Представлены результаты сравнительного анализа показателей ключевых факторов механизма увеличения нефтеотдачи пластов с использованием газов в сверхкритическом флюидном состоянии, применительно к диоксиду углерода и пропану (пропан/бутановым смесям). Вышеотмеченные факторы, как предмет рассмотрения, включают: растворяющую способность сжатых газов по отношению к нефти и ее компонентам; фазовое поведение бинарных систем, включающих обозначенные вытесняющие агенты и углеводороды нефти; критические параметры бинарных систем I–II типов фазового поведения; сжимаемость диоксида углерода и пропана в условиях осуществления процесса вытеснения нефти в рамках третичной нефтедобычи; вязкость сред, участвующих в обсуждаемом процессе и наконец, набухание нефти в результате ее насыщения газом. Приведены результаты экспериментальной реализации процесса экстракционного извлечения нефти, реализованного в сверхкритических флюидных условиях с использованием в качестве экстрагента диоксида углерода в одном случае и пропана в другом. Установлено, что пропан и пропан/бутановые смеси в сопоставлении с СО 2 имеют трех и более кратное превосходство в растворяющей способности по отношению к компонентам нефти в условиях процесса вытеснения; чаще формируют с компонентами нефти предпочтительные для процесса ее извлечения системы с I–II типом фазового поведения; мощность компрессора, затрачиваемая на сжатие диоксида углерода и метана, почти в три и более раза, соответственно, превосходит ту, что необходима при сжатии пропана и, наконец, пропан в условиях вытеснения нефти обладает существенно меньшей вязкостью, что в совокупности указывает на предпочтительность пропана и пропан/бутановых смесей в процессе вытеснения нефти в рамках процесса третичной нефтедобычи.

The results of comparative analysis for the key factors of the mechanism of oil-recovery enhancement with the use of gases in a supercritical fluid state as applied to carbon dioxide and propane (propane/butane mixtures) are presented. The above-mentioned factors as a subject of consideration incorporate the dissolving ability of compressed gases with respect to oil and its components, the phase behavior of binary systems containing the mentioned displacing agents and oil hydrocarbons, the critical parameters for the binary systems of fluid-phase behavior types I–II, the compressibility of carbon dioxide and propane under oil-displacement process conditions in tertiary oil production, the viscosity of the media participating in the discussed process and, finally, the swelling of oil as a result of its saturation with a gas. The results of experimental implementation under supercritical fluid conditions are given for an extraction oil-recovery process with carbon dioxide as an extragent in one case and propane in the other case. It is established that propane and propane/butane mixtures are three or more times superior to CO 2 in dissolving ability with respect to oil components under displacement-process conditions; that they more often form systems of fluid-phase behavior types I–II with the oil components, which is preferable for the process of its recovery; that the compressor power spent on the compression of carbon dioxide and methane is threefold or more higher than for propane; and, finally, that propane has a much lower viscosity under oil-displacement conditions. In sum, propane and propane/butane mixtures are preferable for use in the oil-displacement process within the framework of tertiary oil production.

Objectives. The aim of this work is to modernise a VT-KHTI densimeter operated by the method of hydrostatic weighing in order to study the density of highly viscous oils and oil products in the temperature range from 293 K to 473 K at atmospheric pressure.Method. Among the many methods for studying density, the following were used in the course of the study: the constant- and variable-volume piezometer method and the method of hydrostatic weighing.Results. The results of the densimetric study of highly viscous oils obtained from the Republic of Tatarstan in the temperature range from 293 K to 473 K at atmospheric pressure. The following grades are presented: Ashalchinskaya oil (super-viscous, SVO); Kuakbash oil (sulphur), Kichuy oil and Devon oil. Following an analysis and selection of methods for measuring density, a technique for error estimation and densimeter calibration is presented. A calculated expression for the hydrostatic weighing method, derived from the modernised hydrostatic densimeter design for measuring the density of highly viscous oils, is presented.Conclusion. The VT-KHTI densimeter for vacuum working fluids has been modernised and calibrated for research work on measuring the dynamic viscosity coefficient of both Newtonian and non-Newtonian liquids.

