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In this study, experiments were carried out in a vertical 60-mm internal diameter pipe with air and oil (viscosities 100–330 mPa s) constituting the gas and liquid phases. Superficial air and oil velocity ranges used were 9.81–59.06 m/s and 0.024–0.165 m/s, respectively. Visual observations and change in slope of pressure drop–Vsg plot were used to identify flow pattern transition to annular flow. Using the experimental data as well as other reported data, a new correlation to predict interfacial friction factor in upward gas–viscous liquid annular flow regime was developed. Compared to the performance of 16 existing correlations using higher viscosity liquids, that of the new correlation was better. The performance of another correlation we derived for predictions at both low and higher low viscous showed good agreement with measurements. In addition, a neural network model to predict the interfacial friction factor involving both low and high viscous liquids was developed and it excellently described the experimental data.

Gas void fraction plays a significant role in determination of several multiphase flow parameters. Good insight of its behaviour coupled with accurate prediction is imperative for design of efficient equipment which has the potential to translate to higher production rates in the petroleum industry. Against the background of the prevalence of higher viscous and imminent application of highly viscous liquids in the petroleum industry, air-water and air-low viscous liquid mixtures dominate gas void fraction research in vertical pipes. In this work, gas-liquid ( μ l = 100 − 7000 m P a s ) mixtures are used to investigate the behaviour of gas void fraction in vertical pipes. The influence of superficial phase velocities and liquid viscosity are observed. Further, a combined database consisting of experimental and the reported data of Schmidt et al. (2008) is employed to evaluate the predictions of 100 existing correlations. The results indicate that the Hibiki and Ishii (2003) and Bestion (1990) correlations are the overall best and second-best performing correlations. In the absence good performing correlations for churn and annular flows, two correlations each, based on drift flux and slip ratio, are developed respectively. Predictions from these correlations show good agreement with the database and comparable performance with the overall best correlations.

It is difficult to measure the amount of associated petroleum gas (APG) generated during the production of crude oil with low gas content. To solve this problem, a new method called phase-isolation and separation (PIS) method was developed. Firstly, the phase-isolation state of the gas-liquid mixture was achieved using a swirler. The gas component was then extracted to a compact separator to perform dehydration and complete the gas-liquid separation. Finally, the completely separated gas was metered using a Venturi flowmeter. The flow patterns of low gas content multiphase flow at phase-isolation state were analyzed in laboratory. The measurement of APG using PIS was also validated by oilfield experiments. Within the experimental range, the maximum relative measurement deviation was 2.35% compared to the conventional test separator. The results show that the new APG measurement method proposed in this paper is suitable and effective for the low gas content production wells (GVF

The calculations of friction pressure drop is the most complicated in multiphase flow. Understanding of the friction pressure drop in pipes are of great importance for many industry problems. The existing friction pressure drop models are generally based on low gas and liquid velocities in horizontal and vertical pipes. In this paper, a two-phase flow experiment in inclined pipe was performed. We report the effect of superficial gas and liquid velocities on friction pressure drop, the results indicate that the pressure drop increases with the increase in superficial gas velocity and superficial liquid velocity. According to the experimental analysis and assuming that the fluid in contact with the pipe wall at high velocity is in a liquid phase, we developed a new friction pressure drop model of different flow pattern. This model based on the correlation between the fraction factor and the superficial gas and superficial liquid Reynold numbers. Compared with the previous models, the predictive performance of the present model is good and remains basically stable.