Water-gas Mixture Research Articles

Исследование влияния газовой фазы на структуру турбулентного течения и трение в потоке смеси воды и газа в вертикальной трубе

Исследование влияния газовой фазы на структуру турбулентного течения и трение в потоке смеси воды и газа в вертикальной трубе

Исследование газоводной смеси в полости гильзы кластерного регулирующего органа реактора РБМК-1000

Исследование газоводной смеси в полости гильзы кластерного регулирующего органа реактора РБМК-1000

The capability of radial basis function to forecast the volume fractions of the annular three-phase flow of gas-oil-water

The problem of how to precisely measure the volume fractions of oil–gas–water mixtures in a pipeline remains as one of the main challenges in the petroleum industry. This paper reports the capability of Radial Basis Function (RBF) in forecasting the volume fractions in a gas-oil-water multiphase system. Indeed, in the present research, the volume fractions in the annular three-phase flow are measured based on a dual energy metering system including the 152Eu and 137Cs and one NaI detector, and then modeled by a RBF model. Since the summation of volume fractions are constant (equal to 100%), therefore it is enough for the RBF model to forecast only two volume fractions. In this investigation, three RBF models are employed. The first model is used to forecast the oil and water volume fractions. The next one is utilized to forecast the water and gas volume fractions, and the last one to forecast the gas and oil volume fractions. In the next stage, the numerical data obtained from MCNP-X code must be introduced to the RBF models. Then, the average errors of these three models are calculated and compared. The model which has the least error is picked up as the best predictive model. Based on the results, the best RBF model, forecasts the oil and water volume fractions with the mean relative error of less than 0.5%, which indicates that the RBF model introduced in this study ensures an effective enough mechanism to forecast the results.

Разработка и апробация автоматизированной системы управления закачкой водогазовой смеси

Разработка и апробация автоматизированной системы управления закачкой водогазовой смеси

Intelligent recognition of gas-oil-water three-phase flow regime and determination of volume fraction using radial basis function

The problem of how to accurately measure the flow rate of oil–gas–water mixtures in a pipeline remains one of the key challenges in the petroleum industry. This paper proposes a new methodology for identifying flow regimes and predicting volume fractions in gas-oil-water multiphase systems using dual energy fan-beam gamma-ray attenuation technique and artificial neural networks. The novelty of this study in comparison with previous works, is using just 4 extracted features (photo peaks of 241Am and 137Cs in 2 detectors) from the gamma ray spectrums instead of using the whole gamma ray spectrum, which reduces the undesired noises and also improves the speed of recognition in real situations. Radial basis function was used for developing the neural network model in MATLAB software in order to classify the flow patterns (annular, stratified and homogenous) and predict the value of volume fractions. The ideal and static theoretical models for flow regimes have been developed using MCNP-X code. The proposed networks could correctly recognize all the three different flow regimes and also determine volume fractions with mean absolute error of less than 5.68% according to the recognized regime.

Experimental study of the flow and heat transfer of a gas–water mixture through a packed channel

Waste heat recovery from the flue gas of gas-fired boilers was studied experimentally by measuring the flow and heat transfer of air and water through six kinds of packing with saturated humid air as the simulated flue gas. The experiments measured the effects of inlet air temperature, inlet air velocity and circulating water flow rate on the flow and heat transfer. The results show that higher inlet air temperatures and lower inlet air velocities lower the flow resistance and increase the heat transfer coefficient. The stainless steel packing had better surface wettability and larger thermal conductivity than the plastic packing, which enhanced the heat transfer between the water and the saturated moist air. When both the flow resistance reduction and the heat transfer enhancement were considered, the experimental results gave an optimal packing-specific surface area. A packed heat exchanger tower was designed for waste heat recovery from the flue gas of gas-fired boilers based on the experimental results which had better flow and heat transfer characteristics with lower pump and fan power consumption, more stable system operation and less thermal fluctuations compared with a non-packed heat transfer system with atomized water.

ChemInform Abstract: Fluid‐Mineral Equilibria and Thermodynamic Mixing Properties of Fluid Systems

AbstractReview: 44 refs.

