No abstract

A previous viscosity‐temperature correlation (Puttagunta et al., 1992) is extended to include a pressure term and employed successfully in predicting the combined effect of temperature and pressure on the viscosity of Canadian bitumens and heavy oils. Predictions are made on new sets of data based on a single measurement of viscosity at 30°C and 101.3 kPa pressure; and the results show similar accuracy as obtained in the sets of data used in developing the correlation. The correlation yields an absolute average deviation between predicted and experimental viscosity of 4.79% and a correlation coefficient of 0.99 over a range of temperatures between 20 and 120°C and gauge pressures between 0 and 18 MPa.

A stochastic modeling of the formation of cavitation bubbles on a specific example is proposed. In this case, the initial stage of hydrodynamic cavitation in the flow part of the axial valve, the separator, was studied. A distinctive feature of this regulating device is the external location of the locking organ. An expression for the differential distribution function of the number of bubbles according to the degree of valve opening is obtained. The model takes into account the design and operating parameters of the axial valve, as well as the physical and mechanical properties of the working environment.

No abstract

In the recovery of bitumen, viscosity reduction becomes important, both below and above the ground. The addition of a liquid diluent is thought to break down or weaken the intermolecular forces which create high viscosity in bitumen (1) . The effect is so dramatic that the addition of even 5% diluent can cause a viscosity reduction in excess of 80%; thus, facilitating the in situ recovery and pipe line transportation of bitumen.The knowledge of the bitumen-diluent viscosity is highly important, since without it, calculations in upgrading process, in situ recovery, well simulation, heat transfer, fluid flow, and a variety of other engineering problems would be difficult or impossible to solve. This paper presents the development of a simple correlation to predict the viscosity of binary mixtures of bitumen-diluent in any proportion. AbstractThe viscosity model is an important component in enhanced oil recovery packages and, for pure bitumen, several accurate models are available. In this study, a simple correlation presented in an earlier publication is extended to predict the viscosity of bitumen-diluent mixtures, as well as the mass fraction required to reduce bitumen viscosity to pumping viscosity.In developing the viscosity model, viscosities of pure bitumen and diluent were used as the endpoints, and the diluent mass fraction was raised to a power of "n" (a viscosity reduction parameter) to account for the sharp drop in bitumen viscosity with increase in diluent mass fraction. The model was developed with 99 data points from three different bitumens and five diluents; spanning a viscosity range of 10 -1 to 10 6 mm 2 /s. The model was used to recalculate the viscosity and mass fraction values, and results compared with similar correlations by Cragoe and Chirinos. The best match was obtained with our correlation, with overall average absolute deviations of 12% and 5% for viscosity and mass fraction predictions, respectively. Predictions on data not used in developing the model showed an excellent match between experimental and predicted values, with an overall average absolute deviation of below 10% for viscosities of mixtures at 25˚ C, 60.3˚ C, and 82.6˚ C.

No abstract

A generalized viscosity correlation and its application are presented in this paper for heavy oils, bitumens and light oils from Saskatchewan. The correlation is shown to predict accurately the viscosity at any desired temperature and pressure, and also at any concentration of dissolved gases. Interestingly, the correlation predicted with the same accuracy in both kinematic and absolute viscosities. By adjusting the parameters of the shape factor, the correlation is shown also to predict accurately the viscosity of various Chinese waxy crude oils, containing up to 40% water, at different temperatures. The average absolute deviations obtained with the correlation are: 4.8% Saskatchewan light oils in kinematic viscosity, 4.6% and 2.2% for the viscosity of Chinese crude oils. The input parameter required for this correlation is just one viscosity measurement of the dead oil made at atmospheric pressure and at a convenient temperature such as 30 ºC where the composition of the oil sample is unaltered during the measurement. Introduction Numerous efforts have been directed towards the development of correlations capable of predicting adequately crude oil viscosity as a function of temperature, pressure, and/or composition(1–7). This is principally because viscosity values of crude oils and crude oils containing dissolved natural gases are required in various petroleum engineering calculations. Several empirical and semi-empirical viscosity-temperature correlations have been summarized by Reid et al.(8) The most convenient viscosity correlations in use are those based on one-parameter equation since they involve fewer numerical computations. Some of the one-parameter correlations, however, are only suitable for the specific oil type for which they were developed. New parameters and constants have to be developed for any slight changes in the physical oil properties such as density, API gravity, molecular weight, etc., thus involving extra numerical computations. Others require several experimental viscosityalues at varying conditions of temperature, pressure or composition to make predictions. The correlation we present here is a generalized one-parameter viscosity equation already published by Puttagunta et al.(9) The applicability and accuracy of the correlation have been demonstrated in several other publications(10–13). Therefore, the focus of this paper is not to present a new viscosity correlation but to evaluate the correlation on new experimental data recently obtained for a variety of Saskatchewan crudes. The Puttagunta et al. viscosity correlation is as follows: Equation (1) Available In Full Paper. where S is a parameter which depends on b, C is a constant, T is temperature in °C, P is gauge pressure (MPa), X is dissolved gas concentration, (mole %), and μ is viscosity in Pas. b is the viscosity characterization parameter obtained from one viscosity measurement at 30 °C and one atmosphere as follows: Equation (2) Available In Full Paper. In the correlation, ∑Cti represents the sum of the concentration terms for all i gases dissolved in the heavy oil or bitumen, and thus Ct is given as: Equation (3) Available In Full Paper.

No abstract