Slug flow phenomena in inclined pipes

Most of the methods for predicting pressure drop in gas-liquid two phase flow in wellbores have been developed for vertical flow conditions. Application of these methods to predict the flow behavior in non vertical deviated wells is inadequate, and can result in substantial errors. This is due to the changes in the physical flow phenomena taking place in inclined pipes. In particular, the Taylor bubble rise velocity (drift velocity) changes significantly with the inclination angle, affecting the liquid holdup and pressure drop in the system.; This study focuses on the effect of the inclination angle on the Taylor bubble rise velocity. An experimental test facility has been designed and constructed, capable of rotating from horizontal to vertical. An extensive experimental program has been carried out on a 15 m (50 ft) long, 0.051 m (2 in) diameter test section, utilizing a new computer based data acquisition system. Detailed information of the flow phenomena has been obtained. Measurements of the Taylor bubble rise velocity under flowing and stagnant liquid column conditions, and the corresponding pressure and liquid holdup distributions have been acquired for all inclination angles between vertical (90{dollar}spcirc{dollar}) and horizontal (0{dollar}spcirc{dollar}).; A new mechanistic model has been developed for the prediction of the Taylor bubble drift velocity. The model is an extension of the Benjamin analysis for the horizontal case to the inclined and vertical cases, taking into account surface tension effects. The proposed model is applicable for the entire range of inclinations, from horizontal to vertical. Good agreement is observed between the experimental data and the proposed model.