Evaluating Phase Blockages and Mobility Changes During Pressure Transient Analysis

Pressure transient analysis (PTA) is a cogent methodology to evaluate dynamics of hydrocarbon reservoirs. Numerous analytical and numerical models have been developed to model various types of wellbore, reservoir, and boundary responses. However, the near-wellbore region remains to be perplexing in pressure transient analysis. In this paper we investigate the pressure transient behavior of phase blocking and mobility variations caused by fluid phase interactions or properties, such as viscous drag forces and surface tension at the near-wellbore region and their impact on pressure transient evaluation. We have used real field examples to scrutinize relative effects of mobility variations in pressure transients. The impact of capillary number (Nc) acting on the near-wellbore region and its influence on pressure transient behavior and skin alteration were examined in detail. Several real field examples honoring actual reservoir rock special core analysis (SCAL) and fluid pressure/volume/temperature (PVT) properties have been studied. Actual field data discussed in this paper for PTA were captured during drill stem testing (DST) operations from various hydrocarbon reservoirs in the Berkine Basin of Algeria. PVT laboratory-measurement-based fluid properties were used in conjunction with tuned equation of state (EOS) models to ensure consistency between wells and reservoirs. Pressure transient analysis of a gas condensate reservoir system can depict various mobility regions, especially while flowing below dew point pressure. In some cases, three-distinct-mobility regions can be identified as: a far-field zone with initial gas and condensate saturation; a mid-field zone with increased condensate saturation and lower gas relative permeability; and a near-wellbore zone with high Nc which increases gas relative permeability and mobility. These three-distinct-mobility regions form due to condensate dropping out and fluid interactions in the near wellbore. We demonstrate, with real-life field examples of the near-wellbore region, how the relative effects of viscous drag forces and surface tension forces acting across the liquid and gas interface can enable the reference fluid phase to regain its mobility. We further investigate the evaluation of skin factor in such circumstances and show how the existence of phase blocking and velocity stripping can cause over-estimation or under-estimation of skin factor. We present a novel set of real field examples and relations between various zones in hydrocarbon reservoirs to avoid snags of misleading pressure transient interpretations and how composite models can be accurately used to represent complex cases. Field examples from Algerian hydrocarbon reservoirs are depicted. The findings could be easily applied for similar reservoirs in other parts of the globe to identify and model such intricate systems.

Design and Optimization of Microwave Sensor for the Non-Contact Measurement of Pure Dielectric Materials

This article presents an optimized microwave sensor for the non-contact measurement of complex permittivity and material thickness. The layout of the proposed sensor comprises the parallel combination of an interdigital capacitor (IDC) loaded at the center of the symmetrical differential bridge-type inductor fabricated on an RF-35 substrate (εr = 3.5 and tanδ = 0.0018). The bridge-type differential inductor is introduced to obtain a maximum inductance value with high quality (Q) factor and low tunable resonant frequency. The central IDC structure is configured as a spur-line structure to create a high-intensity coupled electric field (e-field) zone, which significantly interacts with the materials under test (MUTs), resulting in an increased sensitivity. The proposed sensor prototype with optimized parameters generates a resonant frequency at 1.38 GHz for measuring the complex permittivity and material thickness. The experimental results indicated that the resonant frequency of the designed sensor revealed high sensitivities of 41 MHz/mm for thickness with a linear response (r2 = 0.91567), and 53 MHz/Δεr for permittivity with a linear response (r2 = 0.98903). The maximum error ratio for measuring MUTs with a high gap of 0.3 mm between the testing sample and resonator is 6.52%. The presented performance of the proposed sensor authenticates its application in the non-contact measurement of samples based on complex permittivity and thickness.

