Analysis and comparison of three comprehensive mechanistic hydrodynamic methods for vertical upward and deviated gas-liquid flow through pipes

When oil or gas are extracted from an underground reservoir they usually flow in the well tubing or casing simultaneously as immiscible oil and gas. The difference in velocities between the phases is known as slip and creates a liquid inventory in the well. Predicting the exact pressure loss and the content and distribution of the liquid and gas in the form of flow patterns is a complex and still unsolved problem.;This research project provides a thorough literature search, followed by an explanation of concepts and analysis of the types of first principles used by all models, and finally with comparative simulations showing the performance of isolated components and of the models as a whole. The qualitative determination of trends in pressure gradient and liquid accumulation or hold-up was studied through sensitivity analysis of the pipe diameter, of the angle of inclination, and of the fluid properties. The parametric analysis and the kind of graphic output of pressure gradients and hold-up used to compare two different models had not been applied to this problem before. The quantitative assessments of the results were made with data from the literature that used laboratory flow loop experiments and field experimental data in deep wells, high water-cut gas wells, gas condensate wells, deviated wells, gas-lifted wells, and oil wells.;Engineers rarely find direct use for the newest published science on this topic unless they can use it as a component of an engineering simulation program capable of doing the thousands of small tedious calculations involved in predicting the pressure drop and heat transfer in a production well. Therefore the comparisons for production well cases had to be made by writing special modules that could be used by the commercial simulation program WELLFLO (c).;The final comparisons of three well data sets taken from the literature show that the current scientific knowledge is comparable in accuracy with the best of the empirical correlations and very close to proprietary technology, which are both used extensively by industry. The advantages of mechanistic models, though, is their dependency on fluid properties and geometry that makes them more reliable when used across a wide range of values of these parameters.;Traditionally, industry has used empirical correlations based on large data sets. In the last three decades more descriptive and first-principle based methods have evolved but have been embraced slowly in spite of their promise for general application. This research highlights the common threads in these advances and shows the trend toward better use of basic physical laws. This work shows that their accuracy when implemented in a production well simulator for solving cases provided in the literature is comparable to accepted industry standards.