Feasibility Study on Downhole Gas–Liquid Separator Design and Experiment Based on the Phase Isolation Method

As oil exploitation enters its middle and late stages, formation pressure drops, and crude oil degases. In production profile logging, the presence of the gas phase will affect the initial oil–water two-phase flowmeter’s flow measurement results. In order to eliminate gas-phase interference and reduce measurement costs, we designed a downhole gas–liquid separator (DGLS) suitable for low flow, high water holdup, and high gas holdup. We based it on the phase isolation method. Using a combination of numerical simulation and fluid dynamic measurement experiments, we studied DGLS separation efficiency separately in the two cases of gas–water two-phase flow and oil–gas–water three-phase flow. Comparative analysis of the numerical simulation calculation and dynamic test results showed that: the VOF model constructed based on k−ε the equation is nearly identical to the dynamic test, and can be used to analyze DGLS separation efficiency; the numerical simulation results of the gas–water two-phase flow show that when the total flow rate is below 20 m3/d, the separation efficiency surpasses 90%. The oil–gas–water three-phase’s numerical simulation results show that the oil phase influences separation efficiency. When the total flow rate is 20 m3/d–50 m3/d and gas holdup is low, the DGLS’s separation efficiency can exceed 90%. Our experimental study on fluid dynamics measurement shows that the DGLS’s applicable range is when the gas mass is 0 m3/d~15 m3/d, and the water holdup range is 50%~100%. The research presented in this article can provide a theoretical basis for the development and design of DGLSs.

Flows of Linear Polymer Solutions and Other Suspensions of Rod-like Particles: Anisotropic Micropolar-Fluid Theory Approach

We formulate equations governing flows of suspensions of rod-like particles. Such suspensions include linear polymer solutions, FD-virus, and worm-like micelles. To take into account the particles that form and their rotation, we treat the suspension as a Cosserat continuum and apply the theory of micropolar fluids. Anisotropy of suspensions is determined through the inclusion of the microinertia tensor in the rheological constitutive equations. We check that the model is consistent with the basic principles of thermodynamics. In addition to anisotropy, the theory also captures gradient banding instability, coexistence of isotropic and nematic phases, sustained temporal oscillations of macroscopic viscosity, shear thinning and hysteresis. For the flow between two planes, we also establish that the total flow rate depends not only on the pressure gradient, but on the history of its variation as well.

Development and Validation of a Diethyl Phosphite Content in Foscarnet Sodium USP by GC MS Technique

A simple, rapid, selective, and reproducible Gas chromatographic mass spectrometry (GC-MS) method has been developed and validated for the estimation of Diethyl Phosphite content in Foscarnet Sodium USP Drug substance. The drugs were estimated using HP-5, Length-30 M, Internal diameter 0.32 mm; Film thickness 1 μ at a total flow rate of 11.9 ml/min, and column flow of 1.49 ml/min was used for the separation. Flow control mode was pressure. Column oven temperature 70°C and injector temperature 220°C. Oven program modified for proper elution of peak. The linearity range used was 0.025-0.120µg/ml and (Rt) was 6.7 min. The correlation coefficient values were found to be 0.997. Precession studies showed % RSD values less than 15.0% for all the selected concentrations. The percentage recovery of Diethyl phosphite from LOQ to 150% was found in range of 100.7 -116.7%. The content results of Phophite content were within the limits of less than 0.12 ppm. The method was validated as per the International Conference on Harmonization (ICH) guidelines. The developed method was successfully used for the quantitative analysis of commercially available dosage forms.

A novel Venturi system to generate high flow with titratable FiO2

Venturi-based flow generators are commonly used for noninvasive continuous positive airway pressure (CPAP) of high-flow nasal oxygen (HFNO). The system is simple and allows to increase the total flow while decreasing the FiO2 starting from a single oxygen source. In this report we describe the characteristics and performance of a novel Venturi system (EasyVEE, Levate, BG, Italy), which allows to vary the size of the port through which ambient air is entrained, hence allowing a continuous modulation of FiO2. The system allowed to modify FiO2 continuously between 35% and 80% and, consequently, a 1.5- to 4.5-fold increase of the total flow rate. A minimal decrease in entrainment performance was observed for positive end-expiratory pressure levels above 12.5 cmH2O. EasyVEE system appears to be a simple, flexible, and reliable solution to generate continuous flow for noninvasive respiratory support interfaces.

Development of an Innovational Multiphase X-Ray Flowmeter

Non-separation measurement of a multiphase mixture coming from an oil well is traditionally considered a complex measurement, for which rather expensive solutions are used, including non-trivial maintenance. This work aims to describe a new technology in the area of measuring multiphase oil and gas-water mixture, which is being finalized by specialists of the Tomsk Polytechnic University for conducting pilot tests at the facilities of Zarubezhneft JSC, and to indicate a more informative level of measurement of oil and gas industry production, which allows measuring the amount of oil, gas and water with high precision without the use of radioactive sources and constriction devices. The purpose of measuring a multiphase mixture is to determine the amount of oil, gas and water. In order to do this, it is required to determine the total flow rate of the mixture and the distribution of the flow by substances and phases: oil gas, oil and formation water. The total flow rate in the developed multiphase X-ray flowmeter is based on cross-correlation analysis of radiograms from two linear detectors. Measurement of the component composition for the purpose of the distribution of the flow by substances and phases is carried out by the method of two-wave absorptiometry.