The optical and electrical non-invasive methods of measurement for glucose concentration in biological liquids

The article describes the radio-wave and optical methods of determining glucose concentration. The radio-wave method is based on the use of a sensor with a resonant frequency that is displayed when in contact with highly lossy materials and with an extended near-field zone in the resonance area. The optical method is based on studying the influence of glucose concentration (0–20 mmol/l) in bidistilled water on absorption spectra in the range of 190-1000 nm. The article presents the results of the experimental test of the near-field sensor with the pre-produced biological media imitating the human body tissues, and the results of the optical method demonstrate the possibility to measure the concentration with the use of an optical emitter with a wave length of 830 nm.

COMPARISON OF THE CHARACTERISTICS OF THE CORRELATION-INTERFEROMETRIC BELLOWS WHEN USING DIRECTIONAL AND NON-DIRECTIONAL ANTENNA ELEMENTS

При создании корреляционно-фазовых пеленгаторов, как правило, в качестве антенных элементов используют ненаправленные антенные элементы (АЭ). Для использования измерений направленных АЭ требуется модифицировать алгоритмы пеленгации. Представлены соответствующие модификации алгоритмов и проведено сравнительное исследование точности пеленгования применительно к двухканальным корреляционно-интерферометрическим стандартным пеленгаторам, использующим плоские антенные решетки из направленных и ненаправленных АЭ. Рассмотрена также возможность определения пеленгов лишь по энергетическим измерениям, отсутствующая применительно к пеленгаторам с ненаправленными АЭ. Показано, что применение направленных АЭ позволяет снизить вероятность возникновения аномальных ошибок, повысить точность пеленгования при существенно больших значениях угла места, определяющего направление на источник радиоизлучения, снизить негативное влияние отказа от учета сферичности приходящей волны и, следовательно, уменьшить размеры ближней зоны пеленгатора, для которой характерно появление аномальных ошибок пеленгования. В многосигнальной радиообстановке использование направленных свойств АЭ позволяет также формировать пеленгационную диаграмму, обеспечивающую частичное подавление помеховых сигналов. Вместе с тем эффективное использование направленных свойств антенных АЭ требует максимально точного учета их диаграмм направленности (ДН). Погрешности описания ДН могут приводить к заметным ошибкам при определении пеленга, поэтому повышение качества работы пеленгационной системы за счет использования направленных АЭ сопровождается повышением требований к определению и точности практической реализации ДН АЭ When creating correlation-phase direction finders, as a rule, non-directional antenna elements (AE) are used. To use directional AE measurements, it is necessary to modify the direction finding algorithms. We present the corresponding modifications of the algorithms and we carried out a comparative study of the direction finding accuracy in relation to two-channel correlation-interferometric standard direction finders using flat antenna arrays of directional and non-directional AEs. We also considered the possibility of determining bearings only from energy measurements, which is absent in relation to direction finders with nondirectional AE. We show that the use of directional AEs makes it possible to reduce the probability of occurrence of anomalous errors, to increase the accuracy of direction finding at significantly large values of the elevation angle, which determines the direction to the radio emission source, to reduce the negative effect of refusing to take into account the sphericity of the incoming wave and, consequently, to reduce the size of the near-field zone of a bearer, which is characterized by the appearance of abnormal direction finding errors. In a multi-signal radio environment, the use of the directional properties of the AE also makes it possible to form a direction finding diagram that provides partial suppression of interference signals. At the same time, the effective use of the directional properties of antenna AEs requires the most accurate consideration of their directional patterns (DP). Errors in the description of the pattern can lead to noticeable errors in determining the bearing, therefore, improving the quality of operation of the direction finding system due to the use of directional AEs is accompanied by increased requirements for the determination and accuracy of practical implementation of the pattern of AE

Development of Generic Radiating Model for Rectangular Capacitors: Magnetic Near Fields Analysis and Modeling

This chapter deals with modeling the radiation from rectangular film capacitors as a power electronics component. The rectangular film capacitors are sources of electromagnetic radiation, where its characterization is crucial for electronic circuits EMC. Our study presents the analyses and modeling of the magnetic near field radiated by the plastic and the polyester capacitors. An electromagnetic inverse method is combined with an optimization method based on genetic algorithms to create a radiating equivalent model. A very good agreement is observed between the magnetic near field cartography measured above the studied structure and calculated using the developed model parameters. Finally, a generic radiating model is proposed for various types of rectangular film capacitors. The generic model is validated using the measurements on a rectangular capacitor. The obtained equivalent model can calculate the magnetic field at any near field zone and far field around the capacitors. Circuit designers can use the field distribution to optimize the placement of the capacitors on the printed circuit board to reduce their coupling and potential interaction with other equipment in the vicinity of the system.

