| Oil-water flow in vertical and inclined pipes has been investigated theoretically and experimentally to identify and characterize the flow patterns, and to model the flow pattern transitions, holdup and pressure drop for conditions pertinent to oil-water producing wells.; A comprehensive new oil-water flow pattern classification is proposed based on data acquired in a transparent test section (2 in. ID, 51 ft long) using a mineral oil and water ({dollar}rhosb{lcub}o{rcub}{dollar}/{dollar}rhosb{lcub}w{rcub}{dollar} = 0.85, {dollar}musb{lcub}o{rcub}{dollar}/{dollar}musb{lcub}w{rcub}{dollar} = 20.0 and {dollar}sigmasb{lcub}o-w{rcub}{dollar} = 33.5 dyne/cm at 90{dollar}spcirc{dollar}F). The tests covered inclination angles of 90{dollar}spcirc{dollar}, 75{dollar}spcirc{dollar}, 60{dollar}spcirc{dollar} and 45{dollar}spcirc{dollar} from the horizontal.; The oil-water flow patterns have been grouped into two major categories based on the status of the continuous phase, including water dominated and oil dominated flow patterns. Water dominated flow patterns generally show significant slippage but relatively low frictional pressure gradients. In contrast, oil dominated flow patterns show negligible slippage but significantly large frictional pressure gradients. Six flow patterns have been characterized in vertical flow, three were water dominated and three were oil dominated. In inclined flow there were also three water dominated flow patterns, three oil dominated and a transitional flow pattern. Flow pattern maps for each of the tested inclination angles are presented.; Flow parameters, including frictional pressure drop, holdup and spatial phase distribution are functions of the oil-water flow patterns and can be effectively used in flow pattern identification. A newly designed conductance probe assisted significantly in the objective identification of the oil-water flow patterns.; Mechanistic models are proposed to predict oil-water flow pattern transitions, and to calculate water holdup and pressure drop in vertical wells. The transitions to very fine dispersed flows were evaluated by combining the turbulent kinetic energy with the surface free energy of the droplets, while the transition to churn flow was predicted based on the concept of agglomeration. A Drift Flux model was found adequate to calculate the holdup for high slippage flow patterns and a homogenous model was used for the non-slip cases. New closure relationships for the two-phase friction factor for oil dominated and water dominated flow patterns are proposed. Overall, the models compare favorably with the measured data. |
