“Measurements and modeling of phase equilibrium of oil systems containing polar chemicals”
Abstract
Chemicals are added in almost all stages of oil and gas production. It is generally accepted that efficient and cost effective oil and gas production is not possible without the use of chemicals. Monoethylene glycol (MEG) and methanol are two of the most widely used production chemicals. They are used as gas hydrate inhibitors to ensure safe production and transportation.
The prediction of mutual solubility of water, MEG/methanol and hydrocarbon fluids is important for the oil industry to ensure reliable production and processing. Phase equilibrium data are the basis of the design and of the optimization of separation processes, such as distillation, based on the distribution of compounds between the phases. As experimental data, especially those concerning phase equilibria, are the bedrock of all fundamental development of thermodynamic models and industrial processes, we shall emphazise on the means of obtaining them.
The CPA equation of state proposed by Kontogeorgis et al. [1] has been successfully applied in the past to well defined systems containing associating compounds (such as water, methanol and MEG). It has also been successfully extended to reservoir fluids in presence of water and polar chemicals, using a characterization method (Pedersen et al. [2]), with modified correlations for critical properties and acentric factor proposed by Yan et al. [3].
It is clear and well known that modeling quality is highly dependent on experimental data quality and on the knowledge or the reliable estimates of their uncertainties. In order to understand these complex systems and to further the development of CPA, more experimental data is desirable.
This work focuses on producing new experimental data for systems containing oil-water-polar chemicals. Furthermore we will model these systems using the CPA equation of state.
[1] G. M. Kontogeorgis, E. C. Voutsas, I. V. Yakoumis, D. P. Tassios, Ind. Eng. Chem. Res. 35 (1996) 4310.
[2] K. S. Pedersen, P. Thomassen, A. Fredenslund, Characterization of gas condensate mixtures, Advances in thermodynamics, Taylor & Francis, New York, 1989.
[3] W. Yan, G. M. Kontogeorgis, E. H. Stenby, Fluid Phase Equilib., 276 (2009) 75-85.