Current paper represents the results of viscosity and density measurements of vacuum oils for diffusion vacuum pumps. Vacuum oil samples are represented by the following brands: VM-1S, LEYBONOL LVO 500 and Alcarin-D24. All the measurements have been carried out at atmospheric pressure: viscosity has been measured by the capillary method in the temperature range from 293 K to 373 K, and density has been measured by the pycnometer and hydrostatic weighing methods in the temperature range from 293 K to 473 K.

The density and viscosity of liquid 1-hexene and 1-heptene have been simultaneously measured over the temperature range from (298 to 473) K and pressures up to 245 MPa using the hydrostatic weighing and falling-body techniques, respectively. The combined expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95 % confidence level with a coverage factor of k = 2 is estimated to be 0.15 % to 0.30 %, 0.05 %, 0.02 K, and 1.5 % to 2.0 % (depending on temperature and pressure ranges), respectively. The measured densities were used to develop a Tait-type equation of state for liquid 1-hexene and 1-heptene. Theoretically based Arrhenius-Andrade and Vogel-Tamman-Fulcher (VTF) type equations with pressure-dependent coefficients were used to represent the temperature and pressure dependences of the measured viscosities for liquid 1-hexene and 1-heptene. Also the friction theory (FT) viscosity model together with derived Tait-type equation of state (EOS) was used to accurately represent measured viscosity data. The measured values of the density and viscosity of 1-hexene and 1-heptene in the liquid phase were compared in detail with reported data and with the values calculated from correlations.

The density and viscosity of \(n\)-heptane have been simultaneously measured over the temperature range from 298 K to 470 K and at pressures up to 245 MPa using the hydrostatic weighing and falling-body techniques, respectively. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95 % confidence level with a coverage factor of \(k= 2\) is estimated to be 0.15 % to 0.30 %, 0.05 %, 0.02 K, and 1.5 % to 2.0 % (depending on temperature and pressure ranges), respectively. The measured densities were used to develop a Tait-type equation of state for liquid \(n\)-heptane. Theoretically based Arrhenius–Andrade and Vogel–Tamman–Fulcher type equations with pressure-dependent coefficients were used to describe the temperature and pressure dependences of the measured viscosities for liquid \(n\)-heptane. The measured values of the density and viscosity were compared in detail with reported data and with the values calculated from a reference EOS and correlation models for the viscosity.

Density and viscosity of monoethylene glycol (MEG), diethylene glycol (DEG), and triethylene glycol (TEG) and their binary, (50%MEG + 50%DEG), (50%MEG + 50%TEG), (50%DEG + 50%TEG), and ternary (33.33%MEG + 33.33%DEG + 33.34%TEG) mixtures have been simultaneously measured over the temperature range from 293 K to 465 K and at pressures up to 245 MPa using the hydrostatic weighing and falling-body techniques. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be 0.15-0.30%, 0.05%, 0.02 K, and 1.5-2.0% (depending on temperature and pressure ranges), respectively. Tait-type equation of state (EOS) for pure MEG, DEG, and TEG has been developed using the measured (p, rho, T) data. Theoretically based Arrhenius-Andrade and Vogel-Tamman-Fulcher type equation with pressure dependent coefficients was used to describe the temperature dependence of measured viscosities for pure polyethylene glycols. (C) 2011 Elsevier B.V. All rights reserved.

A new apparatus to measure simultaneously the density and viscosity of liquids has been designed and constructed based on the hydrostatic weighing and falling-body principles. The density and viscosity of monoethylene glycol (MEG), diethylene glycol (DEG), and triethylene glycol (TEG) and their binary, (50%MEG + 50%DEG), (50%MEG + 50%TEG), (50%DEG + 50%TEG), and ternary (33.33%MEG + 33.33%-DEG + 33.34%TEG) mixtures have been measured over the temperature range from 293 K to 473 K and at atmospheric pressure. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be 0.15% to 0.30%, 0.05%, 0.06 K, and 1.5% to 2.0% (depending on temperature and pressure ranges), respectively. The theoretically based Arrhenius-Andrade and Vogel-Tamman-Fulcher type equations were used to describe the temperature dependence of measured viscosities for pure polyethylene glycols and their mixtures. (C) 2011 Elsevier Ltd. All rights reserved.

Evaluation of characteristic points in the neighborhood of the critical point and far from it on binodal and critical isobar of water in liquid state is put forward. Coefficients for binodal and critical isobar equations and characteristic points are presented.