Experimental study of two and three phase flows in large diameter inclined pipes

Steady-state and transient experiments of water–gas, oil–water and oil–water–gas multiphase flows were conducted on a transparent 11 m long, 15 cm diameter, inclinable pipe using kerosene, tap water and nitrogen. The pipe inclination was varied from 0° (vertical) to 92° and the flow rates of each phase were varied over wide ranges. Fast-acting valves enabled the trapping of the fluid flowing in the pipe, which in turn allowed for the accurate measurement of the absolute volumetric fraction (holdup) of each phase. A nuclear densitometer, as well as ten electrical probes at various locations along the pipe, provided additional steady-state and transient measurements of the holdup. A total of 444 tests were conducted, including a number of repeated tests. Bubble, churn, elongated-bubble, slug, and stratified/stratified-wavy flows were observed for water–gas and oil–water–gas flows, while dispersed/homogeneous, mixed/semi-mixed and segregated/semi-segregated flows were observed for oil–water flows. Extensive results for holdup as a function of flow rates, flow pattern and pipe inclination are reported, and the various techniques for measuring holdup are compared and discussed. The flow pattern and shut-in holdup are also compared with the predictions of a mechanistic model. Results show close agreement between observed and predicted flow pattern, and a reasonable level of agreement in holdup.