Kwong Equation Research Articles

Dynamical and rheological analysis of gas condensate reservoir characteristics and multiphase flow behavior of a well

This manuscript proposes dynamical and rheological analysis of gas condensate reservoir characteristics and multiphase flow behavior of a well located at the lower Indus basin gas condensate reservoir in Sindh, Pakistan. The main objective is to analyze the compositional variation impacts on the liquid dropout, flow behavior and well productivity. For the sake of data analysis, constant composition expansion and constant volume depletion capabilities have been tested via pressure, volume and temperature cell under measurement of dew point and liquid dropout flow. By invoking CMG: Win prop simulator on the basis of equation of state namely Peng Robenson and Soave Redlish Kwong equations, phase diagram and well stream physical parameters have been analyzed. Our result suggested crucial significance for the behavior of flow and well productivity that liquid generation changes with the physical properties of flowing stream namely vapor viscosity, compressibility factor and vapor density due to pressure depletion showing decreasing trend. Mole percent of lighter components C1 mole percent increases from 54.567 to 62.153. While mole percent of heavier components C18+ decreases from 3.453 to 1.513 with 45% liquid dropout. In brevity, maximum well productivity has been observed in composition-1 which is 5.005 MMscf/day at pressure of 3131 psig.

A-priori framework of viscosity and ionic conductivity estimation of ionogel

A-priori framework has been developed to estimate the viscosity and ionic conductivity of ionogel. Six imidazolium-class of ionic liquids (ILs) form ionogels with tetraethyl orthosilicate (TEOS) matrix. Group contribution parameters of TEOS are estimated with the fitting of the density dataset in the predictive Soave−Redlich−Kwong equation of state with the NSM1 alpha function model. Later the parameters are used to estimate the critical property of ILs and TEOS. These facilitate the formulation of the predictive framework of viscosity estimation through the geometric similitude concept with the Valderrama-Patel-Teja cubic equation of state. Later the viscosity of ionogels is estimated through a mixture form of geometric similitude framework as well as the Arrhenius model. Additionally, the estimated viscosities from both frameworks are used to estimate the ionic conductivities of ionogels. The compositional and temperature variance of ionic conductivity reveals the superior ionic conductivity of tetrafluoroborate-based ionogels than the bis(trifluoromethanesulfonyl) imide-based counterparts. Both models estimate the decrease in viscosity as well as incremental trends in ionic conductivity with temperature. However, the concentration of IL rather plays a different trend in the estimation model as well as the class of IL. Such a priori framework shall lead to the design of the ionogels focusing on the physicochemical properties.

Experimental study and thermodynamic modeling of CO2+CH4 gas mixture hydrate phase equilibria for gas separation efficiency

Gas separation is a critical application of gas hydrates, and accurately predicting separation performance is crucial. In this study, we used thermodynamic calculations to predict the equilibrium phase of gas hydrates for various mole fractions of CO2 + CH4 gas mixtures. We also determined the mole fraction of each gas component trapped within the hydrate clathrate. To predict the equilibrium points, we used the Soave–Redlich–Kwong（(SRK) equation of state for the gas phase, the nonrandom two-liquid (NRTL)model for the liquid phase, and the Chen–Guo model for the hydrate phase. We modified the hydrate fugacity formula and introduced a new function to improve the accuracy of the Chen–Guo model. By incorporating experimental equilibrium results from our study and another study, we developed a correlation based on gas mixture composition and temperature, resulting in highly accurate predictions. The use of this new correlation for hydrate fugacity calculation significantly improved precision, as evidenced by an average absolute deviation percent of calculated pressures (AADP) of 1.34% for pure CO2 and 1.25% for CH4. When considering the 27 data points of different CO2 + CH4 mixtures, the AADP% was 1.98%.To implement the model to predict equilibrium phases, we used the Chen–Guo framework to determine the mole fraction of each gas component in the hydrate mixture. Interestingly, we discovered a linear correlation between the CO2 mole fraction in the hydrate and equilibrium pressure, with a slope of approximately 0.001 and a y-intercept of less than one, for all gas compositions. Therefore, we can conclude that low thermodynamic conditions (temperature and pressure) result in a high CO2 mole fraction in the hydrate phase and great separation efficiency.

