Experimental studies on pipeline transportation of high internal phase emulsions using water-lubricated core-annular flow method

High internal phase emulsions (HIPEs) are highly viscous complex fluids and cannot be easily transported through pipelines. In the present work, we report experimental studies on transportation of HIPEs using water-lubricated core-annular flow (CAF) in a horizontal pipe. We explore two sets of w/o HIPEs having different mass fractions of continuous phase (6.5 and 15 wt%, respectively). The rheology of HIPEs is carefully characterized, and both sets of emulsions are found to be shear thinning, having significant yield stress. Using a flow loop, we observe stable CAF regimes for a range of HIPE and water flow rates. Pressure drop in the CAF regime is found to be relatively independent of water flow rate and increases almost linearly with emulsion flow rate. We propose a simplified theory for CAF of non-Newtonian yield-stress fluids, which explains radial compression of core-fluid near the injector, and reduction of holdup with increasing core-to-annulus flow rates.