A Study of Oil/Water Flow Patterns in Horizontal Pipes

Abstract

Summary Oil/water flow-pattern transitions in horizontal pipes have been studied botd experimentally and tdeoretically. A new state-of-tde-art oil/water test facility was designed, constructed, and operated. A transparent test section (5.013-cm inside diameter × 15.54 m long) can be inclined at any angle, to study botd upward and downward flow simultaneously. Mineral oil and water were tde working fluids (µo/µw= 29.6, ρolρw= 0.85, and σ = 36 dynes/cm at 25.6°C). A new classification for oil/water flow patterns based on published and acquired data is proposed. Six flow patterns were identified and classified into two categories: segregated flow and dispersed flow. Stratified flow and stratified flow witd some mixing at tde interface (ST&MI) are segregated flow patterns. tde dispersed flow can be eitder water dominated or oil dominated. A dispersion of oil in water over a water layer and an emulsion of oil in water are water-dominated flow patterns. An emulsion of water in oil and a dual dispersion are oil-dominant flow patterns. The oil/water flow-pattern transitions for light oils are predicted using tde two-fluid model and a balance between gravity and turbulent fluctuations normal to tde axial flow direction. Stability analyses reveal tdat tde stratified/nonstratified transition must be addressed witd tde complete two-fluid model. Stratified flow is predicted by tde viscous Kelvin-Helmholtz (KH) analysis while in-viscid KH tdeory predicted tde ST&MI flow pattern. For tde dispersed flow pattern, tde predicted drop sizes from tde Hinze and Levich models are modified to account for tde effect of tde dispersed phase concentration. tde controlling parameter for tde coalescence phenomena is tde water fraction. tde model performance is excellent and compares well witd published data.