Analysis of the Effect of Sampling Probe Geometry on Measurement Accuracy in Supersonic Gas Flow

The accuracy of sampling of gas components has a significant impact on the measurement of various performance parameters in the combustion chamber of an aero-engine. In order to investigate the effect of the probe geometry of a six-point gas sampling probe on sampling accuracy in supersonic gas flow, a three-dimensional probe gas flow characteristic solution model is established through numerical simulation methods of components of transport and fluid–solid coupling. Probes with three angles of 28°, 30°, and 32° and an optimized conical probe are constructed. The sampling accuracy of the probes with different geometries is compared and evaluated by the deviation of the component volume fraction before and after sampling and the resulting combustion efficiency error. This paper presents a set of calculation methods for solving the relative deviation of volume fraction by an iterative method based on the ideal gas law and the Redlich–Kwong equation (R-K equation). The method is designed to solve the exact component volume fraction problem in the simulation calculation. The study results demonstrate that the 28° and optimized conical probes improve sampling accuracy more effectively than the original 30° structure. The deviation of the volume fractions of the two structures is less than 1.7%, and the combustion efficiency error is less than 0.09%. The developed iterative calculation method can significantly reduce the theoretical calculation error to less than 0.06%. The experimental data of the test bench are in good agreement with the simulation results, thereby demonstrating the reliability and accuracy of the sampling probe following structural optimization.

Equilibrium Study of Carbon Dioxide Reforming of Methane to Syngas

Fugacity coefficients for the components in the gas mixture are determined using the Soave–Redlich–Kwong (SRK) equation of state. The Gibbs free energy minimization method is employed to determine the equilibrium composition of the components for CO2 reforming of CH4 to syngas. To utilize CO2 efficiently and avoid carbon deposition, CO2 composition in the initial feed should not be greater than 1 (nCH4,0 = 1), and the reaction is preferably operated at atmospheric pressure. Setting nCH4,0:nCO2,0 to 1:1, and increasing nO2,0 in the feed from 0 to 1.0 to adjust the initial composition, results in a decrease in the syngas equilibrium yield, and a increase in both nCO2,e and nH2O,e. The temperature required for complete carbon deposition removal decreased. Considering the effective utilization of CO2 at nCH4,0:nCO2,0 1:1, it is recommended to set nO2,0 in the feed to less than 0.5.

WITHDRAWN: Comparative Analysis of Asphaltene Deposition Methods : Stability indices, Stability plots, and Equation of state

Asphaltene deposition is one of the major problems that hinder hydrocarbon production. It can occur anywhere between the reservoir and the surface. Therefore, it is imperative that there be a procedure for minimizing the deposition of asphaltene in the production flow lines. There are several screening criteria that can be considered to determine the asphaltene deposition. This research will conduct a comprehensive study on different methodologies to determine the stability of asphaltene: the first category is the stability criteria using indices such as: the colloidal instability index (CII), the colloidal stability index (CSI), the stability index (SI), and the asphaltene stability predicting model (ANJIS). These four methods are used to predict the stability of asphaltene using SARA analysis. The fifth one is called modified CII which uses the compositions analysis of reservoir fluids, instead of SARA analysis, to determine the stability of asphaltene. The second method uses SARA Analysis to predict the stability via plots such as: Stankiewics plot (SP), De Boer plot, Sepulveda stability criterion (SCP). The third method is using compositional analysis of reservoir fluids and the equation of state model to predict the asphaltene onset pressure (AOP). In the last method Soave Redlich Kwong (SRK) equation of state model was used to predict asphaltene precipitations.In this work, a dataset of 166 was created which includes reservoir information, depth, compositional analysis, and SARA analysis. These data are used to study the potential of asphaltene deposition at the reservoir level. It was found that the stability criteria using indices and plots shows discrepancy in the results. The only two methods that show all the datasets are stable are the modified CII and the EOS model. As far as predicting asphaltene stability is concerned, the EOS method, based on compositional analysis and the thermodynamic model, appears to be the most reliable and trustworthy method. The other methods presented are observational rather than thermodynamic. Using these criteria is intended as a quick and fast estimate of the stability potential of asphaltene, not for planning or management of asphaltene deposition issues.

