Most of the existing drift velocity models have limitations, and sometimes low predictive capabilities, primarily because they are derived from experimental data which scarcely account for the combined effect of viscosity, surface tension and pipe inclination. Published data of drift velocity of elongated bubbles in pipes have been extracted from the open literature, and new data have been generated from Taylor bubble experiments conducted in a low pressure flow loop using nominal oil viscosities of 160cP and 1140cP in 0.099m and 0.057m internal diameter inclined pipes (1.0 to 7.5 degrees from horizontal). These data have been processed and a simplified generalised drift velocity correlation established. The evaluation of some existing elongated bubble rise velocity has also been carried out. The prediction of the drift velocity of a single elongated gas bubble in liquid in pipes can sometimes be overestimated by 20% or more, and sometimes be underestimated by 20% or more. It is shown that the new proposed simplified generalised correlation has an improved predictive capability when used to estimate the drift velocity of a bubble in stagnant liquid in a pipe.

One of the fundamental questions that must be addressed in the effective design and operation of pipeline lubrication of heavy oil is; ''how much time will be needed to restart a blocked core annular flow (CAF) line after shutdown due to fouling or pump failures'', if the pipe is to be cleaned using water only. In this work, laboratory results of shutdown and restart experiments of high-viscous oil conducted in a 5.5-m-long PVC horizontal pipe with internal diameter of 26 mm are first presented. A new correlation for the prediction of the restart time of a shutdown core annular flow line is then formulated. The predictive capabilities of the correlation are checked against measured restart time and pressure drop evolution data. Somewhat high but still reasonable predictions are obtained. The restart time correlation, together with the associated correlations formulated as well, can be of practical importance during the engineering design of highviscous oil pipeline transportation facility for predicting restart process.

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For energy calculation and hydrocarbon dewpoint calculation of pipeline gas, many gas processors and end-users are now applying equation of state, either a Peng-Robinson (PR) or Soave-Redlich-Kwong (SRK) equation of state, to the pipeline gas composition after splitting the C6+ component into a fixed ratio of n-hexane, n-heptane and n-octane: varying predictions are obtained because the commonly used percentage C6+ composition splits published in GPA standard are based on empirical studies of most pipeline gases. In addition, several different software packages are available to the industry to perform dew point calculations, and each of these may yield different predictions using the same gas compositions and equations of state. This work therefore presents the ranking of the common C6+ split schemes for hydrocarbon dewpoint determination on the basis of C6+ mole fraction through the study of several common C6+ composition splits of pipeline gas applied to a large set of field and hypothetical C6+ data by means of HYSYS(with PR EOS and SRK EOS for predicting hydrocarbon dewpoint.