A simplified model for oil-water flow in vertical and deviated wellbores

© Copyright 1998, Society of Petroleum Engineers, Inc. This paper presents the results of an experimental study and a semitheoretical analysis of two-phase oil-water flow in vertical and deviated systems. The study focuses on water-dominated flow regimes, where the patterns may be termed as bubbly flow, pseudoslug flow, and churn flow. A drift-flux approach is taken to analyze the flow behavior of oil-water systems. For the three flow regimes investigated, the drift flux of the lighter oil phase is found to be dependent on its in-situ volume-fraction in addition to the terminal bubble-rise velocity. This behavior is in contrast to the gas-liquid flow, where the drift flux has often been found to equal to the bubble-rise velocity. For flow in both vertical and deviated pipes, we were able to develop a single expression for the drift flux, uow, resulting in a single equation for the in-situ oil fraction, fO, for the three flow regimes studied. We correlated fO with the oil superficial velocity, vos, and the terminal rise velocity, v∞θ, using the expression, fO = vos/{1.2vm + v∞θ(1-fo)2}. In a deviated pipe, the terminal rise velocity, vinfin;θ, is correlated with that in a vertical pipe by vinfin;θ = vinfin; (cos θ)0.5 (1 + sin θ)2. The performance of the proposed method in estimating f0 is in good agreement with our measurements. Published data further augment the approach presented here.

A simplified model for oil-water flow in vertical and deviated wellbores Conference Paper