Approximate Riemann Solvers for the Soave – Redlich – Kwong Equation of State

Approximate Riemann Solvers for the Soave – Redlich – Kwong Equation of State

Geometric similitude concept and Redlich–Kwong equation of state to predict thermal conductivity of choline chloride class of deep eutectic solvent

Geometric similitude concept and Redlich–Kwong equation of state to predict thermal conductivity of choline chloride class of deep eutectic solvent

Interpretation of covolume in an extension of the Redlich–Kwong equation of state for real gases

Interpretation of covolume in an extension of the Redlich–Kwong equation of state for real gases

Investigation of the Solubility of Methane and Ethane in Hybrid Sweetening Solutions of 2-Aminoethanol and 1-Methylpyrrolidin-2-one/Water

Hydrocarbons of natural gas are captured by the solvent in the gas-sweetening absorption process and added to losses in production. Therefore, knowledge of hydrocarbon solubilities in solvents is required to assess and overcome these losses. In this study, the solubility of the main components of natural gas, methane and ethane, in n-methyl-2-pyrrolidone and monoethanolamine-based solvents was determined at the temperature of 313.15 K and pressures up to 2.366 MPa. Mass fractions of 0.10, 0.20, and 0.30 amine in the solutions were used in measurements that were performed using a static-synthetic method. The experimental data were modeled using the Soave–Redlich–Kwong Equation of State. Experimental results showed that the replacement of the aqueous part of conventional monoethanolamine solvents with n-methyl-2-pyrrolidone increased the solubility of desirable components of natural gas which is a negative side effect. The addition of monoethanolamine to n-methyl-2-pyrrolidone outperformed the Purisol solvent in terms of carbon dioxide absorption and decreased hydrocarbon solubility.

Effects of effluent pressure on the thermal cracking of crude oil: insights from thermal simulation experiments and phase analysis

This study discusses the anhydrous glass tube isothermal pyrolysis simulation for a crude oil, in order to explore the effects of effluent pressure on crude oil cracking. The results of gas chromatograph indicate that effluent pressure promotes the cracking of crude oil, increasing yields of C1–C5 saturates but inhibiting the generation of olefins. According to the calibration result of Soave–Redlich–Kwong equation of state, fluid phase transitions occur at very high effluent pressures, resulting in constant effluent pressure with no further increase in cracking efficiency and with invariant yields of pyrolysates. This study suggests that fluid phase transitions should be considered in petroleum exploration, which can help us to precisely determine the type of petroleum resources.

Diffusion Coefficient and Absorption of Carbonyl Sulfide in 1-Hexyl-3-methylimidazolium Bis (Trifluoromethyl) Sulfonylimide ([hmim][Tf2N

The solubility of carbonyl sulfide (COS) and also the diffusion coefficients of COS, carbon dioxide, and hydrogen sulfide were experimentally investigated in 1-hexyl-3-methylimidazolium bis(trifluoromethyl) sulfonylimide ([hmim][Tf2N]). The solubility was measured using a static apparatus, and the acid gas diffusivity was obtained by monitoring pressure drop with low initial pressure via the so-called semi-infinite volume method. All experimental absorption trials were carried out in the range of low and medium pressures and temperatures from (313.15 to 353.15) K. Furthermore, all diffusion coefficient experiments were determined at a temperature from (313.15 to 333.15) K and low pressure to some extent to be acceptable in the semi-infinite volume approach. The experimental results were correlated using the Shiflett and Yokozeki versions of the Redlich–Kwong equation of state. In addition, Henry’s law constants and the thermodynamic properties of dissolution at infinite dilution were calculated and discussed.

Examination of Condensation Liquid Formation in Istanbul Natural Gas Distribution Network

In this study, the formation of natural gas liquid in gas distribution lines, particularly at regional stations, service boxes, customer installations, and gas meters, was investigated. The study aims to address the problems associated with natural gas liquid formation, such as interruption of supply and decreased efficiency of combustion devices. The indirect measurement of the hydrocarbon dew point was analyzed using C6+ chromatograph data, and the model based on directly measured C6+ data were converted into C6/C7/C8 data by four different methods. As distinct from studies in the literature, this study experimentally determines the distribution of heavy hydrocarbons from C9 to C19 based on indirect methods for acquiring C8+ data and direct measurement of C6+ data. The hydrocarbon dew point temperature was calculated using the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state. The results of the analysis performed on two city gate stations showed that the critical temperatures were 4.21 °C at a pressure of 10.81 bar and 8.27 °C at a pressure of 11.25 bar, respectively. These values were obtained from a model designed to determine the dew point temperature in the area where natural gas liquid formation was most prevalent. The experimental analysis and indirect measurements indicated the occurrence of a two-phase gas–liquid formation.

