Prediction of viscosity and surface tension of North Sea petroleum fluids by using the average molecular weight

Roenningsen, Hans Petter

doi:10.1021/ef00041a001

Cited by 21 publications

(17 citation statements)

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“…Because ions influence water structure and its behavior, surface tension can be empirically related to other bulk properties such as viscosity (η). Although an exact theoretical expression valid for any aqueous solution is not known, generally log σ ∝ 1/η. − This expression has been shown to capture the influence of the hydration (solvation) shells on both properties . The drag on the hydration shell has a larger influence on viscosity than interionic (electrostatic) forces while, for entropic reasons, solvation of an ion in the bulk phase has a larger effect on surface tension than ionic dispersion forces …”

Section: Modelmentioning

confidence: 99%

Surface Tensions of Inorganic Multicomponent Aqueous Electrolyte Solutions and Melts

2010

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A semiempirical model is presented that predicts surface tensions (σ) of aqueous electrolyte solutions and their mixtures, for concentrations ranging from infinitely dilute solution to molten salt. The model requires, at most, only two temperature-dependent terms to represent surface tensions of either pure aqueous solutions, or aqueous or molten mixtures, over the entire composition range. A relationship was found for the coefficients of the equation σ = c(1) + c(2)T (where T (K) is temperature) for molten salts in terms of ion valency and radius, melting temperature, and salt molar volume. Hypothetical liquid surface tensions can thus be estimated for electrolytes for which there are no data, or which do not exist in molten form. Surface tensions of molten (single) salts, when extrapolated to normal temperatures, were found to be consistent with data for aqueous solutions. This allowed surface tensions of very concentrated, supersaturated, aqueous solutions to be estimated. The model has been applied to the following single electrolytes over the entire concentration range, using data for aqueous solutions over the temperature range 233-523 K, and extrapolated surface tensions of molten salts and pure liquid electrolytes: HCl, HNO(3), H(2)SO(4), NaCl, NaNO(3), Na(2)SO(4), NaHSO(4), Na(2)CO(3), NaHCO(3), NaOH, NH(4)Cl, NH(4)NO(3), (NH(4))(2)SO(4), NH(4)HCO(3), NH(4)OH, KCl, KNO(3), K(2)SO(4), K(2)CO(3), KHCO(3), KOH, CaCl(2), Ca(NO(3))(2), MgCl(2), Mg(NO(3))(2), and MgSO(4). The average absolute percentage error between calculated and experimental surface tensions is 0.80% (for 2389 data points). The model extrapolates smoothly to temperatures as low as 150 K. Also, the model successfully predicts surface tensions of ternary aqueous mixtures; the effect of salt-salt interactions in these calculations was explored.

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Section: Modelmentioning

confidence: 99%

Surface Tensions of Inorganic Multicomponent Aqueous Electrolyte Solutions and Melts

2010

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“…At sufficiently high temperatures, typically above 40 °C, most crude oils, despite their enormous compositional complexity, behave like simple Newtonian liquids with a unique viscosity at any given temperature. The Newtonian viscosity can be predicted quite accurately using, for example, corresponding states models ,, or correlations in measurable physical properties such as density. , The temperature dependence is normally well described by an Arrhenius type of equation including a flow activation energy term, meaning that there is linear relationship between the logarithm of the viscosity and the inverse temperature.…”

Section: Introductionmentioning

confidence: 99%

Effect of Precipitated Wax on ViscosityA Model for Predicting Non-Newtonian Viscosity of Crude Oils

1999

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Viscosities of 18 North Sea oils (API gravity 23.8 to 47.6) have been measured at temperatures between 40 and 0 °C and shear rates ranging from 30 to 500 s-1. Precipitated wax has a pronounced effect on the viscosity and rheological behavior of these oils. At low temperatures where wax precipitation is most extensive, the oils typically behave like pseudoplastic or viscoplastic fluids. A shear-rate-dependent viscosity model is presented. It is based on a correspondence between viscosity and volume fraction of precipitated wax and further uses the Casson rheological fluid model. It contains a Newtonian and two shear-rate-dependent terms. The Newtonian term is similar to the type of viscosity models used for oil/water emulsions. The model correlates 713 measured viscosity data points with an average absolute deviation of 48%. The model has been tested on three oils not included in the data basis. The non-Newtonian viscosities of these oils (176 data points) were predicted with an average absolute deviation of 47%.

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“…A possible explanation is that when pressure decreases, light hydrocarbon components leave liquid phase increasing the fraction of heavier components in the liquid phase. Thus, liquid phase becomes more dense and possibly exhibits a behavior closer to Non-Newtonian, in which heavy oil CSP viscosity model is not appropriate 36,37 . This interpretation is clarified due to the Credible Region provided by the Bayesian approach, which is not present in classical deterministic regressions.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity Analysis, Calibration and Uncertainty Quantification for Heavy Oil Viscosity Estimates with a Corresponding States Model

Volpatto

Oliveira²,

Bittencourt³

et al. 2020

Preprint

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The main goal of this work is to assess heavy oil viscosity estimates by a Corresponding States Principle (CSP) model using a Bayesian approach in an efficient way. To determine and select relevant parameters for model calibration, an enhanced Elementary Effects method is used to evaluate sensitivity measures of CSP tuning parameters. With the combination of sensitivity analysis and Bayesian calibration, a unified procedure to automatically tune CSP viscosity model while reducing the number of tuning parameters is devised. Moreover, the Bayesian approach provides additional information on CSP model uncertainties and credible regions inherited from experimental data. To evaluate such uncertainties in CSP viscosity model, it was used five heavy oil samples available in the literature. The viscosity curves constructed by 50th-percentile from Monte Carlo realizations for the CSP calibration show good agreement when compared with classical Least-Squares regression (deterministic), demonstrating the potential of the sensitivity assessment for both Bayesian and deterministic approaches. However, when Bayesian calibration is used, limitations of CSP viscosity estimates are detected through violation of credible regions, suggesting that heavy oil viscosity estimates for relatively low pressure conditions can be insufficiently accurate for the CSP model considered in this study

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Prediction of viscosity and surface tension of North Sea petroleum fluids by using the average molecular weight

Cited by 21 publications

References 0 publications

Surface Tensions of Inorganic Multicomponent Aqueous Electrolyte Solutions and Melts

Surface Tensions of Inorganic Multicomponent Aqueous Electrolyte Solutions and Melts

Effect of Precipitated Wax on ViscosityA Model for Predicting Non-Newtonian Viscosity of Crude Oils

Sensitivity Analysis, Calibration and Uncertainty Quantification for Heavy Oil Viscosity Estimates with a Corresponding States Model

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