(352f) Modeling of Droplet Coalescence and Breakage in Oil-Water Pipeline Using One-Group Interfacial Area Transport

Authors: 
Tsai, K., Shell International E&P
Water fallout in oil transport pipelines has significant impact on corrosion inhibition management for the oil and gas industry. To apply the corrosion inhibitors where and when it is needed is a delicate balance between how water and oil phases interact and the inhibitorâ??s dissolution in each phase. As a precursor, it is extremely important to understand the evolution of water dispersion in oil during various phases of the production cycle.

In this study water is considered as the dispersed phase and its transport described by the one-group interfacial area transport model. The droplet size follows the evolution of interfacial area concentration by considering the impact of turbulent shearing and droplet collision. The one-group model by Wu et al. (1997) is adopted as the baseline and modifications are applied to their coalescence and breakage formulations following the work of Abid and Chesters (1994).

The original model of Wu et al. (1997) was proposed for bubbly flows, and while their geometrical arguments for droplet collision and breakage probability remain valid; their efficiency formulations can be significantly different. The mechanisms of coalescence drainage and breakage efficiency were found to be highly dependent on droplet size, surface tension, viscosity, flow regime and volume fraction (Abid and Chesters, 1994). The modified formulation was applied to model the bench-scale (2.5� pipe) experiment of Simmons and Azzopardi (2001) and scaled up to predict the full scale (16� pipe) measurements of Fairuzov et al. (2000). The results were found to match very well with the full-scale data up to 20% water volume fraction. The model was implemented using commercial computational fluid dynamics software through user accessible subroutines.

References

Abid, S and A. K. Chesters, â??The drainage and rupture of partially-mobile files between colliding drops at constant approaching velocity,â? Int. J. Multiphase Flow, 20, pp. 613-629, 1994.

Fairuzov, Y. V., P. Arenas-Medina, J. Verdejo-Fierro and R. Gonzales-islas, â??Flow pattern transitions in horizontal pipelines carrying oil-water mixtures: full scale experiments,â? J. Energ. Res. Tech., pp. 169-176, 2000.

Simmons, M. J. H., B. J. Azzopardi, â??Drop size distributions in dispersed liquid-liquid pipe flow,â? Int. J. Multiphase Flow, 27, pp. 843-859, 2001.

Wu, Q, S. Kim and M. Ishii, â??One-group interfacial area transport in vertical bubbly flow,â? Int. J. Heat Mass Transfer, 41, pp. 1103-1112, 1997.