Viscosity, density, interfacial tension and compositional data for near critical mixtures of methane + butane and methane + decane systems at 310.95 K

doi:10.1016/j.fluid.2005.03.032

Fluid Phase Equilibria

Volume 233, Issue 2, 30 June 2005, Pages 144-150

https://doi.org/10.1016/j.fluid.2005.03.032 Get rights and content

Abstract

Single- and two-phase binary mixtures of near critical methane + butane and methane + decane systems have been investigated at 310.95 K. A capillary tube viscometer was used to measure the viscosity and a high-pressure densitometer was employed for density measurements. The mixture was prepared gravimetrically and a direct sampling system was used to measure the composition of equilibrium phases in the two-phase region by gas chromatography. The meniscus height technique was used to generate the interfacial tension data.

Introduction

Thermodynamic and rheological properties of hydrocarbon mixtures are required for hydrocarbon reservoirs exploitation, process design and management in the oil industry. While reliable data on pure hydrocarbon compounds are used to develop theoretical models, measured data on mixtures are needed to extend these models to more complex and challenging systems. Researchers, worldwide, have studied and reported the fluid phase and flow properties of a number of binary and mulitcomponent mixtures of hydrocarbons over wide ranges of temperature, pressure and composition. Despite this pool of information, reliable data on physical and rheological properties of hydrocarbon mixtures at the near critical point is still scarce.

In this study the viscosity, density, interfacial tension (IFT) and equilibrium phase composition of a near critical methane + butane binary mixture have been measured at 310.95 K. Viscosity data has also been generated above and below the saturation pressure of a near critical methane + decane mixture at 310.95 K. An oscillating tube densitometer and a capillary tube viscometer have been used to make the measurements.

Section snippets

Apparatus

A vapour–liquid equilibrium (VLE) facility was employed to conduct the measurements in this study. The VLE facility can be used for studying the phase and volumetric behaviour of pure, multicomponent model mixtures and real reservoir fluids. It is capable of measuring the dew point, bubble point, phase volumes, high-pressure phase composition, viscosity, density and interfacial tension (by two methods, meniscus height and pendant drop). Measurements can be made from ambient conditions to a

Composition measurements

The direct sampling system was used to measure the equilibrium phase compositions at the test pressure. The technique is based on pinching a small amount of a high-pressure fluid in a narrow tube by a solvent at the test conditions. The flow of the solvent directs the slim slug of the sample into a high-pressure valve, where approximately 0.06 μl of the sample is directly injected into a gas chromatograph. Dichloromethane is usually used as the solvent. A detailed description on compositional

Methane + butane

The binary mixture of methane + butane was prepared gravimetrically in a solvent clean and evacuated titanium vessel. Methane (C₁, 99.995% Air Products) and normal butane (n-C₄, 99.5%, BOC) were individually weighed (Sartorius I 8100 P top pan balance, accuracy ±0.02 g) and added to the vessel. The prepared methane + butane binary mixture contained 73.6 mole% methane and a dew point of 12.89 MPa was measured at 310.95 K. The sample was then stabilised at pressures below the dew point pressure and the

Conclusions

Single- and two-phase composition, density and viscosity of near critical methane + butane and methane + decane systems at 310.95 K have been measured and compared with available literature data, generally showing reasonable agreement. For the near critical methane + decane mixture, a 10% viscosity enhancement with pressure reduction was observed upon approaching the saturation pressure. Binary mixtures of methane + decane with a saturation pressure of about 2 MPa below the critical pressure of the

Acknowledgements

This research work was funded by the European Union project (EviDenT) under the Joule Programme, Contract No. JOF3-CT97-0034, which is gratefully acknowledged. The authors wish to thank Mr. Keith Bell for making the measurements and Mr. Jim Pantling for manufacturing and maintenance of the experimental facilities.

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Citation Excerpt :
The reliability of our measurements is indicated both by: Very good agreement between the viscosity value at the maximum Δpr in our measurements (Δpr = 0.05) and the overlapping data point of Gozalpour et al. [6]. Very good agreement between the critical viscosity estimated from our data in the two-phase region and the value estimated from the single-phase data of Canet et al. [51].
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Viscosity, density, interfacial tension and compositional data for near critical mixtures of methane + butane and methane + decane systems at 310.95 K

Abstract

Introduction

Section snippets

Apparatus

Composition measurements

Methane + butane

Conclusions

Acknowledgements

Fluid Phase Equilib.

Fluid Phase Equilib.

Fluid Phase Equilib.

J. Chem. Eng. Data

Int. J. Thermophys.

Trans. I Chem E

Ind. Eng. Chem.