3D Printed Integrated Multi-Layer Microfluidic Chips for Ultra-High Volumetric Throughput Nanoliposome Preparation

Although microfluidic approaches for liposomes preparation have been developed, fabricating microfluidic devices remains expensive and time-consuming. Also, owing to the traditional layout of microchannels, the volumetric throughput of microfluidics has been greatly limited. Herein an ultra-high volumetric throughput nanoliposome preparation method using 3D printed microfluidic chips is presented. A high-resolution projection micro stereolithography (PμSL) 3D printer is applied to produce microfluidic chips with critical dimensions of 400 µm. The microchannels of the microfluidic chip adopt a three-layer layout, achieving the total flow rate (TFR) up to 474 ml min−1, which is remarkably higher than those in the reported literature. The liposome size can be as small as 80 nm. The state of flows in microchannels and the effect of turbulence on liposome formation are explored. The experimental results demonstrate that the 3D printed integrated microfluidic chip enables ultra-high volumetric throughput nanoliposome preparation and can control size efficiently, which has great potential in targeting drug delivery systems.

Effects of water salinity on the foam dynamics for EOR application

Factors limiting foam injection for EOR application are exceptionally low rock permeability and exceedingly high salinity of the formation water. In this regard, foam formation using internal olefin sulfonate is investigated over a wide salinity range (1, 5, 8, 10, and 12% NaCl) through 10 mD limestone. The relationships between pressure drop (dP), apparent viscosity, liquid flow rate, total flow rate, salinity, foam texture, and length of foam drops at the outlet used as an indicator of viscosity are studied. Foaming is observed up to 12% NaCl, compared to a maximum of 8% NaCl in similar core-flooding experiments with 50 mD limestone and 255 mD sandstone. Thus, the salinity limit of foam formation has increased significantly due to the low permeability, which can be explained by the fact that the narrow porous system acts like a membrane with smaller holes. Compared to the increasing dP reported for highly permeable rocks, dP linearly decreases in almost the entire range of gas fraction (fg) at 1–10% NaCl. As fg increases, dP at higher total flow rate is higher at all salinities, but the magnitude of dP controls the dependence of apparent viscosity on total flow rate. Low dP is measured at 1% and 10% NaCl, and high dP is measured at 5, 8, and 12% NaCl. In the case of low dP, the apparent viscosity is higher at higher total flow rate with increasing gas fraction, but similar at two total flow rates with increasing liquid flow rate. In the case of high dP, the apparent viscosity is higher at lower total flow rate, both with an increase in the gas fraction and with an increase in the liquid flow rate. A linear correlation is found between dP or apparent viscosity and liquid flow rate, which defines it as a governing factor of foam flow and can be considered when modeling foam flow.

Simultaneous HPLC Assay of Gliclazide and Ciprofloxacin in Plasma and its Implementation for Pharmacokinetic Study in Rats

A simple and reliable high-performance liquid chromatography method for simultaneous quantitation of gliclazide and ciprofloxacin in plasma sample has been developed and validated. This method implements protein precipitation, a simple and practical pretreatment method by the addition of acetonitrile that gives a clean supernatant. The separation was carried out in a system consisted of a C18 column with acetonitrile and KH2PO4 (0.01 M, 0.1% v/v of triethylamine, pH 2.7) as the mobile phase in a gradient elution at a total flow-rate of 1 mL/min. Gliclazide and ciprofloxacin were quantitated using an ultraviolet detector set at wavelengths of 229 and 277 nm, respectively, which ensures optimal sensitivity for both compounds. This method possesses an excellent linearity at concentration ranges of 0.5–50 mg/L for gliclazide and 0.1–10 mg/L for ciprofloxacin. High within- and between-run accuracy for both gliclazide (% error of −8.00 to 0.45%) and ciprofloxacin (% error of −10.00 to 7.63%) were demonstrated. The intra- and inter-day precision (expressed as %CV) was <8 and 12% for gliclazide and ciprofloxacin, respectively. Both analytes were stable during storage and sample processing. The method reported in this study can be implemented for pharmacokinetic interaction study in rats.

Groundwaters of the "Valjevo karst" area (Western Serbia)

"Valjevo karst" is an area of about 780 km2 in a broader sense, while the uncovered karstified limestone makes about 330 km2. It is a part of the Inner Dinarides (Western Serbia). In the litho-stratigraphic view, the karstified limestones of Middle-Upper Triassic dominate, in which karst aquifers are formed. Analysis and systematization of the available data of hydrogeological and other relevant research is carried out. A branched network of groundwater traces between swallow holes and discharge points is presented as well as main features of sixteen karst springs (or scattered discharge zones) and nine (group of) wells, divided into five sectors. Average karst aquifer discharge of the whole area is calculated on 5.18 m3/s. Total minimum flow rate of the analysed karst springs and discharge zones is estimated at 1.2 m3/s, while the total flow rate of the analysed wells is estimated at about 0.3 m3/s, which makes about 1.5 m3/s of total (minimum) discharge. All analysed waters are low-mineralized (<1 g/l), while temperatures range from 9-35?C. Use of the waters is multipurpose: municipal and local water supply, commercial bottling, recreational pools etc.