Are there bound states in the continuum in a dielectric ring?

Trapping and confining electromagnetic waves is important in both basic research and a variety of applications. For these purposes, various physical mechanisms are exploited including bound states in the continuum, which have been actively investigated recently. Bound states in the continuum have been observed in various objects consisting of both one and a number of dielectric structures. In particular, these photonic states were observed in high-contrast dielectric cylinders in the regime of strong eigenmode coupling, which leads to destructive interference in the far-field zone. In this article, we present the results of a study of bound states in a continuum in a dielectric ring, i.e. cylinder with coaxial air hole. The dependence of the quality factor Q on the normalized diameter of the hole is discussed.

Adhoc mobile power connectivity using a wireless power transmission grid

Wireless charging of devices has significant outcomes for mobile devices, IoT devices and wearables. Existing technologies consider using Point to Point type wireless transfer from a transmitter Tx (node that is sending Power) to a receiver Rx (node that receives power), which limits the area of coverage for devices. As a result, existing systems are forced to use near field coupling to charge such devices. Fundamental limitation is also that such methods limit charging to a small hotspot. In partnership with Wireless Electrical Grid LANs (WiGL pronounced “wiggle”), we demonstrate patented Ad-hoc mesh networking method(s) to provide wireless recharging at over 5 feet from the source, while allowing significant lateral movement of the receiver on the WiGL (Wireless Grid LAN or local area network). The transmitter network method leverages a series of panels, operating as a mesh of transmitters that can be miniaturized or hidden in walls or furniture for an ergonomic use. This disruptive technology holds the unique advantage of being able to provide recharging of moving targets similar to the cellular concept used in WiLAN, as opposed to prior wireless charging attempts, which only allow a hotspot-based charging. Specifically, we demonstrate the charging of a popular smartphone using the proposed system in the radiating near field zone of the transmitter antennas, while the user is free to move in the space on the meshed network. The averaged received power of 10 dBm is demonstrated using 1W RF-transmitter(s), operating in the 2.4 GHz ISM band. The proposed hardware consists of antennas arrays, rectennas, power management and USB 2.0 interfaces for maintaining a voltage between 4.2 and 5.3 V and smooth charging. We also show extending the wireless grid coverage with the use of multiple transmitting antennas, and mechanical beam-steering even further an increased coverage using the proposed system.

Bound states in the continuum in strong-coupling and weak-coupling regimes under the cylinder – ring transition

Bound states in the continuum (BIC) have been at the forefront of research in optics and photonics over the past decade. It is of great interest to study the effects associated with quasi-BICs in the simplest structures, where quasi-BICs are very pronounced. An example is a dielectric cylinder, and in a number of works, quasi-BICs have been studied both in single cylinders and in structures composed of cylinders. In this work, we studied the properties of quasi-BICs during the transition from a homogeneous dielectric cylinder in an air environment to a ring with narrow walls while increasing the diameter of the inner air cylinder gradually. The results demonstrate the quasi-BIC crossover from the strong-coupling to the weak-coupling regime, which manifests itself in the transition from the avoided crossing of branches to their intersection with the quasi-BIC being preserved on only one straight branch. In the regime of strong-coupling and quasi-BIC, three waves interfere in the far-field zone: two waves corresponding to the resonant modes of the structure and the wave scattered by the structure as a whole. The validity of the Fano resonance concept is discussed since it describes the interference of only two waves under weak coupling conditions.