Эффективность применения водогазовых смесей для повышения нефтеотдачи и перераспределения фильтрационных потоков

Эффективность применения водогазовых смесей для повышения нефтеотдачи и перераспределения фильтрационных потоков

The effects of quartz content on the formation of residual water in a brine–CO2–quartz system: An experimental study

Geo-sequestration of CO2 in deep saline aquifers is achieved by injecting CO2 into the aquifers and displacing brine. The residual water formed during the drainage process has a strong influence on traps of residual-gas. Moreover, in the context of CO2 geological storage, the characteristics of the brine–CO2–quartz system directly impact residual trapping capacities. We conducted experiments to investigate the influence of quartz content in the rocks on the formation of residual water and how much of this residual water remains after CO2 is injected. Three sandstone core samples were all saturated with 35 g/L NaCl brine. Supercritical CO2 was injected into the samples at aquifer temperature and pressure and the displaced water and water-gas mixtures were collected and measured. The results show that the irreducible water saturation was lower with higher quartz content in the rock core. The permeability of rock cores can only influence the drainage efficiency; it does not have a decisive impact on the irreducible water saturation. Based on drainage flow rates, the process of drainage can be divided into three stages termed: Pushing Drainage, Portable Drainage and Dissolved Drainage. This terminology differs slightly from previous time-frame characterizations. Note that we have used a capillary model to interpret the mechanisms that characterize the three stages in these experiments.

Analysis of the influence of wettability on permeability in hydrate-bearing porous media using pore network models combined with computed tomography

The permeability of hydrate-bearing porous media is one of the most important factors in predicting fluid flow behavior, fluid distribution, and gas performance during hydrate exploitation. The wettability of porous media greatly affects the relative permeability of two-phase gas-water mixtures. In this paper, we extend our previous investigation into the effects of the wettability of porous media containing hydrates on their seepage properties using pore network models combined with X-ray computed tomography (CT). The simulation results show that in a uniform wetting system, increasing the contact angle reduces the wettability of hydrate-bearing porous media, increases the relative permeability of the water phase, and decreases the relative permeability of the gas phase at a given water saturation. In addition, increasing the diameter of quartz sand particles notably enhances these changes in the gas-water phase relative permeability. In a fractional-wetting system, increasing the fractional wettability and connectivity effectively reduces the residual gas saturation. Moreover, the capillary pressure distributions are highly dependent on the fractional wettability and quartz sand size.

Moment Tensor Inversion of Seismic Events Associated with the Sinkhole at Napoleonville Salt Dome, Louisiana

Abstract The formation of a large sinkhole at the Napoleonville salt dome, Assumption Parish, Louisiana, in August 2012 was accompanied by a rich sequence of complex seismic events. We implemented a grid‐search approach for automatic detection, location, and full moment tensor (MT) inversion of these events using 0.1–0.2 Hz displacement waveforms and 1D velocity models for the salt dome and the surrounding sedimentary strata. We were able to detect 62 events, with a 70% variance reduction (VR) detection threshold, during the one‐day period (19:00 hours, 1 August to 19:00 hours, 2 August, 2012) just before the discovery of the sinkhole. The source mechanisms of these events show large isotropic volume‐increase components (61%–82%), with magnitudes varying from M w 1.3 to 1.6 and good waveform fits (71%–86% VR). Locations are well constrained to an approximate depth of 470 m at the western edge of the salt dome, close to the sinkhole. For one representative event, the large volume‐increase component in the full MT solution is statistically significant over the deviatoric MT solution and stable with respect to: (1) the velocity models and stations used in the inversion, and (2) the uncertainties in the hypocenter and the MT solution itself. The network sensitivity solution computed for this event using both waveforms and P ‐wave first motion polarities provides greater confidence in the dominantly explosive source mechanism, which can be attributed to high‐pressure flow of natural gas or gas–water mixture through the disturbed rock zone below the sinkhole or pre‐existing zones of weaknesses in the source region. Online Material: Figures showing Q sensitivity, spatial distribution of moment tensor solutions, waveform fits from inversion and 1D models, and tables of the velocity model and event catalog.

Density and phase equilibrium for ice and structure I hydrates using the Gibbs–Helmholtz constrained equation of state

A new, rigorous framework centered around the multi-scale GHC equation of state is presented for predicting bulk density and phase equilibrium for light gas–water mixtures at conditions where hexagonal ice and structure I hydrate phases can exist. The novel aspects of this new framework include (1) the use of internal energies of departure for ice and empty hydrate respectively to determine densities, (2) contributions to the standard state fugacity of water in ice and empty hydrate from lattice structure, (3) computation of these structural contributions to standard state fugacity from compressibility factors and EOS parameters alone, and (4) the direct calculation of gas occupancy from phase equilibrium. Numerical results for densities and equilibrium for systems involving ice and/or gas hydrates predicted by this GHC-based framework are compared to predictions of other equations of state, density correlations, and experimental data where available. Results show that this new GHC-based EOS framework accurately predicts the densities of hexagonal water ice and structure I gas hydrates as well as phase equilibrium for methane–water and CO2–water mixtures.