Validation of Soave–Redlich–Kwong equation of state coupled with a classical mixing rule for sound speed of non-ideal gas mixture of oxygen-hydrogen as liquid rocket propellants

Numerical simulations of inlet jets flow of propellants in the main combustion chamber equipped in a liquid rocket engine have been conducted by compressible CFD technics employing a van der Waals-type equation of state (EOS) and chemical reaction models. Various simulations have been already conducted both for combustion and non-combustion state in the chamber; however, the accuracy of EOS for the mixture of propellant employing a classical mixing rule (CMR), particularly for the sound speed, has not been understood well. Therefore, we have validated the applicability of Soave–Redlich–Kwong (SRK) EOS as one of the van der Waals-type EOSs coupled with the CMR for the sound speed using molecular dynamics (MD) simulations against an imaginary model of oxygen-hydrogen mixture system. We found that SRK EOS coupled with a well-employed CMR can reproduce the sound speed in the MD simulations within a relative error of several percent and that the CMR hardly increases the deviation of the SRK EOS in the single component. The present results suggest that the SRK EOS with the CMR cannot be the main factor to cause critical errors in the CFD based on RANS, which will give reliability to current CFD simulations for internal flows in a combustion chamber of a liquid rocket engine.

Solubility and thermodynamic modeling of sildenafil citrate in supercritical carbon dioxide

Determining the solubility of drugs in supercritical carbon dioxide (SC-CO2) is crucial to select an adequate SC-CO2 assisted technique (e.g., supercritical anti-solvent, rapid expansion of supercritical solution, etc.) to produce micro or nano sized drug particles. In this study, the solubility of sildenafil citrate (SLC) in SC-CO2 using a static method was measured and modeled for the first time. For this purpose, experiments to measure the solubility of SLC in SC-CO2 were carried out at different temperature (308 to 338 K) and pressure values (12 to 30 MPa). The solubility expressed as molar fraction and g/L of SLC in SC-CO2 was quantified in the range of 2.40 × 10−7 to 6.48 × 10−6 and 0.001 to 0.079 (g/L), respectively. Various models were used to correlate the measured solubility data, including the Soave Redlich Kwong (AARD = 14.33) and PC-SAFT theory (AARD =10.26) equations of state (EoS), the Modified Wilson's model (AARD=7.80), and Chrastil (AARD = 7.90), Bartle et al. (AARD = 8.75), Méndez-Santiago-Teja (AARD = 6.50), and Kumar-Johnston (AARD =5.30) as the density-based semi-empirical models. Finally, the approximate values of total (ΔHtotal), vaporization (ΔHvap), and solvation (ΔHsol) enthalpies were computed.

Применение моделей реального газа к задаче обтекания тела высокоскоростным потоком

The paper presents results of computational simulation of the high-speed airflow around an axisymmetric body using various models that include ideal gas described by the Mendeleev—Clapeyron equation, real gas described by the Redlich—Kwong equation and user model approximating the empirical data. The user model is characterized by its own program code for the two-parameter approximation of the air thermophysical properties and taking into account in this context changes accompanying dissociation phenomena occurring at high temperatures without simulating physical and chemical transformations in the multicomponent gas mixture. The purpose of this study is to evaluate differences in the gas-dynamic flow pattern, shock-wave structure and thermal loading of the streamlined body depending on selection of the medium model. The results obtained make it possible to conclude on the need to introduce the real gas user models to reduce the error of computational simulation and ensure correct estimation of the heat flows.

Theoretical determination of vapour–liquid equilibrium pressure and vaporisation enthalpy of rubidium in the temperature range of 700 K–2017 K based on a modified Redlich–Kwong equation of state

ABSTRACT Based on a four-parameter modified Redlich–Kwong equation of state (m-RK EoS), the vapour–liquid equilibrium pressure of rubidium over a temperature range of 700 K–2017 K is determined using Maxwell’s equal area construction. The obtained values of vapour pressure of rubidium agree with the literature values. In this work, the vapour pressure precision is taken as 10−5 Pa which is, in fact tuneable, depending upon the accuracy requirement. Correlations for the temperature-dependence of vapour pressure of rubidium are obtained through least square analysis based on the obtained vapour pressure data. Also, the curvature of the obtained reduced vapour pressure curve for rubidium is found to have a maximum at 1208.80 K. Moreover, the vaporisation enthalpy of rubidium is determined from the proposed vapour pressure correlation and has reasonable accuracy in the temperature of 700 K–1400 K.

