Significantly narrower annular spaces are encountered during Casing while Drilling(CwD) due to the larger diameters of the casings that are used as drill strings, comparing to those used in conventional drilling. The understanding of two phase flow in narrow annuli is important to predict gas migration in wellbores during casing/liner drilling operations, which is crucial in early kick detection and gas kick management under such circumstances.

In this study, a two-phase flow experimental apparatus using 3 ½ inch and 2 inch PVC pipes within a 4- inch outer pipe was developed to represent narrow and wide annular conduits. Liquid holdups and annular pressure losses were recorded while flowing air and water through test sections. The experimental results showed that the flow patterns within narrow annuli were more sensitive to changing air and water flow rates. New drift-flux models for narrow and wide annuli, were developed based on experimental results. These models can be further extended to a wide range of flow conditions. In addition, Computational Fluid Dynamics (CFD) models were developed using volume of fluid (VOF) method. The simulation results were in a good agreement with experimental data and new model predictions within the range of flow rates that were used in this study.

You can access this article if you purchase or spend a download.