The Design and Research on a Gas-Water Mix-Type Marine Fire Hydrant Based on Fluid Mechanics

The existing fire-extinguishing plants have a lot of problems. For example, the amount of extinguishant is very large, mix is uneven, extinguishant is easy to splash, harmful to the human, the system structure is complex, spray nozzle is demanding and so on. And the open literature sources on the marine fire hydrant are very few. Besides because of the difficulty of numerical simulation of two-phase flow, the research on numerical simulation of the marine fire hydrant is hardly any. In this thesis, a new-style marine fire hydrant is designed to be small volume, easy to use and low pressure lost. It blends the gas to water through its special structure. It regards the gas-water mixture as the extinguishant. In this way, the water flow can be soften, and reduce the splash. The extinguishant can overlay the burnable body uniformly. At last, reach the better extinguishant under the dual effect of the oxygen exclusion and cooling.

Fluid-mineral equilibria and thermodynamic mixing properties of fluid systems

The paper presents a review of an experimental method to quantitatively constrain thermodynamic mixing properties of fluid systems at high temperature T and pressure P. The method is based on bracketing equilibrium parameters of simple fluid-mineral reactions. Experimental data obtained with this technique for the H2O-CO2, H2O-N2, and H2O-H2 binary systems were utilized to calculate mixing parameters corresponding to the simplified van Laar model W12VL, according to which the equation for the integral excess Gibbs free energy of a binary mixture Gex is Gex =X1X2W12VL/(X1V10 + X2V20), where Xi is the mole fractions of the components, and Vi0 are pure species molar volumes at given P and T (in cm3). The W12VL for the three mixtures correspond to 202, 219, and 331 kJ cm3/mol. The empirical correlation \(W_{H_2 O - X}^{VL}\) (kJ cm3/mol) = 887.012 QX − 16.674, where Q = Pc (critical pressure, bar)/Tc (critical temperature, K) for gas X (where X = CH4, CO, H2S, O2, Ar, and NH3) is used to evaluate the van Laar parameters for a number of petrologically important water-gas mixtures. The H2O-H2 system is characterized by the greatest positive deviation from the ideal mixing and can thus decompose into two immiscible fluid phases under the P-T parameters typical of deep lithospheric zones. The exsolution of the H2O-CO2 and H2O-N2 systems is expected to occur only under high pressure and low temperature. This combination of parameters may be expected only in the environments of cold subduction. Salts (highly soluble simple salts and/or silicates) should significantly expand the exsolution regions in petrologically important fluids.

Reduced fuel in charge of iron ore agglomeration by supplying a sintered layer and the gas-water mixture

The possibility of improving the parameters of the sintering process of iron ore sa charge by the joint submission of the driver and hydrocarbons.

Oil recovery in the presence of microbubbles in the filtration flow

This paper presents mathematical models for oil-gas flow taking into account the various processes due to the formation of gas micronuclei (microbubbles) in oil: slip of oil relative to the walls of the pore channels (gas lubrication), changes in oil viscosity, and motion of microbubles with respect to oil. We consider examples of oil flow in the near-wellbore zone for the case where a reduction in pressure to the saturation pressure leads to the formation of gas microbubbles and micronuclei and examples of the action of a water-gas mixture in the case where oil foams in the contact area with the injected gas, i.e., a finely dispersed mixture of oil and microbubbles is formed. The behavior of indicator curves for an oil well with the formation of microbubbles is simulated, and the effect of microbubbles on the oil recovery factor in a water-alternating-gas injection process is studied.