Comparison of pure component thermodynamic properties from CHEMCAD with direct calculation using the Soave–Redlich–Kwong equation of state

Gas-phase thermodynamic properties are routinely calculated with equations of state in process design software such as CHEMCAD [1], and users should be able to verify the calculations. In a previous study, we reproduced the enthalpy, entropy, compressibility factors, and fugacity coefficients obtained from CHEMCAD using the Lee–Kesler method [2, 3], and later extended this study to include the Peng–Robinson equation of state [4, 5]. An interesting feature of the earlier work is that compressibility and fugacity coefficients in CHEMCAD did not match up precisely with our independent calculations. We therefore extended the study to include the Soave–Redlich–Kwong (SRK) equation of state [6, 7]. Our results show consistency for most of the 48 molecules studied, with percent error in enthalpy decreasing significantly for the SRK method to generally less than 0.002% compared to about 0.3-1% for the Lee–Kesler and Peng–Robinson methods. Unlike the previous two studies, we now see nearly perfect agreement in the compressibility and fugacity coefficient. Furthermore, we show that compressibility and fugacity coefficient remain constant in CHEMCAD even when the equation of state is changed. For enthalpy, while the results are much closer than in the previous studies, we see deviations for methane, air, carbon monoxide, carbon dioxide, nitrogen, and oxygen. Discrepancies in entropy were also observed for bromine, carbon dioxide, chlorine, hydrogen sulfide, and nitrous oxide.

Isothermal Vapor–Liquid Equilibrium for the Tetrafluoromethane (R14) + Octafluoropropane (R218) Binary Mixture at Five Temperatures from 173.150 to 213.150 K

Tetrafluoromethane (R14) and octafluoropropane (R218) are essential nonflammable refrigerants for mixed-refrigerant Joule Thomson refrigerators. In this paper, the vapor–liquid equilibrium (VLE) data were acquired for the R14 + R218 binary mixture from 173.150 to 213.150 K by a vapor-phase single-cycle method. The VLE data were regressed by the Soave–Redlich–Kwong (SRK) equation of state plus van der Waals (vdW) mixing rule model (SRK-vdW) and the Soave–Redlich–Kwong (SRK) equation of state combined with modified Huron–Vidal first-order (MHV1) mixing rule plus non-random two liquids (NRTL) activity coefficient model (SRK-MHV1-NRTL). The maximum average absolute relative deviation of pressure (AARDp) and the maximum average absolute deviation of vapor-phase mole concentration (AADy) are 2.42% and 0.0019 for the SRK-vdW model, respectively. A better correlation result was obtained by the SRK-MHV1-NRTL model, and the maximum AARDp and AADy are 1.04% and 0.0019, respectively. Based on the experimental and calculated results, a strong non-azeotropic behavior was found.

Effect of electrolyte solubility and column inclination on the performance of monoethylene glycol regeneration process

AbstractIn this study, the solubilities of potassium‐chloride (KCl) in aqueous monoethylene glycol (MEG) solution and the vapour pressure of aqueous MEG solution containing KCl were investigated. A thermodynamic model was modified based on the data obtained to predict the solubilities of KCl, which was then applied to optimize the MEG regeneration process that is widely used in offshore gas fields. The solubility of KCl in the aqueous MEG solution decreased with an increase in MEG concentration and a decrease in temperature. The presence of KCl in aqueous MEG solution decreased the vapour pressure, thus increasing the boiling temperature at the corresponding pressure. A thermodynamic model based on the electrolyte non‐random two‐liquid (NRTL) coupled with the Redlich–Kwong (RK) equation of state was employed by modifying the binary interaction parameters using the experimental data. The modified model predicted the solubilities of KCl and the vapour pressure of aqueous MEG solutions, which were in good agreement with the experimental data. Moreover, the distillation column in pilot‐scale MEG regeneration was inclined to simulate the movement of the offshore platform, showing decreasing MEG concentration, possibly due to the distribution issues inside the column.