures open to fluid flow or filled with minerals? Borehole microresistivity imaging tools are widely used to determine these fracture characteristics. In wells drilled with water-based muds, open fractures are filled with conductive borehole fluid that enables distinguishing open, water-filled fractures from resistive, mineral-filled fractures and the surrounding rock. However, many wells today are drilled with oil-based muds. In this case, mineral-filled fractures and oil-based-mud-filled fractures are equally highly resistive and cannot be directly distinguished using resistivity images only. The latest-generation wireline oil-based-mud microresistivity imagers operate in the megahertz frequency range, radiating the electrical current capacitively through the nonconductive mud column and delivering photorealistic borehole images. Both electrical conductivity and dielectric permittivity components constitute the measured signal, from which button standoff, formation resistivity, and dielectric permittivity are inverted. Our example case shows highly resistive, high-angle fractures from the resistivity images with their orientation and density. The standoff image determines if the mud column penetrates the fracture plane, showing an apparently high standoff compared with the surrounding rock. If the standoff appears high in the fracture plane, the fracture is classified as open to fluid flow. However, are these fractures indeed fully dilated and open, or are they filled with different materials—are they partially mineralized with calcite and partially open, filled with mud? To further determine the fracture fill and susceptibility to fluid flow, a new workflow employs the material dependency of the relative dielectric permittivity. The relative permittivity is estimated as a function of resistivity and frequency pixel by pixel on the resistivity image. The estimate formula is based on several hundred laboratory measurements on core plugs with different fluid saturations and salinities. The resulting borehole image enables distinguishing materials in the volume of investigation, where low values correspond to mud-dominated oil in open fracture planes, medium values correspond to rock-forming minerals, and high values are attributed to shales and other clay-rich rocks. Fracture planes filled with patches of both low- and medium-permittivity values are classified as partially open.


Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3658
Author(s):  
María Elena de Cos Gómez ◽  
Humberto Fernández Álvarez ◽  
Alicia Flórez Berdasco ◽  
Fernando Las-Heras Andrés

An ultrathin, compact ecofriendly antenna suitable for IoT applications around 2.45 GHz is achieved as a result of exploring the use of Tencel fabric for the antenna’s design. The botanical ecofriendly Tencel is electromagnetically characterized, in terms of relative dielectric permittivity and loss tangent, in the target IoT frequency band. To explore the suitability of the Tencel, a comparison is conducted with conventionally used RO3003, with similar relative dielectric permittivity, regarding the antenna dimensions and performance. In addition, the antenna robustness under bent conditions is also analyzed by measurement. To assess the relevance of this contribution, the ultrathin ecofriendly Tencel-based antenna is compared with recently published antennas for IoT in the same band and also, with commercial half-wave dipole by performing a range test on a ZigBee-based IoT testbed.


2019 ◽  
Vol 20 (17) ◽  
pp. 4201 ◽  
Author(s):  
Bica ◽  
Bunoiu

Hybrid magnetorheological elastomers (hMREs) were manufactured based on silicone rubber, silicone oil, carbonyl iron microparticles, graphene nanoparticles and cotton fabric. Using the hMREs, flat capacitors (FCs) were made. Using the installation described in this paper, the electrical capacitance and the coefficient of dielectric losses of the hMREs were measured as a function of the intensity of the magnetic field superimposed over an alternating electric field. From the data obtained, the electrical conductivity, the relative dielectric permittivity and magnetodielectric effects are determined. It is observed that the obtained quantities are significantly influenced by the intensity of the magnetic field and the amount of graphene used.


2006 ◽  
Vol 301 ◽  
pp. 129-134 ◽  
Author(s):  
Jianyong Li ◽  
Hirofumi Kakemoto ◽  
Satoshi Wada ◽  
Takaaki Tsurumi

A new measuring method and analyzing procedure were proposed to determine the complex dielectric permittivity of materials with relatively high permittivity using an RF-impedance analyzer. Samples used for the measurement were (Ba0.6Sr0.4)TiO3 and Ba(Zr0.25Ti0.75)O3 ceramics. Micro planar electrodes were used for the measurement of complex admittance of these samples. Electromagnetic simulations were carried out for determining the relative dielectric permittivity and dielectric loss. The complex dielectric permittivity vs. frequency curves of Ba(Zr0.25Ti0.75)O3 showed a broad dielectric relaxation, while that of (Ba0.6Sr0.4)TiO3 was almost flat up to 3 GHz.


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