Synthesis of Effective Kinetic Inhibitors for Natural Gas Hydrates

Six novel polymer-based kinetic hydrate inhibitors (KHIs) were synthesized and characterized. Their performance in inhibiting both tetrahydrofuran (THF) hydrate and the synthetic gas hydrate formation was examined using two different instruments: a ball-stop apparatus and a high-pressure automatic lag time apparatus (HP-ALTA). Performance was benchmarked against two commercially available KHIs, Gaffix VC-713 and Luvicap EG, under the same working conditions. The test results from the ball-stop rig demonstrated that the new KHIs were as effective as Gaffix VC-713 and Luvicap EG in preventing the formation of THF hydrates in 3.5 wt % NaCl solutions. For the synthetic gases, most new polymers outperformed the reference KHIs at a concentration of 0.05 wt %. Polymers containing a pendant THF functional group in the side chains showed a substantial 12–16 °C decrease in the hydrate formation temperature of the gas water mixtures relative to those containing the same amount of Gaffix VC-713 or Luvicap EG. The trend of the inhibition performance of the polymers was different in THF from that measured for gas mixtures. Small amounts of ethanol added to the hydrate formation mixtures were also shown to have an effect. Investigation of the inhibition mechanism associated with these new polymers is under way.

Vitrification and crystallization of low-temperature amorphous condensates of water and methane—water mixture

Low-temperature condensates of water and water-methane mixture are studied in the temperature range of 65–200 K. Amorphous samples are obtained by molecular beam deposition under vacuum conditions on the substrate cooled with liquid nitrogen. The vitrification and crystallization temperatures are determined from the changes in the dielectric properties of the condensates upon heating. The kinetics of crystallization of amorphous water layers is studied by differential thermal analysis. The temperature conditions for the growth of thick methane crystalline hydrate layers during the low-temperature condensation of molecular water-gas mixture beams are found.

Glass transition and crystallization of low-temperature amorphous condensates of the water-propane mixture

Interest in gas hydrates stems from the existence of vast reserves of hydrocarbons on the earth in the form of gas hydrates, prospects for using them as a fuel source, and the possibility of storage and transporta� tion of gas in the gas hydrate state. The known meth� ods of production of gas hydrates are based on rela� tively small deviations from the equilibrium condi� tions of gas dissolution. They require the use of high pressures in laboratory or manufacturing equipment. For example, the pressure corresponding to the for� mation conditions of methane hydrate at temperatures near 0°С amounts to tens of bars. In addition, forma� tion of the crystal hydrate requires dispersion of water, which is afforded by longterm and vigorous stirring of the water-gas mixture. In this work, we have proposed another approach implying that hydrates are formed under conditions far from thermodynamic equilibrium. The approach is based on lowtemperature molecularbeam deposi� tion in a vacuum onto a surface cooled by liquid nitro� gen. During this process, amorphous (glassy) layers of the water-gas mixture are initially formed, which are stabilized by high viscosity. Heating of the amorphous layers is accompanied by avalanchetype nucleation and growth of gas hydrate crystallization sites. This method requires neither high pressures nor stirring of the water-gas system. Its advantage is that it is univer� sal and can be used for producing various gas hydrates. This work deals with studying the glass transition and crystallization of amorphous condensates of the binary water-propane system obtained by lowtem� perature condensation to determine the conditions of crystal hydrate formation. Amorphous solid (glassy) layers of lowmolecular� weight substances can be obtained by molecularbeam deposition onto a cooled surface. At low temperatures, the amorphous state of these substances is stabilized by the high viscosity. Molecularbeam deposition onto a copper substrate cooled by liquid nitrogen affords amorphous layers of water and simple molecular com� pounds (1), as well as of aqueous solutions of organic liquids (2). Cooling rates under these conditions are as high as 10 5 -10 7 K/s. On heating, the condensates undergo glass transition (softening) and subsequent spontaneous crystallization. In the course of the latter, a decisive role for phase transformation is played by homogeneous nucleation. The crystallization of amorphous water-gas condensates can result in the formation of gas hydrates (3-5). Hydrate formation is facilitated by the low chemical affinity of the hydrate� forming substance, as well as by the size and shape of its molecules corresponding to the geometry of cavi� ties in the arising clathrate framework. Among such substances, there are light hydrocarbons of the meth� ane series. Experiments with lowtemperature con� densates of the water-methane mixture showed the possibility of producing massive samples of crystal hydrates with high gas content capable of sustained burning (5).

Mechanistic Analysis of Gas Enrichment in Gas–Water Mixtures near Extended Surfaces

We investigate gas enrichment near extended surfaces for gas–water mixtures using molecular dynamics simulations. We develop a detailed understanding of the various interactions that are responsible for gas enrichment by considering different gas–water mixtures and surfaces. We identify the significance of the solvent–induced potential on gas and show that both the solvent–induced potential and the gas–wall potential play an important role in gas enrichment. We perform a detailed thermodynamic analysis and discuss the significance of the entropic and enthalpic components of the solvent–induced potential for gas enrichment.